Articoli di riviste: "Limit of Detection (LOD)"

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Loftus, Michele L., Leila M. Barraj e J. Robert Tomerliv. "Effect of the Limit of Detection on Exposure Assessment". Journal of AOAC INTERNATIONAL 75, n. 5 (1 settembre 1992): 911–15. http://dx.doi.org/10.1093/jaoac/75.5.911.

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Abstract An important component in evaluating the risk from pesticides in our foods is estimating the dietary exposure from the pesticide. This paper examines the effect of the limit of detection (LOD) on dietary exposure assessment. When designing food surveys for the purpose of estimating exposure from residues in foods as eaten, the effect of the LOD on exposure assessment should be evaluated before commencement of the analytical phase of the food survey. The purpose of the evaluation is to determine the LOD required to adequately quantify human exposure. The evaluation entails either determining the level at which the LOD is low enough to obtain exposure estimates that fall in the acceptable range or the level at which further reduction of the LOD will not result in additional observable reduction in estimates of exposure. Models describing exposure as the product of consumption and the magnitude of the residue in food are presented. Residue data from controlled field studies are used as examples to determine the optimum LOD to use in a food survey for assessment of exposure from a chronic adverse health effect. A computer program, EXPOSURE 1®, based on the U.S. Department of Agriculture Nationwide Food Consumption Survey, is used to estimate dietary exposure.

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Norrod, Karen L., Leo M. Sudnik, David Rousell e Kathy L. Rowlen. "Quantitative Comparison of Five SERS Substrates: Sensitivity and Limit of Detection". Applied Spectroscopy 51, n. 7 (luglio 1997): 994–1001. http://dx.doi.org/10.1366/0003702971941377.

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Five surface-enhanced Raman scattering (SERS) substrates were quantitatively compared for ease of preparation, sensitivity, limit of detection (LOD), reproducibility, and stability. Specifically, vapor-deposited Ag films, electrochemically roughened Ag electrodes, nitric acid-etched Ag foil, Tollens-produced Ag films, and photore-duced Ag films on TiO2 were examined. Of these substrates, post-deposition-annealed Ag films exhibited the greatest sensitivity and lowest LOD, with 152 ± 1 counts per femtomole and an LOD of 0.36 ± 0.02 femtomoles of trans-1,2-bis(4-pyridyl)ethene (BPE). The substrate demonstrating the poorest sensitivity and highest LOD was Ag deposited from the Tollens reaction, with 0.38 ± 0.01 counts per femtomole and an LOD of 270 ± 20 femtomoles of BPE. The easiest substrate to prepare, nitric acid-etched Ag foils, exhibited a sensitivity of 0.485 ± 0.008 counts per femtomole and an LOD of 200 ± 10 femtomoles of BPE.

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Linnet, Kristian, e Marina Kondratovich. "Partly Nonparametric Approach for Determining the Limit of Detection". Clinical Chemistry 50, n. 4 (1 aprile 2004): 732–40. http://dx.doi.org/10.1373/clinchem.2003.029983.

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Abstract Background: According to recent International Organization for Standardization (ISO) standards, the limit of detection (LoD) of an assay should be estimated taking both type I (α) and II (β) errors into account. The suggested procedure, however, supposes gaussian distributions of both blank and sample measurements and a linear calibration curve. In clinical chemistry, asymmetric, nongaussian blank distributions are common, and the calibration curve may be nonlinear. We present a partly nonparametric procedure that takes these aspects into account. Methods: Using theoretical distribution models and simulation studies, we developed a LoD estimation procedure suitable for the field of clinical chemistry that is partly based on nonparametric statistics. Results: For sample size n, the nonparametrically determined 95th percentile of the blank measurements {obtained as the value of the [n(95/100) + 0.5]th ordered observation} defines the limit for results significantly exceeding zero [limit of blank (LoB)]. The LoD is the lowest value that is likely to yield a result exceeding the LoB. LoD is estimated as: LoB + cβ × SDS, where SDS is the analytical SD of a sample with a low concentration; cβ = z1 − β/[1 − 1/(4 × f)]; z1 − β is the standard normal deviate; and f is the number of degrees of freedom for estimation of SDS. cβ is approximately equal to 1.65 for a type II error of 5%. Approaches and needed tabular values for calculation of confidence limits are presented as well as sample size. Worked examples are given to illustrate estimation and verification of the limit of detection. Simulation results are used to document performance. Conclusion: The proposed procedure appears useful for application in the field of clinical chemistry and promotes a standardized approach for estimating LoDs of clinical chemistry assays.

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Oleneva, Ekaterina, Maria Khaydukova, Julia Ashina, Irina Yaroshenko, Igor Jahatspanian, Andrey Legin e Dmitry Kirsanov. "A Simple Procedure to Assess Limit of Detection for Multisensor Systems". Sensors 19, n. 6 (18 marzo 2019): 1359. http://dx.doi.org/10.3390/s19061359.

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Currently, there are no established procedures for limit of detection (LOD) evaluation in multisensor system studies, which complicates their correct comparison with other analytical techniques and hinders further development of the method. In this study we propose a simple and visually comprehensible approach for LOD estimation in multisensor analysis. The suggested approach is based on the assessment of evolution of mean relative error values in calibration series with growing analyte concentration. The LOD value is estimated as the concentration starting from which MRE values become stable from sample to sample. This intuitive procedure was successfully tested with a variety of real data from potentiometric multisensor systems.

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Liu, Yang, Xin Li, Jie Cheng, Na Zhou, Lingqian Zhang, Haiyang Mao e Chengjun Huang. "SERS devices with “hedgehog-like” nanosphere arrays for detection of trace pesticides". Journal of Innovative Optical Health Sciences 14, n. 04 (23 giugno 2021): 2141005. http://dx.doi.org/10.1142/s1793545821410054.

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The development of surface-enhanced Raman scattering (SERS) devices for detection of trace pesticides has attracted more and more attention. In this work, a large-area self-assembly approach assisted with reactive ion etching (RIE) is proposed for preparing SERS devices consisting of Ag-covered “hedgehog-like” nanosphere arrays (Ag/HLNAs). Such a SERS device has an enhancement factor of [Formula: see text], a limit of detection (LOD) up to 10[Formula: see text][Formula: see text]M for Rhodamine 6G (R6G) analytes, and a relative standard deviation (RSD) smaller than 10%, demonstrating high uniformity. Besides, for pesticide detections, the device achieves an LOD of 10[Formula: see text][Formula: see text]M for thiram molecules. It indicates that the proposed SERS device has a promising opportunity in detecting toxic organic pesticides.

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Armbruster, D. A., M. D. Tillman e L. M. Hubbs. "Limit of detection (LQD)/limit of quantitation (LOQ): comparison of the empirical and the statistical methods exemplified with GC-MS assays of abused drugs". Clinical Chemistry 40, n. 7 (1 luglio 1994): 1233–38. http://dx.doi.org/10.1093/clinchem/40.7.1233.

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Abstract The limit of detection (LOD) for any analytical procedure, the point at which analysis is just feasible, may be determined by a statistical approach based on measuring replicate blank (negative) samples or by an empirical approach, consisting of measuring progressively more dilute concentrations of analyte. The limit of quantitation (LOQ), or concentration at which quantitative results can be reported with a high degree of confidence, may likewise be determined by either approach. We used both methods to determine LOD and LOQ for forensic gas chromatographic-mass spectrometric (GC-MS) analyses of abused drugs. The statistically determined LOD and LOQ values for these assays underestimated the LOD because of the large imprecision associated with blank measurements and the inability of blank samples to meet typical GC-MS acceptance criteria. The empirical method provided much more realistic LOD values, supported by reasonable experimental data, and are 0.5-0.03 the magnitude of the corresponding statistical LODs. The empirical LODs and LOQs are identical for these GC-MS assays. The observations made here about the LOD/LOQ for specific forensic GC-MS procedures are generally applicable to any type of analysis.

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Saraf, Nileshi, Alexander Bosak, Alicia Willenberg, Soumen Das, Bradley Jay Willenberg e Sudipta Seal. "Colorimetric detection of epinephrine using an optimized paper-based aptasensor". RSC Adv. 7, n. 77 (2017): 49133–43. http://dx.doi.org/10.1039/c7ra10272k.

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Parikh, Ravi H., Stephen L. Seliger, James de Lemos, Vijay Nambi, Robert Christenson, Colby Ayers, Wensheng Sun et al. "Prognostic Significance of High-Sensitivity Cardiac Troponin T Concentrations between the Limit of Blank and Limit of Detection in Community-Dwelling Adults: A Metaanalysis". Clinical Chemistry 61, n. 12 (1 dicembre 2015): 1524–31. http://dx.doi.org/10.1373/clinchem.2015.244160.

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Abstract BACKGROUND There is controversy regarding whether to report concentrations of high-sensitivity cardiac troponin T (hs-cTnT) to the limit of blank (LOB) (3 ng/L) or the limit of detection (LOD) (5 ng/L) of the assay in community-based cohorts. We hypothesized that hs-cTnT concentrations between the LOB and LOD would be associated with poorer cardiovascular outcomes compared to concentrations below the LOB. METHODS hs-cTnT was analyzed in a total of 10 723 participants from the Cardiovascular Health Study (CHS), Atherosclerosis Risk in Communities (ARIC) study, and Dallas Heart Study (DHS). Participants were divided into 2 groups, those with hs-cTnT concentrations below the limit of blank (LOB) (<3 ng/L) and those with hs-cTnT between the LOB and limit of detection (LOD) (3–4.99 ng/L). Cross-sectional associations with traditional cardiovascular risk factors and cardiac structural measurements, and longitudinal associations with long-term cardiovascular outcomes of incident heart failure and cardiovascular death, were determined. RESULTS Participants with hs-cTnT between the LOB and LOD for all 3 cohorts were older, more likely to be male, and have a higher burden of cardiovascular risk factors and structural pathology. A metaanalysis of the 3 cohorts showed participants with hs-cTnT between the LOB and LOD were at increased risk of new-onset heart failure (hazard ratio, 1.18; 95% CI, 1.02–1.38) and cardiovascular mortality (hazard ratio, 1.29; 95% CI, 1.06–1.57). CONCLUSIONS hs-cTnT concentrations between the LOB and LOD (3–4.99 ng/L) are associated with a higher prevalence of traditional risk factors, more cardiac pathology, and worse outcomes than concentrations below the LOB (<3 ng/L).

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Syahrir, Muhammad, Nurul Hidayat Aprilita e Nuryono Nuryono. "VALIDASI METODE ANALISIS POLISIKLIK AROMATIK HIDROKARBON (PAH) DALAM SEDIMEN DI SEKITAR PANTAI MAKASSAR". Jurnal Kimia Terapan Indonesia 17, n. 1 (10 giugno 2015): 9–14. http://dx.doi.org/10.14203/jkti.v17i1.18.

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Validation of analysis method of PAH have been done in marine sediment of Macassar Coast by Gas Chromatography (GC-FID). Validation of method include: limit of detection (LoD), limit of quantification (LoQ) and linearity range. The results of validation method of 7 types PAHs (Naphtalene, Acenaphtene, Penanthrene, Fluoranthene, Pyrene, Benzo (a) Anthracene and perylene) give a linearity range between 0.5 to 20 ppm with an average linearity approaches a value of 1. LoD for Naphtalene; Acenaphthene; Penanthrene; Fluoranthene; Pyrene; Benzo (a) Anthracene; and Perylene are 3.541; 0.208; 1,736; 1.737; 1,738; 12.124; and 2,128 ppm, respectively. LoQ for Naphtalene; Acenaphthene; Penanthrene; Fluoranthene; Pyrene; Benzo (a) Anthracene; and Perylene are 11,803; 0.695; 5.786; 5.786; 5.788; 5.794; 7.0796 and 7.092 ppm, respectively. Limit of detection (LoD), limit of quantification (LoQ), linearity and linear range can be used to determine the concentration of PAH in sediment samples.Keywords: Validation Method, Concentration, PAH, Sediments

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Barros, G., D. García, S. Oviedo, M. Ramirez, A. Torres e S. Chulze. "Deoxynivalenol and nivalenol analysis in soybean and soy flour". World Mycotoxin Journal 1, n. 3 (1 agosto 2008): 263–66. http://dx.doi.org/10.3920/wmj2008.1052.

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A rapid and accurate method of quantifying deoxynivalenol (DON) and nivalenol (NIV) in soybean and soy flour is described. The samples were extracted with acetonitrile:water (84:16, v/v) and cleaned through a solidphase extraction (SPE) column. The mycotoxins were separated, detected and quantified by reversed-phase high performance liquid chromatography (HPLC) with UV detection (220 nm) using water:methanol (88:12, v/v) as mobile phase. Characteristics of this in-house method such as accuracy, precision and detection and quantification limits were defined by means of a recovery test with spiked soybean and soy flour samples. The detection limit (LOD) was 0.1 µg/g for DON and 0.2 µg/g for NIV, based on a signal-noise ratio 3:1. Quantification limit (LOQ) was established as three times the detection limit.

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Yang, Wan Qi, Xin Lu, Fu Sheng Li e Yan Chun Zhao. "Study on LOD of Trace Elements by XRF Analysis Using BP & Adaboost and PLS Methods". Advances in Science and Technology 105 (aprile 2021): 99–109. http://dx.doi.org/10.4028/www.scientific.net/ast.105.99.

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Poisonous elements such as Cd, Hg, Pb, As, Zn, Cr, Ni, Cu etc. are commonly observed in polluted soil and hard to be removed by soil microbes. It is of significant importance to identify these poisonous elements in-situ and accurately both in qualitative and quantitative sense. In order to determine the Limit of Detection (LOD) for trace elements (e.g. Cadmium) in polluted soil samples based on Energy Dispersion X-ray fluorescence (ED-XRF) spectroscopy, approximately 60 national standard soil samples were collected and measured by an XRF equipment. The authors firstly utilize the Method Detection Limit (MDL) algorithm to calculate the LOD of trace elements, and then develop a new model called Back Propagation Adaboost (BP & Adaboost) classification to determine the LOD based on a presumed tolerance error (e.g. 5%). Furthermore, the Multivariate- Partial Linear Squares Regression (M-PLSR) method is applied to regress the data and validate the LOD values. In this paper, the authors make a detailed comparison between the BP algorithm and the BP & Adaboost classification algorithm under different presumed detection limits, and it is found that the detection results achieved the best qualitative prediction of Cd element (i.e. whether it exists in soil) based on the BP & Adaboost algorithm. The experimental results indicate that the BP & Adaboost algorithm is the most effective method to determine and decrease the LOD of trace element (such as Cd) in soil. The advantages are: It combines the classification effects of several weak classifiers, and determines that the LOD of element Cd is 0.5mg/kg with prediction error rate of 5%. Compared with the traditional methods like MDL, it is proved that the BP & Adaboost algorithm is appropriate to be used in the terms of prediction accuracy. It is recommended that the BP & Adaboost classification method shall be used for material analysis on XRF spectroscopy.

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Sharma, Kusum, Noor Alam e S. S. Islam. "Inter-dependency between surface morphology and sensitive low RH detection: exploration of an intricate mechanism to extend the lower detection limit". Nanoscale Advances 2, n. 6 (2020): 2564–76. http://dx.doi.org/10.1039/d0na00047g.

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Ershadi, Saba, e Ali Shayanfar. "Are LOD and LOQ Reliable Parameters for Sensitivity Evaluation of Spectroscopic Methods?" Journal of AOAC INTERNATIONAL 101, n. 4 (1 luglio 2018): 1212–13. http://dx.doi.org/10.5740/jaoacint.17-0363.

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Abstract The limit of detection (LOD) and the limit of quantification (LOQ) are common parameters to assess the sensitivity of analytical methods. In this study, the LOD and LOQ of previously reported terbium sensitized analysis methods were calculated by different methods, and the results were compared with sensitivity parameters [lower limit of quantification (LLOQ)] of U.S. Food and Drug Administration guidelines. The details of the calibration curve and standard deviation of blank samples of three different terbium-sensitized luminescence methods for the quantification of mycophenolic acid, enrofloxacin, and silibinin were used for the calculation of LOD and LOQ. A comparison of LOD and LOQ values calculated by various methods and LLOQ shows a considerable difference. The significant difference of the calculated LOD and LOQ with various methods and LLOQ should be considered in the sensitivity evaluation of spectroscopic methods.

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Franko, Mladen, Dane Bicanic, Zoltán Bozóki e Henk Jalink. "Dual-Beam Thermal Lens Measurement of Condensed-Phase Sample at CO2 Laser Wavelengths: Detection of Octadecanoic Acid in Carbon Tetrachloride". Applied Spectroscopy 48, n. 12 (dicembre 1994): 1457–60. http://dx.doi.org/10.1366/0003702944027868.

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Detection of monobasic, straight-chain saturated fatty acid (octadecanoic C18:0) in CCl4, based on the thermal lens effect after excitation by CO2 laser radiation at 934.9 cm−1, is described for the first time. The achieved limit of detection (LOD = 0.3%) is comparable to that of the transmission infrared technique. Possibilities for further improvements in sensitivity and detection limit are also discussed.

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Marjanovic, Nikola, Snezana Kravic, Zvonimir Suturovic e Jaroslava Svarc-Gajic. "Determination of sensitivity limit in quantative analysis of polycyclic aromatic hydrocarbons by Gc-ms". Acta Periodica Technologica, n. 35 (2004): 111–19. http://dx.doi.org/10.2298/apt0435111m.

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The limit of detection (LOD) and the limit of quantitation (LOQ) for 16 individual PAHs from the Environmental Protection Agency (EPA) list (naphthalene, acenaphthylene, acenaphtene, fluorene, phenanthrene antrachene, fluoranthene, pyrene, benzo(a)anthracene, chrysene benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, dibenzo(a,h) anthracene, benzo(g,h,i)perylene and indeno(1,2,3-cd)pyrene) were determined by Gas Chromatography ? Mass Spectrometry (GC-MS). Determination was performed by SCAN (digital linear scanning) and SIM (selected ion monitoring) techniques preceded by the optimization of the experimental factors. The limit of detection obtained by the SCAN technique was in the range of 0.179 ? 15.236 ng, and the quantitation limit in the range of 1.017 ? 50.788 ng. SIM technique enabled LOD and LOQ in the range of 0.036 ? 13.886 pg and 0.119 ? 46.287 pg respectively.

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Wang, Yan, Guang He Wu, Wei Sheng, Yan Zhang, Meng Yuan e Shuo Wang. "Rapid Determination of Fumonisin B1 in Food Samples by a Clean-Up Tandem Immunoassay Column". Advanced Materials Research 488-489 (marzo 2012): 1568–73. http://dx.doi.org/10.4028/www.scientific.net/amr.488-489.1568.

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An immunochemistry-based assay for non-instrumental simultaneous detection of fumonisins in food was developed. The method was based upon the direct competitive immuno-reaction and the horse radish peroxidase enzymatic reaction. The assay was developed to show a visual detection result, according to a yes/no response to the LOD of fumonisins. The limit of detection (LOD) was 40 μg L-1. The assay could be accomplished within 15 min in all and 4 min for chromogenic substrate application. The fumonisin contaminations in different kinds of food were analyzed by the proposed method and the results were confirmed by ELISA. Avoiding time-consuming reaction steps and complicated pre-treatment procedures, this assay was demonstrated as a promising tool for on-site sample detections.

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Xu, Xiaoxin, Li Sun, Zhongxing Wang, Lingling Guo, Xinxin Xu, Aihong Wu, Hua Kuang, Shanshan Song e Chuanlai Xu. "Hapten synthesis and antibody production for the development of a paper immunosensor for lean meat powder zilpaterol". New Journal of Chemistry 45, n. 11 (2021): 5228–39. http://dx.doi.org/10.1039/d1nj00426c.

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An anti-zilpaterol mAb with an IC₅₀ of 0.31 ng mL⁻¹ and a limit of detection (LOD) of 0.02 ng mL⁻¹ has been developed. For semi-quantitative detection in pork samples, the visual LOD is 0.5 ng mL⁻¹ and the cut-off value is 5 ng mL⁻¹.

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Qiao, Jie, Siyu Lin, Wenli Sun, Lixin Ma e Yi Liu. "A method for the quantitative detection of Cas12a ribonucleoproteins". Chemical Communications 56, n. 83 (2020): 12616–19. http://dx.doi.org/10.1039/d0cc04019c.

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We developed a method for the rapid and quantitative detection of the effective Cas12a RNPs by the combined use of anti-CRISPR protein AcrVA1 and stem-loop RT-qPCR, achieving a limit of detection (LOD) of 1 fM.

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Xing, Haibo, Xuelian Fei, Bowen Zheng, Xiyin Zheng, Xu Dang, Hongbo Zhang, Fuxiang Tian, Xiang Mei e Xiaojun Hu. "Aptamer-Facilitated Design of Gold Nanoparticle-Based Logic Gates for Cyromazine and Melamine Detection in Milk". Australian Journal of Chemistry 74, n. 8 (2021): 574. http://dx.doi.org/10.1071/ch21011.

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In this paper, we developed a simply designed detection method for logic gates by using aptamers, cetyltrimethyl ammonium bromide, together with melamine and cyromazine to control the aggregation and dispersion of gold nanoparticles (AuNPs). First, either melamine or cyromazine can induce the aggregation of AuNPs, supporting an OR gate to detect whether they were present or not. Second, based on the fact that aptamer T31 can specifically bind with melamine, preventing the aggregation of AuNPs, an improved INHIBIT gate was also fabricated to find whether there was melamine. It has a detection limit of 0.12ppm by the naked eye for the detection of melamine, and the limit of detection (LOD) by spectrophotometer is 2.2ppb. Third, with the adsorption of aptamer Tcy1 on AuNPs and the strong coordination of Tcy1 with cyromazine, the addition of cyromazine and CTAB immediately resulted in the aggregation of AuNPs, giving rise to an AND gate. This gate has a detection limit of 0.17ppm by the naked eye and the limit of detection (LOD) is 9.0ppb by spectrophotometer. The system provided a good platform for the development of functional logic systems.

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Dołowy, Małgorzata, Katarzyna Kulpińska-Kucia e Alina Pyka. "Validation of a Thin-Layer Chromatography for the Determination of Hydrocortisone Acetate and Lidocaine in a Pharmaceutical Preparation". Scientific World Journal 2014 (2014): 1–10. http://dx.doi.org/10.1155/2014/107879.

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A new specific, precise, accurate, and robust TLC-densitometry has been developed for the simultaneous determination of hydrocortisone acetate and lidocaine hydrochloride in combined pharmaceutical formulation. The chromatographic analysis was carried out using a mobile phase consisting of chloroform + acetone + ammonia (25%) in volume composition 8 : 2 : 0.1 and silica gel 60F254plates. Densitometric detection was performed in UV at wavelengths 200 nm and 250 nm, respectively, for lidocaine hydrochloride and hydrocortisone acetate. The validation of the proposed method was performed in terms of specificity, linearity, limit of detection (LOD), limit of quantification (LOQ), precision, accuracy, and robustness. The applied TLC procedure is linear in hydrocortisone acetate concentration range of3.75÷12.50 μg·spot−1, and from1.00÷2.50 μg·spot−1for lidocaine hydrochloride. The developed method was found to be accurate (the value of the coefficient of variation CV [%] is less than 3%), precise (CV [%] is less than 2%), specific, and robust. LOQ of hydrocortisone acetate is 0.198 μg·spot−1and LOD is 0.066 μg·spot−1. LOQ and LOD values for lidocaine hydrochloride are 0.270 and 0.090 μg·spot−1, respectively. The assay value of both bioactive substances is consistent with the limits recommended by Pharmacopoeia.

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Kim, Yonghee, Abdurhaman Teyib Abafogi, Buu Minh Tran, Jaewon Kim, Jinyeop Lee, Zhenzhong Chen, Pan Kee Bae et al. "Integrated Microfluidic Preconcentration and Nucleic Amplification System for Detection of Influenza A Virus H1N1 in Saliva". Micromachines 11, n. 2 (16 febbraio 2020): 203. http://dx.doi.org/10.3390/mi11020203.

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Influenza A viruses are often present in environmental and clinical samples at concentrations below the limit of detection (LOD) of molecular diagnostics. Here we report an integrated microfluidic preconcentration and nucleic amplification system (μFPNAS) which enables both preconcentration of influenza A virus H1N1 (H1N1) and amplification of its viral RNA, thereby lowering LOD for H1N1. H1N1 virus particles were first magnetically preconcentrated using magnetic nanoparticles conjugated with an antibody specific for the virus. Their isolated RNA was amplified to cDNA through thermocycling in a trapezoidal chamber of the μFPNAS. A detection limit as low as 100 TCID50 (50% tissue culture infective dose) in saliva can be obtained within 2 hours. These results suggest that the LOD of molecular diagnostics for virus can be lowered by systematically combining immunomagnetic separation and reverse transcriptase-polymerase chain reaction (RT-PCR) in one microfluidic device.

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Stevenson, Christopher L., e James D. Winefordner. "Estimating Detection Limits in Ultratrace Analysis. Part II: Detecting and Counting Atoms and Molecules". Applied Spectroscopy 46, n. 3 (marzo 1992): 407–19. http://dx.doi.org/10.1366/0003702924125249.

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Although the limit of detection (LOD) is a widely used means of indicating the detection power of an analytical technique, the application of conventional detection limit theory is not straightforward with respect to laser spectroscopic methods which are capable of detecting single atoms or molecules in the laser beam. In this paper, theoretical considerations in the detection and evaluation of these methods are addressed on the basis of a simple model of a typical laser spectroscopic experiment; in addition, the theoretical requirements for the precise counting of atoms, and factors which influence the signal variance in the model, are considered. Simple Monte Carlo computer simulations are used to verify and demonstrate the application of the theory of single atom detection (SAD) to typical experimental situations.

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Le Thi, Lien, Anh Bach Thuy, Khanh Cao Cong, Ha Tran Nguyen e Hong Hao Le Thi. "Determination of crinamidine in dietary supplements by GC-MS/MS". Heavy metals and arsenic concentrations in water, agricultural soil, and rice in Ngan Son district, Bac Kan province, Vietnam 1, n. 1 (9 marzo 2018): 3–7. http://dx.doi.org/10.47866/2615-9252/vjfc.48.

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The determination of crinamidine in dietary supplements content by mass spectrometry (GC-MS/MS) was developed and validated. The method was performed on the DB5MS column (30m x 0,25mm; 0,25 μm), in combination with the tandem mass spectrometry. The parameters of the method were evaluated for selectivity, calibration curve, accuracy, precision, limit of detection (LOD) and limit of quantification (LOQ). The calibration curve was highly linear (the coefficient of determination 0.9970) within the concentration range of 5ppm-50ppm. The recovery at three concentrations were above 90,1%. The limit of detection (LOD) and limit of quantification (LOQ) of the methods were 3 and 10 mg/kg, respectively. All obtained results were acceptable according to the AOAC for dietary supplements. The method was applied to analyze 34 samples in Hanoi.

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Parachalil, Drishya Rajan, Deirdre Commerford, Franck Bonnier, Igor Chourpa, Jennifer McIntyre e Hugh J. Byrne. "Raman spectroscopy as a potential tool for label free therapeutic drug monitoring in human serum: the case of busulfan and methotrexate". Analyst 144, n. 17 (2019): 5207–14. http://dx.doi.org/10.1039/c9an00801b.

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Abstract (sommario):

A methodology is proposed, based on Raman spectroscopy coupled with multivariate analysis, to determine the Limit of Detection (LOD) and Limit of Quantification (LOQ) for therapeutic drug monitoring in human serum, using the examples of Busulfan and Methotrexate.

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Ghasemi, Farshid, Maysamreza Chamanzar, Ali A. Eftekhar e Ali Adibi. "An efficient technique for the reduction of wavelength noise in resonance-based integrated photonic sensors". Analyst 139, n. 22 (2014): 5901–10. http://dx.doi.org/10.1039/c4an01292e.

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Jing, Jianying, Kun Liu, Junfeng Jiang, Tianhua Xu, Shuang Wang, Jinying Ma, Zhao Zhang, Wenlin Zhang e Tiegen Liu. "Double-Antibody Sandwich Immunoassay and Plasmonic Coupling Synergistically Improved Long-Range SPR Biosensor with Low Detection Limit". Nanomaterials 11, n. 8 (22 agosto 2021): 2137. http://dx.doi.org/10.3390/nano11082137.

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A long-range surface plasmonic resonance (LR-SPR) biosensor modified with double-antibody sandwich immunoassay and plasmonic coupling is demonstrated for human-immunoglobulin G detection with a low limit of detection (LOD). The double-antibody sandwich immunoassay dramatically changes the average refractive index of the medium layer on the sensor surface. The near-field electron coupling between the localized surface plasmon and the long-range surface plasmon leads to a significant perturbation of the evanescent field. The large penetration depth and the long propagation distance of the long-range surface plasmonic waves facilitate the LR-SPR sensor in the detection of biological macromolecules. The unique light absorption characteristic of the nanocomposite material in the sensor provides the in situ self-compensation for the disturbance. Therefore, besides the inherent advantages of optical fiber sensors, the developed biosensor can realize the detection of biomolecules with high sensitivity, low LOD and high accuracy and reliability. Experimental results demonstrate that the LOD of the biosensor is as low as 0.11 μg/mL in the detection of the phosphate-buffered saline sample, and the spike-and-repetition rate is 105.56% in the detection of the real serum sample, which partly shows the practicability of the biosensor. This indicates that the LR-SPR biosensor provides better response compared with existing similar sensors and can be regarded as a valuable method for biochemical analysis and disease detection.

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Tanwar, Arvin Sain, Sourabh Patidar, Saurabh Ahirwar, Sourav Dehingia e Parameswar Krishnan Iyer. "“Receptor free” inner filter effect based universal sensors for nitroexplosive picric acid using two polyfluorene derivatives in the solution and solid states". Analyst 144, n. 2 (2019): 669–76. http://dx.doi.org/10.1039/c8an01970c.

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Abstract (sommario):

“Receptor free” and “interaction free” detection of nitroexplosive PA at remarkably low limit of detection (LOD) values of 110 nM and 219 nM using two new fluorescent polymers via the inner filter effect mechanism.

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28

Gowtham Reddy Cheruku, Sai Laasya Mithinti e Purushotham Saidu. "UV Spectrophotometric Method Development and Validation of Esomeprazole in Bulk and Pharmaceutical Dosage Forms". International Journal of Research in Pharmaceutical Sciences 12, n. 3 (22 settembre 2021): 2286–90. http://dx.doi.org/10.26452/ijrps.v12i3.4855.

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Abstract (sommario):

The work discusses method development and validation. An uncomplicated, accurate, and straightforward method was developed for the drug Esomeprazole in bulk as well as Pharmaceutical dosage form. NaOH was used as the solvent. The maximum wavelength (ʎ max) for Esomeprazole was found to be 305nm. The validation was performed as per International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH) guidelines for Accuracy linearity, precision, Limit of Detection (LOD) and Limit of Quantification (LOQ). Esomeprazole's recovery percentage (%) was 100.20%, respectively. Linearity for Esomeprazole was observed between 5-25µg/ml, respectively. Regression equation y=0.0407x-0.0122, regression coefficient (r²) is 0.9963 for Esomeprazole. Inter day and intraday precision were checked, % relative standard deviation values were less than 2. The regression equations were used to derive the Limit of Detection (LOD) and Limit of Quantification (LOQ) values. LOD value was found to be 0.734 µg/mL and LOQ value was 2.224 µg/mL for Esomeprazole. The assay of the marketed formulation was performed, which was between 98-102%. So the method developed was simple and economical that can be adopted for routine tests.

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29

Napitupulu, Rona Maningting, Dirgarini Julia e Aman S. Panggabean. "Validasi Metode Penentuan Mn Dalam Oli Lubrikan Dengan Metode Pengenceran Langsung Menggunakan Spektrofotometer Serapan Atom". Indo. J. Chem. Res. 6, n. 2 (31 gennaio 2019): 94–100. http://dx.doi.org/10.30598//ijcr.2019.6-ama.

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Abstract (sommario):

Validation method on the determination of Mn in lubricating oil by direct dilution method using Atomic Absorption Spectrophotometer (AAS) in Laboratory & Environment Control PT. Badak NGL Bontang has been done The validation method was done with research stages such as determination of optimum solvent, and determination of some important parameters influential for validation method such as parameter of liniearitas (r), Instrument Detection Limit (IDL), Methode Detection Limit (MDL), accuracy, precision, Limit of Detection(LOD) and Limit of Quantitation(LOQ). The result of research obtain is good, showed that the linearity value with R2 ≥ 0,997. The IDL and MDL value was 0.0021 ppm and 0.0092 ppm respectively and has been acceptability requirements of MDL. The accuracy paramater obtained recovery value with range 82.25-88.34%. The measurement of repeatability and reproducibility, the CV Horwitz value smaller than % RSD, indicating the method had a good precision. The measurement of LOD and LOQ value was 0.095 ppm 0.317 ppm respectively. Based on the result of the research determination method of Mn in lubricating oil by direct dilution method using AAS concluded valid.

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30

Zhang, Jianjian, Chuwen Li, Rui Zhang, Fengyuan Zhang, Wei Liu, Xiaoyan Liu, Simon Ming-Yuen Lee e Haixia Zhang. "A phosphinate-based near-infrared fluorescence probe for imaging the superoxide radical anion in vitro and in vivo". Chemical Communications 52, n. 13 (2016): 2679–82. http://dx.doi.org/10.1039/c5cc09976e.

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Abstract (sommario):

A novel near-infrared (NIR), turn-on fluorescence probeCyRcontaining a phosphinate group as a recognizing moiety for the selective detection of O₂˙⁻with a low limit of detection (LOD, 9.9 nM) was developed.

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31

Pyun, Jae-Chul, Joachim Jose e Min Park. "Development of a wash-free immunoassay using Escherichia coli cells with autodisplayed Z-domains". Analyst 142, n. 10 (2017): 1720–28. http://dx.doi.org/10.1039/c6an02386j.

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32

Patyra, Ewelina, Monika Przeniosło-Siwczyńska e Krzysztof Kwiatek. "Determination of Sulfonamides in Feeds by High-Performance Liquid Chromatography after Fluorescamine Precolumn Derivatization". Molecules 24, n. 3 (28 gennaio 2019): 452. http://dx.doi.org/10.3390/molecules24030452.

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Abstract (sommario):

A new multi-residue method for the analysis of sulfonamides (sulfadiazine, sulfamerazine, sulfamethazine, sulfaguanidine and sulfamethoxazole) in non-target feeds using high-performance liquid chromatography-fluorescence detection (HPLC-FLD) and precolumnderivatization was developed and validated. Sulfonamides (SAs) were extracted from feed with an ethyl acetate/methanol/acetonitrile mixture. Clean-up was performed on a Strata-SCX cartridge. The HPLC separation was performed on a Zorbax Eclipse XDB C18 column with a gradient mobile phase system of acetic acid, methanol, and acetonitrile. The method was validated according to EU requirements (Commission Decision 2002/657/EC). Linearity, decision limit, detection capability, detection and quantification limits, recovery, precision, and selectivity were determined, and adequate results were obtained. Using the HPLC-FLD method, recoveries were satisfactory (79.3–114.0%), with repeatability and reproducibility in the range of 2.7–9.1% to 5.9–14.9%, respectively. Decision limit (CCα) and detection capability (CCβ) were 197.7–274.6 and 263.2–337.9 µg/kg, respectively, and limit of detection (LOD) and limit of quantification (LOQ) were 34.5–79.5 and 41.3–89.9 µg/kg, respectively, depending on the analyte. Results showed that this analytical procedure is simple, rapid, sensitive, and suitable for the routine control of feeds.

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Seğmenoğlu, Mansur Seymen, e Emine Baydan. "Comparison of Heavy Metal Levels of Organic and Conventional Milk and Milk Products in Turkey". Turkish Journal of Agriculture - Food Science and Technology 9, n. 4 (24 aprile 2021): 696–700. http://dx.doi.org/10.24925/turjaf.v9i4.696-700.4007.

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Abstract (sommario):

This study aimed to determine and compare aluminum (Al), arsenic (As), cadmium (Cd), and lead (Pb) levels in conventional and organic milk, white cheese, and butter samples which are sold in the markets of Turkey. Within the scope of the study, totally 72 samples (36 for organic, and 36 for conventional) were collected, and analyzed between March 2010 and February 2011. After the samples were burned by microwave burning, element measurements were performed on atomic absorption spectrophotometer (AAS) device. As a result of the study, on the 49 samples (29 conventional, 20 organic) of the 72 collected product, element levels were determined above the limit of detection (LOD) (0.02 ppm). Pb and Al were the most common elements above the LOD. However, milk samples with a Pb level above the LOD still remained below the limit reported by the Turkish Food Codex Regulation for Contaminants. Since Turkish Food Codex Regulation does not have legal limits for Al, As, Cd and Pb for dairy products (cheese and butter), it was accepted as safe in terms of Al, As, Cd and Pb according to food limits in Turkish Food Codex and ADI values of FAO / WHO.

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Almeida, Mariana O., Silvia Catarina S. Oloris, Vanessa Heloisa F. Faria, Márcia Cassimira M. Ribeiro, Daniel M. Cantini e Benito Soto-Blanco. "Optimization of Method for Pesticide Detection in Honey by Using Liquid and Gas Chromatography Coupled with Mass Spectrometric Detection". Foods 9, n. 10 (26 settembre 2020): 1368. http://dx.doi.org/10.3390/foods9101368.

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Abstract (sommario):

This study aimed to optimize and validate a multi-residue method for identifying and quantifying pesticides in honey by using both gas and liquid chromatographic separation followed by mass spectrometric detection. The proposed method was validated to detect 168 compounds, 127 of them by LC-MS/MS (liquid chromatography tandem mass spectrometric detection) and 41 by GC-MS/MS (gas chromatography tandem mass spectrometric detection). The limit of detection (LOD) and limit of quantification (LOQ) values for the analytes determined by LC-MS/MS were 0.0001–0.0004 mg/kg and 0.0002–0.0008 mg/kg, respectively. For GC-MS/MS analyses, the LOD and LOQ values were 0.001–0.004 mg/kg and 0.002–0.008 mg/kg. In total, 33 samples of commercial honey produced by apiaries in six Brazilian states were analyzed with the validated method. Residual amounts of 15 analytes were detected in 31 samples (93.9%). The method described in the present study was able to detect an extensive and broad range of pesticides with very high sensitivity.

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35

Karapetis, Stefanos, Dimitrios Nikolelis e Tibor Hianik. "Label-Free and Redox Markers-Based Electrochemical Aptasensors for Aflatoxin M1 Detection". Sensors 18, n. 12 (1 dicembre 2018): 4218. http://dx.doi.org/10.3390/s18124218.

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Abstract (sommario):

We performed a comparative analysis of the sensitivity of aptamer-based biosensors for detection mycotoxin aflatoxin M1 (AFM1) depending on the method of immobilization of DNA aptamers and method of the detection. Label-free electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV) for ferrocene labeled neutravidin layers were used for this purpose. Amino-modified DNA aptamers have been immobilized at the surface of polyamidoamine dendrimers (PAMAM) of fourth generation (G4) or biotin-modified aptamers were immobilized at the neutravidin layer chemisorbed at gold surface. In the first case the limit of detection (LOD) has been determined as 8.47 ng/L. In the second approach the LOD was similar 8.62 ng/L, which is below of allowable limits of AFM1 in milk and milk products. The aptasensors were validated in a spiked milk samples with good recovery better than 78%. Comparative analysis of the sensitivity of immuno- and aptasensors was also performed and showed comparable sensitivity.

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36

Jovanovic, Slobodan V., Thomas Zakharov, Hemendra Mulye, Duck Kim e Kelly-Anne Fagan. "Determination of hydrazine at Ontario nuclear power plants". Analytical Methods 7, n. 23 (2015): 9825–34. http://dx.doi.org/10.1039/c5ay02178b.

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Abstract (sommario):

In this study, we developed and validated a sensitive method for the determination of hydrazine in water samples using ion chromatography coupled with an amperometric detector (limit of detection (LOD) = 0.02 μg L⁻¹ and limit of quantification (LOQ) = 0.1 μg L⁻¹).

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37

Palmieri, Raffaele, Alfonso Piciocchi, Valentina Arena, Luca Maurillo, Maria Ilaria Del Principe, Giovangiacinto Paterno, Tiziana Ottone et al. "Clinical Relevance of- Limit of Detection (LOD) - Limit of Quantification (LOQ) - Based Flow Cytometry Approach for Measurable Residual Disease (MRD) Assessment in Acute Myeloid Leukemia (AML)". Blood 136, Supplement 1 (5 novembre 2020): 37–38. http://dx.doi.org/10.1182/blood-2020-139557.

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Abstract (sommario):

Background: In Acute Myeloid Leukemia (AML), identification of measurable residual disease (MRD) thresholds with clinical significance is still a matter of debate. For this purpose, multiparametric flow cytometry (MFC) is extensively employed for MRD quantification, due to high sensitivity (down to 1:10-3/10-5 cells) and wide applicability (up to 90% of cases). The identification of 20 clustered residual leukemic cells seems sufficient for the recognition of MRD presence (lower limit of detection [LOD]), whereas a cluster of 50 events may be the minimum threshold for the quantification of a cell population (lower limit of quantitation [LOQ]), provided a sufficient denominator of relevant events (500'000-1'000'000) is acquired. Methods: Using a MFC assay, we assessed the predictive power of a threshold calculated applying the criteria of LOD and LOQ on 261 intensively treated AML patients enrolled in the GIMEMA AML1310 prospective trial.According to the protocol design, patients with a bone marrow residual leukemic cells count (RLCc) equal or above 0.035% of the total no. of mononuclear (MNC) cells qualified as MRDpos,, whileusing LOD and LOQ, we selected the following categories of patients: 1) LODneg if RLCc was below LOD (20x100/total no. of events); 2) LODpos-LOQneg if RLCc was between LOD and LOQ; and 3) LOQpos if RLCc was above LOQ (50x100/total no. of events). Results: The ELN target of 500'000 events was reached in 182/261 (69.6%) patients. Overall, using the predefined AML1310 protocol MRD threshold, 154 (59%) and 107 (41%) were MRDneg and MRDpos, respectively, whereas 74 (28.4%), 43 (16.5%) and 144 (54.4%) patients were classified as LODneg, LODpos-LOQneg and LOQpos, respectively. Two-year overall survival (OS) was 75.4% vs. 79.8% vs. 66.4% for LODneg, LODpos-LOQneg and LODpos, respectively (p=0.1197), and 74.5% vs. 66.4% according to AML1310 protocol 0.035% threshold for MRDneg and MRDpos patients, respectively (p=0.3521). Due to superimposable outcome, LOD-LOQneg and LODpos-LOQneg categories were combined. Accordingly, LODneg/LODpos-LOQneg and LOQpos groups clearly differed in terms of OS (77% vs. 66.4%, p=0.0437) [FIGURE 1A]. Such a figure was challenged in multivariate analysis (p=0.048, HR 0.628, 95% CI 0.396-0.997) that confirmed the independent role of LOD-LOQ approach in influencing OS. To enhance the predictivity of LOD-LOQ estimate, we then focused on samples acquisition of which passed the 500'000 events, according to ELN guidelines. Among 182/261 (69.7%) cases with > 500'000 MNC events as denominator, LODneg/LODpos-LOQneg and LOQpos subgroups were clearly distinct in terms of OS (2-years OS of 83.5% vs. 69.4%, p=0.009). [FIGURE 1B] Similarly, also when selecting those patients (158/261 [60.5%]) whose acquisition passed 500'000 CD45+ events, LODneg/LODpos-LOQneg and LOQpos showed a different behavior with 2-years OS of 86.7% vs. 69.0%, respectively (p=0.004). [FIGURE 1C] Finally, when considering the interaction of the 3 LOD-LOQ categories with possible post-remissional strategies, LODneg/LODpos-LOQneg patients submitted to autologous stem cell transplant showed the best 2-years OS (88.9%) as compared to all the other categories (allogeneic stem cells transplant and no graft-based treatments) (p=0.026). Summary/Conclusion: In conclusion, the use of LOD-LOQ method results in a more sensitive detection of MRD that, in turn, translates in a more accurate recognition of patients with different prognosis. Actually, such an approach allowed to dissect even further the category of patients called MRDneg according to the AML1310 protocol definition, since MRDneg subjects who belonged to a "true negative" LOD-LOQ sub-group [LODneg/LODpos-LOQneg] had a better outcome than the other MRDneg ones. This MRD approach could serve as a useful tool to personalize post-remission strategy in intensively treated AML patients, through selection of high-quality remission patients who may benefit from less intensive post-consolidation therapies. Disclosures Voso: Bristol Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Venditti:Novartis: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); Pfizer: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company), Speakers Bureau; Amgen: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); Jazz: Consultancy, Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company); AbbVie: Consultancy, Honoraria, Other: TRAVEL, ACCOMODATIONS, EXPENSES (paid by any for-profit health care company); Janssen: Consultancy, Honoraria, Other: TRAVEL, ACCOMODATIONS, EXPENSES (paid by any for-profit health care company).

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Ruecker, Norma J., Rebecca M. Hoffman, Rachel M. Chalmers e Norman F. Neumann. "Detection and Resolution of Cryptosporidium Species and Species Mixtures by Genus-Specific Nested PCR-Restriction Fragment Length Polymorphism Analysis, Direct Sequencing, and Cloning". Applied and Environmental Microbiology 77, n. 12 (15 aprile 2011): 3998–4007. http://dx.doi.org/10.1128/aem.02706-10.

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Abstract (sommario):

ABSTRACTMolecular methods incorporating nested PCR-restriction fragment length polymorphism (RFLP) analysis of the 18S rRNA gene ofCryptosporidiumspecies were validated to assess performance based on limit of detection (LoD) and for detecting and resolving mixtures of species and genotypes within a single sample. The 95% LoD was determined for seven species (Cryptosporidium hominis,C. parvum,C. felis,C. meleagridis,C. ubiquitum,C. muris, andC. andersoni) and ranged from 7 to 11 plasmid template copies with overlapping 95% confidence limits. The LoD values for genomic DNA from oocysts on microscope slides were 7 and 10 template copies forC. andersoniandC. parvum, respectively. The repetitive nested PCR-RFLP slide protocol had an LoD of 4 oocysts per slide. When templates of two species were mixed in equal ratios in the nested PCR-RFLP reaction mixture, there was no amplification bias toward one species over another. At high ratios of template mixtures (>1:10), there was a reduction or loss of detection of the less abundant species by RFLP analysis, most likely due to heteroduplex formation in the later cycles of the PCR. Replicate nested PCR was successful at resolving many mixtures ofCryptosporidiumat template concentrations near or below the LoD. The cloning of nested PCR products resulted in 17% of the cloned sequences being recombinants of the two original templates. Limiting-dilution nested PCR followed by the sequencing of PCR products resulted in no sequence anomalies, suggesting that this method is an effective and accurate way to study the species diversity ofCryptosporidium, particularly for environmental water samples, in which mixtures of parasites are common.

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Liu, Yongfeng, Xiaosheng Tang, Tao Zhu, Ming Deng, Iroegbu Paul Ikechukwu, Wei Huang, Guolu Yin et al. "All-inorganic CsPbBr3 perovskite quantum dots as a photoluminescent probe for ultrasensitive Cu2+ detection". Journal of Materials Chemistry C 6, n. 17 (2018): 4793–99. http://dx.doi.org/10.1039/c8tc00249e.

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Abstract (sommario):

Pollutions caused by heavy metals has become a wordwide concerned issue. Herein, CsPbBr₃ perovskite quantum dots are used as fluorescent probe for selective detection of copper ions in organic phase with a limit of detection (LOD) down to 0.1 nM.

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40

Brown, Richard J. C. "The Use and Abuse of Limits of Detection in Environmental Analytical Chemistry". Scientific World JOURNAL 8 (2008): 796–801. http://dx.doi.org/10.1100/tsw.2008.107.

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Abstract (sommario):

The limit of detection (LoD) serves as an important method performance measure that is useful for the comparison of measurement techniques and the assessment of likely signal to noise performance, especially in environmental analytical chemistry. However, the LoD is only truly related to the precision characteristics of the analytical instrument employed for the analysis and the content of analyte in the blank sample. This article discusses how other criteria, such as sampling volume, can serve to distort the quoted LoD artificially and make comparison between various analytical methods inequitable. In order to compare LoDs between methods properly, it is necessary to state clearly all of the input parameters relating to the measurements that have been used in the calculation of the LoD. Additionally, the article discusses that the use of LoDs in contexts other than the comparison of the attributes of analytical methods, in particular when reporting analytical results, may be confusing, less informative than quoting the actual result with an accompanying statement of uncertainty, and may act to bias descriptive statistics.

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He, Jin Zhe, Ming Lei e Pei Long Sun. "Study on LOD of Chinese Honey Adulterated with HFCS by HPAEC-PAD". Advanced Materials Research 718-720 (luglio 2013): 281–87. http://dx.doi.org/10.4028/www.scientific.net/amr.718-720.281.

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Abstract (sommario):

In consideration of the adulterated situation and characteristics of Chinese honey market, high performance anion exchange chromatography-pulsed amperometric detection (HPAEC-PAD) used for detection of high fructose corn syrup (HFCS) in adulterated honey were further studied in this paper, Isocratic elution with optimize chromatographic conditions, the limit of detection (LOD) of HFCS in adulterated acacia honey, linden honey, date honey and citrus honey can reached 1% respectively, while performed good reproducibility and high stability. This method was simple, effective, high sensitivity, and can be widely applied to the detection of honey with HFCS.

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Song, Jaewoo, Eunyoung Lee, Yula Jeon, Ji Eun Jang, Yundeok Kim, June-Won Cheong e Yoo Hong Min. "Improved Sensitivity and Discriminative Power of Factor FVIII Assay By Applying Turbidimetric Clotting Curve Analysis". Blood 124, n. 21 (6 dicembre 2014): 2853. http://dx.doi.org/10.1182/blood.v124.21.2853.2853.

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Abstract (sommario):

Abstract Background: The need for sensitive detection of coagulation factor between the levels of 0.0 and1.0% is now growing continuously. The most popular method of measuring factor VIII (FVIII) activity is one stage clotting time (activated partial thromboplastin time, APTT)-based assay. From the first and the second derivatives of the original turbidimetric curve, the velocity and acceleration of clot formation can be followed and parameters like maximum velocity (peak1) and acceleration (peak2) of clot formation can also be derived. We examined the limit of detection of FVIII activities measured based on clotting time, peak1 and peak2, following the recommendations from Clinical and Laboratory Standards Institute guideline. Method: We performed APTT with sample/reagent volume and incubation time modified to be identical to those adopted for factor assay on factor deficient plasma as blank and plasmas prepared to have variable FVIII activities from 0.1 to 1.6%. Peak1 and Peak2 were also measured to determine the limit of blank (LoB) and limit of detection (LoD) corresponding to each parameter. Also, by modifying the method of LoB and LoD determination, we determined lower limit of 1.0% (lower Lo1) corresponding to each parameter. Results: The mean clotting time of blank sample (FVIII 0.0%) was 131.4 ± 1.90 seconds (mean ± SD). Thus, 95% of clotting times measured from a blank sample (FVIII 0.0%) are longer than 128.3 seconds, which was determined to be the LoB for clotting time. The pooled standard deviation (SD) of clotting times measured from low FVIII samples was 2.29 seconds and 124.49 seconds which was the theoretically minimum value that was statistically different from LoB was set as the clotting time corresponding to LoD of FVIII. The LoD clotting time was between the clotting times of FVIII 0.2% and FVIII 0.4% sample and 0.4% was safely determined to be LoD of FVIII. This implied that plasma sample with at least 0.4% FVIII level was guaranteed to be measured higher than blank (FVIII 0.0%) sample. The mean peak1 height for blank sample was 21.4 ± 0.68 and LoB peak height was determined to be 22.53. The pooled SD for peak1 height was 0.68 and peak1 height of LoD was calculated to be 23.63. Because the mean peak1 height for 0.2% sample was 24.27, the LoD FVIII activity could be safely determined to be 0.2%. Thus, by applying peak1 as primary measure to estimate FVIII activity, the sensitivity of FVIII assay was increased with lower LoD of 0.2% compared with clotting time based assay. For peak2 height, LoB and LoD peak2 height were 14.86 and 18.59 respectively and The LoD could be set at FVIII 0.4%. Next, we determined lower Lo1, which meant FVIII level that was guaranteed to be measured significantly lower than 1.0% sample. For clotting time, lower Lo1 was FVIII 0.2% and for peak1 and 2 FVIII, was 0.4%. These results implied that by conventional clotting time based FVIII assay FVIII activity between 0.0 and 1.0% could not be measured credibly. FVIII should be at least 0.4% to be ever detected but ironically FVIII should be less than 0.2% to be assuredly measured lower than 1.0%. However, with peak1 there was an interval of FVIII value that could be assured to be measured higher than 0.0% but lower than 1.0%. Conclusion: We concluded that the maximum clotting velocity derived from turbidimetric curve analysis can be applied to measure FVIII activity between 0.0 and 1.0% credibly. Disclosures No relevant conflicts of interest to declare.

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Schneider, Sylvio, Martina Selig, Verena Keil, Matthias Lehmann, Andreas H. Foitzik, Mauro Casalboni e Maria Richetta. "Development of a Smartphone Based Reader for the Quantitative Analysis of Lateral Flow Assays". Materials Science Forum 941 (dicembre 2018): 2522–27. http://dx.doi.org/10.4028/www.scientific.net/msf.941.2522.

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Abstract (sommario):

Smartphones are developing into all-purposes devices. In the present work, the employment/application of smartphones as medical devices in home care and point-of-care (POC) diagnostics are investigated in the analysis of Lateral Flow Assays (LFA). A smartphone-based LFA reader was developed for the quantitative analysis of D-Dimer – a biomarker indicating e.g. thrombotic event or danger of embolism.The proof-of-concept has been shown with multiple smartphones in establishing: (I) Optimal dimensions of the LFA cell of 72.11mm distance of smartphone to D-Dimer test leading to a coefficients of variances (CV) between 0.8% and 4.2%. (II) Inter-device investigations: CVs around 13.5%; a limit of detection (LOD) of 100ng/ml (DDU) D-Dimer. (III) Inter-smartphone investigations: CV about 16%, a limit of detection (LOD) at 66.4ng/ml (DDU). (IV) Calibrations: CV and LOD of three smartphones are comparable to the commercial available LFA reader. Further development to put the multiple smartphone-based LFA reader on the market.

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Rotake, Dinesh, Anand Darji e Nitin Kale. "Ultrasensitive detection of cadmium ions using a microcantilever-based piezoresistive sensor for groundwater". Beilstein Journal of Nanotechnology 11 (18 agosto 2020): 1242–53. http://dx.doi.org/10.3762/bjnano.11.108.

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Abstract (sommario):

This paper proposes the selective and ultrasensitive detection of Cd(II) ions using a cysteamine-functionalized microcantilever-based sensor with cross-linked ᴅʟ-glyceraldehyde (DL-GC). The detection time for various laboratory-based techniques is generally 12–24 hours. The experiments were performed to create self-assembled monolayers (SAMs) of cysteamine cross-linked with ᴅʟ-glyceraldehyde on the microcantilever surface to selectively capture the targeted Cd(II). The proposed portable microfluidic platform is able to achieve the detection in 20–23 min with a limit of detection (LOD) of 0.56 ng (2.78 pM), which perfectly describes its excellent performance over other reported techniques. Many researchers used nanoparticle-based sensors for the detection of heavy metal ions, but daily increasing usage and commercialization of nanoparticles are rapidly expanding their deleterious effect on human health and the environment. The proposed technique uses a blend of thin-film and microcantilever (micro-electromechanical systems) technology, which mitigate the disadvantages of the nanoparticle approaches, for the selective detection of Cd(II) with a LOD below the WHO limit of 3 μg/L.

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Parker, Gail Abbott. "Validation of Methods Used in the Florida Department of Agriculture and Consumer Services' Chemical Residue Laboratory". Journal of AOAC INTERNATIONAL 74, n. 5 (1 settembre 1991): 868–71. http://dx.doi.org/10.1093/jaoac/74.5.868.

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Abstract Very few methods for detecting residues of pesticides in food or agricultural samples have undergone rigorous collaborative study and possess official AOAC status. The Chemical Residue Laboratory has formalized a method validation scheme to use when incorporating or developing new, unofficial methods. These methods are validated by assessing certain performance parameters: scope, specificity, linear range, accuracy, precision, limit of detection (LOD), and limit of quantitation (LOQ). For accuracy and precision assessment, 12 replicate fortifications must yield recoveries within the range of 70-120% with a coefficient of variation (CV) that compares favorably to the Horwitz CV. LOD and LOQ are equivalent to 3 and 10 times, respectively, the background signal contributed by a sample matrix blank. This criterion that we use for LOD/LOQ is not universal. In fact, because of differing definitions, we have encountered difficulties in enforcing a tolerance by using a registrant's method. This paper also presents an example of our method validation scheme, using a recent method development project for detecting sulfamethazine in raw milk. The sulfamethazine project also revealed unanticipated personnel problems, underscoring the importance of the human factor in quality assurance.

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Thakur, Deepika, Anshu Sharma, Dharmender Singh Rana, Nagesh Thakur, Dilbag Singh, Tomas Tamulevicius, Mindaugas Andrulevicius, Sigitas Tamulevicius, Sudheesh K. Shukla e Sourbh Thakur. "Facile Synthesis of Silver-Doped Zinc Oxide Nanostructures as Efficient Scaffolds for Detection of p-Nitrophenol". Chemosensors 8, n. 4 (3 novembre 2020): 108. http://dx.doi.org/10.3390/chemosensors8040108.

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In this paper, silver-doped zinc oxide nanoparticles were synthesized by using a solution combustion technique, in which zinc nitrate is used as an oxidizer and tartaric acid as a fuel. The phase composition, morphology and structural properties of the as-synthesized zinc oxide and silver-doped zinc oxide were established by using powdered X-ray diffraction, field emission scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy studies. Due to well-defined morphologies and crystallinity, the pure zinc oxide and silver-doped zinc oxide nanostructures can be used as efficient chemical sensors for the detection of p-nitrophenol (PNP). ZnO was found to show a low value of the limit of detection (LOD), i.e., 2.175 µM/L, for p-nitrophenol sensing; moreover, a sharp decrease in the limit of detection was observed with an increase in the concentration of silver ions, and the LOD value decreased to 0.669 µM/L for 10 mol % silver-doped zinc oxide. It is therefore concluded that Ag-doped ZnO shows a lower limit of detection as compared to pure ZnO for p-nitrophenol sensing.

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Yamamura, Kohji, Junichi Mano e Hiroyuki Shibaike. "Optimal definition of the limit of detection (LOD) in detecting genetically modified grains from heterogeneous grain lots". Quality Technology & Quantitative Management 16, n. 1 (10 luglio 2017): 36–53. http://dx.doi.org/10.1080/16843703.2017.1347992.

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SAAD ANTAKLI, Raghad Kabbani e And Rama Labban. "Analytical Spectrometric Study For Determining Dapagliflozin Propanediol Monohydrate Individually Or In Presence Of Metformin Hydrochloride In Tablets Formulation". JOURNAL OF ADVANCES IN CHEMISTRY 17 (10 settembre 2020): 80–87. http://dx.doi.org/10.24297/jac.v17i.8812.

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First simple spectrophotometric method was developed and applied to determine Dapagliflozin Propanediol Monohydrate by Zero Spectrophotometry and First Derivative Spectrophotometric method for determining of Dapagliflozin Propanediol Monohydrate (DAPA) in the presence of Metformin Hydrochloride (MET). Zero spectrophotometric (ZS) was applied for the determination of (DAPA) at 223.5 nm. Linearity range was (2.61– 31.23) µg/mL. Regression analysis showed a good correlation coefficients R2 = 0.9989. The limit of detection (LOD) and limit of quantification (LOQ) were to be 0.569 µg/mL and 1.724 µg/mL, respectively. Derivative spectrophotometric (1DS) was applied for the determination of (DAPA) in the presence (MET). (DAPA) was determined at 233 nm (1D233). Linearity ranges were (5.21 – 41.64) µg/mL for (DAPA). Regression analysis showed a good correlation coefficients R2 = 0.9994. The limit of detection (LOD) and limit of quantification (LOQ) were to be 0.732 µg/mL and 2.218 µg/mL for (DAPA). The proposed Zero spectrophotometry method was applied to analysis individual (DAPA), and the derivative (1D233) method was applied to analysis (DAPA) individually or with (MET) combination in Syrian trademark drugs.

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Boeckel, Jes-Niels, Lars Palapies, Tanja Zeller, Sophia M. Reis, Beatrice von Jeinsen, Stergios Tzikas, Christoph Bickel et al. "Estimation of Values below the Limit of Detection of a Contemporary Sensitive Troponin I Assay Improves Diagnosis of Acute Myocardial Infarction". Clinical Chemistry 61, n. 9 (1 settembre 2015): 1197–206. http://dx.doi.org/10.1373/clinchem.2015.238949.

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Abstract BACKGROUND The limit of detection (LoD) is the minimal amount of a substance that can be consistently detected. In the diagnosis of acute myocardial infarction (AMI) many patients present with troponin concentrations below the LoD of contemporary sensitive cardiac troponin I (cs-cTnI) assays. These censored values below the LoD influence the diagnostic performance of these assays compared to highly sensitive cTnI (hs-cTnI) assays. Therefore we assessed the impact of a new approach for interpolation of the left-censored data of a cs-cTnI assay in the evaluation of patients with suspected AMI. METHODS Our posthoc analysis used a real world cohort of 1818 patients with suspected MI. Data on cs-cTnI was available in 1786 patients. As a comparator the hs-cTnI version of the assay was used. To reconstruct quantities below the LoD of the cs-cTnI assay, a gamma regression approach incorporating the GRACE (Global Registry of Acute Coronary Events) score variables was used. RESULTS Censoring of cs-cTnI data below the LoD yielded weaker diagnostic information [area under the curve (AUC), 0.781; 95% CI, 0.731–0.831] regarding AMI compared to the hs-cTnI assay (AUC, 0.949; CI, 0.936–0.961). Use of our model to estimate cs-cTnI values below the LoD showed an AUC improvement to 0.921 (CI, 0.902–0.940). The cs-cTnI LoD concentration had a negative predictive value (NPV) of 0.950. An estimated concentration that was to be undercut by 25% of patients presenting with suspected AMI was associated with an improvement of the NPV to 0.979. CONCLUSIONS Estimation of values below the LoD of a cs-cTnI assay with this new approach improves the diagnostic performance in evaluation of patients with suspected AMI.

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Suryadi, Herman, Faatichatun Naja e Yahdiana Harahap. "DETECTION OF BISPHENOL A CONTAMINATION IN CANNED CARBONATED BEVERAGES BY GAS CHROMATOGRAPHY". International Journal of Applied Pharmaceutics 10, n. 1 (20 dicembre 2018): 116. http://dx.doi.org/10.22159/ijap.2018.v10s1.24.

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Objective: The purpose of this study was to develop sensitive, selective, and valid methods for the detection of bisphenol A (BPA) contamination inbeverage samples using gas chromatography (GC)-flame ionization.Methods: The optimized analysis system employed a long HP-1 capillary column (30 m, inner diameter 0.25 mm, film thickness 0.25 μm), gradientcolumn temperature (150°C–260°C at 10°C/min), and nitrogen as a carrier gas (1 mL/min). Samples were prepared for analysis using ethyl acetateas the extraction solvent.Results: This method yielded a linearity coefficient of 0.9998, while the limit of detection (LOD) and limit of quantitation (LOQ) were 0.287 μg/mL and0.956 μg/mL, respectively. All validation parameters, including linearity, selectivity, accuracy, precision, LOD, and LOQ, meet recognized acceptabilitycriteria. Contamination analysis showed that one of the three beverage brands tested contained 2.4090 μg/mL BPA, and contamination was evenhigher after heating.Conclusion: BPA contamination may occur in canned beverages, especially under improper storage conditions. This GC-based BPA detection systemmay be useful for the detection of BPA contamination in consumer beverages.

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