Bibliografie tematiche / Limit of Detection (LOD)

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Letteratura scientifica selezionata sul tema "Limit of Detection (LOD)"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 13 febbraio 2022

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Articoli di riviste sul tema "Limit of Detection (LOD)"

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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Più fonti

Tesi sul tema "Limit of Detection (LOD)"

Jin, Yan. "Bayesian Solution to the Analysis of Data with Values below the Limit of Detection (LOD)". University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1227293204.

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Rodríguez, Cuesta Mª José. "Limit of detection for second-order calibration methods". Doctoral thesis, Universitat Rovira i Virgili, 2006. http://hdl.handle.net/10803/9013.

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Analytical chemistry can be split into two main types, qualitative and quantitative. Most modern analytical chemistry is quantitative. Popular sensitivity to health issues is aroused by the mountains of government regulations that use science to, for instance, provide public health information to prevent disease caused by harmful exposure to toxic substances. The concept of the minimum amount of an analyte or compound that can be detected or analysed appears in many of these regulations (for example, to discard the presence of traces of toxic substances in foodstuffs) generally as a part of method validation aimed at reliably evaluating the validity of the measurements.

The lowest quantity of a substance that can be distinguished from the absence of that substance (a blank value) is called the detection limit or limit of detection (LOD). Traditionally, in the context of simple measurements where the instrumental signal only depends on the amount of analyte, a multiple of the blank value is taken to calculate the LOD (traditionally, the blank value plus three times the standard deviation of the measurement). However, the increasing complexity of the data that analytical instruments can provide for incoming samples leads to situations in which the LOD cannot be calculated as reliably as before.

Measurements, instruments and mathematical models can be classified according to the type of data they use. Tensorial theory provides a unified language that is useful for describing the chemical measurements, analytical instruments and calibration methods. Instruments that generate two-dimensional arrays of data are second-order instruments. A typical example is a spectrofluorometer, which provides a set of emission spectra obtained at different excitation wavelengths.

The calibration methods used with each type of data have different features and complexity. In this thesis, the most commonly used calibration methods are reviewed, from zero-order (or univariate) to second-order (or multi-linears) calibration models. Second-order calibration models are treated in details since they have been applied in the thesis.

Concretely, the following methods are described:
- PARAFAC (Parallel Factor Analysis)
- ITTFA (Iterative Target Transformation Analysis)
- MCR-ALS (Multivariate Curve Resolution-Alternating Least Squares)
- N-PLS (Multi-linear Partial Least Squares)

Analytical methods should be validated. The validation process typically starts by defining the scope of the analytical procedure, which includes the matrix, target analyte(s), analytical technique and intended purpose. The next step is to identify the performance characteristics that must be validated, which may depend on the purpose of the procedure, and the experiments for determining them. Finally, validation results should be documented, reviewed and maintained (if not, the procedure should be revalidated) as long as the procedure is applied in routine work.

The figures of merit of a chemical analytical process are 'those quantifiable terms which may indicate the extent of quality of the process. They include those terms that are closely related to the method and to the analyte (sensitivity, selectivity, limit of detection, limit of quantification, ...) and those which are concerned with the final results (traceability, uncertainty and representativity) (Inczédy et al., 1998). The aim of this thesis is to develop theoretical and practical strategies for calculating the limit of detection for complex analytical situations. Specifically, I focus on second-order calibration methods, i.e. when a matrix of data is available for each sample.

The methods most often used for making detection decisions are based on statistical hypothesis testing and involve a choice between two hypotheses about the sample. The first hypothesis is the "null hypothesis": the sample is analyte-free. The second hypothesis is the "alternative hypothesis": the sample is not analyte-free. In the hypothesis test there are two possible types of decision errors. An error of the first type occurs when the signal for an analyte-free sample exceeds the critical value, leading one to conclude incorrectly that the sample contains a positive amount of the analyte. This type of error is sometimes called a "false positive". An error of the second type occurs if one concludes that a sample does not contain the analyte when it actually does and it is known as a "false negative". In zero-order calibration, this hypothesis test is applied to the confidence intervals of the calibration model to estimate the LOD as proposed by Hubaux and Vos (A. Hubaux, G. Vos, Anal. Chem. 42: 849-855, 1970).

One strategy for estimating multivariate limits of detection is to transform the multivariate model into a univariate one. This strategy has been applied in this thesis in three practical applications:
1. LOD for PARAFAC (Parallel Factor Analysis).
2. LOD for ITTFA (Iterative Target Transformation Factor Analysis).
3. LOD for MCR-ALS (Multivariate Curve Resolution - Alternating Least Squares)

In addition, the thesis includes a theoretical contribution with the proposal of a sample-dependent LOD in the context of multivariate (PLS) and multi-linear (N-PLS) Partial Least Squares.
La Química Analítica es pot dividir en dos tipus d'anàlisis, l'anàlisi quantitativa i l'anàlisi qualitativa. La gran part de la química analítica moderna és quantitativa i fins i tot els govern fan ús d'aquesta ciència per establir regulacions que controlen, per exemple, nivells d'exposició a substàncies tòxiques que poden afectar la salut pública. El concepte de mínima quantitat d'un analit o component que es pot detectar apareix en moltes d'aquestes regulacions, en general com una part de la validació dels mètodes per tal de garantir la qualitat i la validesa dels resultats.

La mínima quantitat d'una substància que pot ser diferenciada de l'absència d'aquesta substància (el que es coneix com un blanc) s'anomena límit de detecció (limit of detection, LOD). En procediments on es treballa amb mesures analítiques que són degudes només a la quantitat d'analit present a la mostra (situació d'ordre zero) el LOD es pot calcular com un múltiple de la mesura del blanc (tradicionalment, 3 vegades la desviació d'aquesta mesura). Tanmateix, l'evolució dels instruments analítics i la complexitat creixent de les dades que generen, porta a situacions en les que el LOD no es pot calcular fiablement d'una forma tan senzilla. Les mesures, els instruments i els models de calibratge es poden classificar en funció del tipus de dades que utilitzen. La Teoria Tensorial s'ha utilitzat en aquesta tesi per fer aquesta classificació amb un llenguatge útil i unificat. Els instruments que generen dades en dues dimensions s'anomenen instruments de segon ordre i un exemple típic és l'espectrofluorímetre d'excitació-emissió, que proporciona un conjunt d'espectres d'emissió obtinguts a diferents longituds d'ona d'excitació.

Els mètodes de calibratge emprats amb cada tipus de dades tenen diferents característiques i complexitat. En aquesta tesi, es fa una revisió dels models de calibratge més habituals d'ordre zero (univariants), de primer ordre (multivariants) i de segon ordre (multilinears). Els mètodes de segon ordre estan tractats amb més detall donat que són els que s'han emprat en les aplicacions pràctiques portades a terme.

Concretament es descriuen:

- PARAFAC (Parallel Factor Analysis)
- ITTFA (Iterative Target Transformation Analysis)
- MCR-ALS (Multivariate Curve Resolution-Alternating Least Squares)
- N-PLS (Multi-linear Partial Least Squares)

Com s'ha avançat al principi, els mètodes analítics s'han de validar. El procés de validació inclou la definició dels límits d'aplicació del procediment analític (des del tipus de mostres o matrius fins l'analit o components d'interès, la tècnica analítica i l'objectiu del procediment). La següent etapa consisteix en identificar i estimar els paràmetres de qualitat (figures of merit, FOM) que s'han de validar per, finalment, documentar els resultats de la validació i mantenir-los mentre sigui aplicable el procediment descrit.

Algunes FOM dels processos químics de mesura són: sensibilitat, selectivitat, límit de detecció, exactitud, precisió, etc. L'objectiu principal d'aquesta tesi és desenvolupar estratègies teòriques i pràctiques per calcular el límit de detecció per problemes analítics complexos. Concretament, està centrat en els mètodes de calibratge que treballen amb dades de segon ordre.

Els mètodes més emprats per definir criteris de detecció estan basats en proves d'hipòtesis i impliquen una elecció entre dues hipòtesis sobre la mostra. La primera hipòtesi és la hipòtesi nul·la: a la mostra no hi ha analit. La segona hipòtesis és la hipòtesis alternativa: a la mostra hi ha analit. En aquest context, hi ha dos tipus d'errors en la decisió. L'error de primer tipus té lloc quan es determina que la mostra conté analit quan no en té i la probabilitat de cometre l'error de primer tipus s'anomena fals positiu. L'error de segon tipus té lloc quan es determina que la mostra no conté analit quan en realitat si en conté i la probabilitat d'aquest error s'anomena fals negatiu. En calibratges d'ordre zero, aquesta prova d'hipòtesi s'aplica als intervals de confiança de la recta de calibratge per calcular el LOD mitjançant les fórmules d'Hubaux i Vos (A. Hubaux, G. Vos, Anal. Chem. 42: 849-855, 1970)

Una estratègia per a calcular límits de detecció quan es treballa amb dades de segon ordre es transformar el model multivariant en un model univariant. Aquesta estratègia s'ha fet servir en la tesi en tres aplicacions diferents::
1. LOD per PARAFAC (Parallel Factor Analysis).
2. LOD per ITTFA (Iterative Target Transformation Factor Analysis).
3. LOD per MCR-ALS (Multivariate Curve Resolution - Alternating Least Squares)

A més, la tesi inclou una contribució teòrica amb la proposta d'un LOD que és específic per cada mostra, en el context del mètode multivariant PLS i del multilinear N-PLS.

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Nqakala, Noniko Civilized. "Construction of an enzyme-free electrochemical sensor based on Ag-Fe2O3/POM/RGO novel nanocomposite for hydrogen peroxide detection". University of the Western Cape, 2018. http://hdl.handle.net/11394/6762.

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>Magister Scientiae - MSc
The motivation to determine H2O2 lies in the fact that this chemical species plays a crucial role in diverse fields of practise such as cosmetic, food, diagnostic, pharmaceutical, clinical and environmental protection industries. Several methods such as chromatography, colorimetry, titrimetry and spectrophotometry have been developed for its detection. However, these methods are known to manifest underlying disadvantages such as high cost, time consuming, instability and complicated immobilization procedures. In this present study an enzyme-less electrochemical sensor based on Ag-Fe2O3/POM/RGO nanocomposite (POM stands for polyoxometalate and RGO stands for reduced graphene oxide) was successfully synthesised via a hydrothermal method and a photochemical reduction method for the detection of hydrogen peroxide (H2O2).

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Oranzie, Marlon. "Electrochemical Aptasensing of B-Type Natriuretic Peptide-A Biomarker for Myocardial Infarction". University of the Western Cape, 2019. http://hdl.handle.net/11394/7707.

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>Magister Scientiae - MSc
infarction (MI) affects many parts of the western world and in South Africa alone it is estimated that MI is responsible for 1 in 6 deaths (17.3%). Traditional diagnostic methods for MI include an electrocardiograms and blood tests. The problem with these diagnostic methods are that they are time consuming, require large sample volumes, expensive equipment and complicated machinery. To achieve early detection of MI the discovery of specific, sensitive and reliable biomarkers are required. Brain natriuretic peptide (BNP) has been identified as a reliable biomarker for MI due to the fact that it has a defined cutoff of 100 pg/ml and it is not susceptible to patient‘s age which could make early detection of BNP complicated. Early detection methods for BNP has been based on immunoradiometric assays but problems associated with immunoradiometric assays are that there is a restricted availability of antigens and incubation of the labeled antibody could take up to two weeks which affects the patients waiting time on results. Electrochemical biosensors are emerging as early detection method for MI because they can be designed to be sensitive, specific to BNP at a low cost. This research study reported for the first the successful fabrication and implementation of highly sensitive mercaptosuccinic acid capped nickel selenide quantum dots (MSA-NiSe2 QDs) aptasensor for the detection of BNP. The poly-dispersed MSA-NiSe2 QDs were synthesized via an inexpensive, simple and reproducible aqueous microwave assisted irradiation method. The prepared MSA-NiSe2 QDs were characterized by Ultraviolet spectroscopy (UV-Vis), X-ray Diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), High Resolution Transmission/Scanning Electron Microscopy (HR TEM/SEM) and Small Angle X-ray Scattering (SAXSpace). The electrochemical properties of the MSA-NiSe2 QDs were investigated by Cylic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS). HR-TEM revealed the formation of small sized MSA-NiSe2 QDs about 4 nm in diameter which was complemented by SAXSpace. UV-Vis studies showed absorption peaks in the ultraviolet region (100-400 nm) confirming the small size of these QDs as well confirming the direct and indirect bandgap of the QDs. XRD confirmed that the QDs are crystalline and belong to the bulk cubic MSA-NiSe2 QDs phase. FTIR studies confirmed the successful capping of MSA on the QDs due to the disappearance of the thiol peak at 2652 cm-1. Electrochemical studies revealed that the MSA-NiSe2 QDs showed good electrochemical properties on screen printed carbon electrodes (SPCE) which allowed them to be used as a mediating platform between the aptamer and SPCE. The successful detection of BNP was achieved by an incubation process between the aptamer drop coated on the MSA-NiSe2 QDs/SPCE surface overnight. The response of the MSA-NiSe2 QDs based aptasensor towards different concentrations of BNP was studied by differential pulse voltammetry (DPV). DPV showed a good linearly with correlation coefficient of R2 = 0.98. DPV also showed a high sensitivity (0.4513 μA/ pg/mL) towards detecting BNP with a detection limit of 11.93 pg/ml. The value of 11.93 pg/ml falls within the negative predictive value range of 10-100 pg/ml for early-stage diagnosis of BNP.

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Mahmood, Rahimi. "Karatärisering av XRF-mätning med 120kV röntgenrör". Thesis, Mittuniversitetet, Institutionen för elektronikkonstruktion, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-42590.

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Syftet med denna undersökning är att utvärdera en XRFmätuppställning som använder högre spänning påröntgenröret än konventionella XRF-instrument. Iutvärderingen uppskattas Limit Of Detection (LOD) påtungmetaller genom att använda XRF-metoden, där dettestades olika filter, vinklar och rörspänning och derasinverkan på provet.Metaller med hög densitet kallas för tungmetaller. Vissatungmetaller är livsnödiga men vissa är skadliga för bådemänniskor och naturen. Några exempel på dessa tungmetallerär kvicksilver, kadmium och bly, vilka är farliga grundämnensom människor kan få i sig via föda.Vid utförande av denna undersökning användes enröntgenkälla (30-120keV) som var kopplad till mjukvaransom skickade fotonenergi och ström. En spektrometer med CdTe-detektor användes för att mäta energin på fotonerna från provet. Detektorn var kopplad till mjukvara där det uppmätt spektra kunde observeras och energitopparnas intensitet kunde avläsas. Topparnas intensitet kan härledas tillprovets samansättning. Sedan uppskattades LOD förproverna. Den teknik som jag har studerat ger möjlighet till bättre mätresultat än konventionella XRFutrustningar. Detta eftersom högre rörspänning gör att K-linjerna, inte bara L-linjerna, för tungmetaller kan avläsas

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Ngwanya, Olwethu. "Molecularly imprinted polymers for detection of volatile organics associated with fuel combustion". University of the Western Cape, 2018. http://hdl.handle.net/11394/6363.

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Magister Scientiae - MSc (Chemistry)
Pollutants such as polycyclic aromatic hydrocarbons (PAHs) are known for their toxic effects which may lead to the cause of degenerative diseases in both humans and animals. PAHs are widespread in the environment, and may be found in water, food, automotive industry and petrochemical industries to name but a few sources. Literature reports have highlighted industrial workplace exposure to PAHs as a leading cause for development of cancer in workers. Particularly, workers in the petrochemical industry are adversely affected and the incidence of skin and lung cancer in this population group is high. The United States of America in its guidelines developed by environmental protection agency (EPA) has identified 18 PAHs as priority pollutants. Among these are anthracene, benzo[a]pyrene and pyrene which have been selected as the focal point of this study due to their significance in the petrochemical industry. Due to the carcinogenic and mutagenic properties reported in literature for certain PAHs, there have been monitoring procedures taken in most countries around the world. The commonly used analytical methods for the detection of PAHs from industrial samples are high performance liquid chromatography (HPLC) coupled to fluorescence detection, membrane filtration, ozonation and reverse osmosis. Analysis of PAHs from the petrochemical industry is typically performed by HPLC method as well as sono-degredation in the presence of oxygen and hydrogen peroxide.

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Guo, Jing. "MULTI-MODE SELF-REFERENCING SURFACE PLASMON RESONANCE SENSORS". UKnowledge, 2013. http://uknowledge.uky.edu/ece_etds/13.

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Surface-plasmon-resonance (SPR) sensors are widely used in biological, chemical, medical, and environmental sensing. This dissertation describes the design and development of dual-mode, self-referencing SPR sensors supporting two surface-plasmon modes (long- and short-range) which can differentiate surface binding interactions from bulk index changes at a single sensing location. Dual-mode SPR sensors have been optimized for surface limit of detection (LOD). In a wavelength interrogated optical setup, both surface plasmons are simultaneously excited at the same location and incident angle but at different wavelengths. To improve the sensor performance, a new approach to dual-mode SPR sensing is presented that offers improved differentiation between surface and bulk effects. By using an angular interrogation, both surface plasmons are simultaneously excited at the same location and wavelength but at different angles. Angular interrogation offers at least a factor of 3.6 improvement in surface and bulk cross-sensitivity compared to wavelength-interrogated dual-mode SPR sensors. Multi-mode SPR sensors supporting at least three surface-plasmon modes can differentiate a target surface effect from interfering surface effects and bulk index changes. This dissertation describes a tri-mode SPR sensor which supports three surface plasmon resonance modes at one single sensing position, where each mode is excited at a different wavelength. The tri-mode SPR sensor can successfully differentiate specific binding from the non-specific binding and bulk index changes.

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Feleni, Usisipho. "Quantum dots-amplified electrochemical cytochrome P450 phenotype sensor for tamoxifen, a breast cancer drug". University of the Western Cape, 2017. http://hdl.handle.net/11394/5505.

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Philosophiae Doctor - PhD
Breast cancer is regarded as the most common cancer in South Africa and its rate of occurrence is increasing. About one in every 31 South African women are at the risk of developing breast cancer and early diagnosis and treatment guarantee 90% survival rate. Tamoxifen is the drugs of choice for the treatment of all stages of breast cancer. The drug binds with estrogen receptor (ER) to minimize the transcription of estrogen dependent genes. However, nearly 50% of ER-positive breast cancer patients either become resistant or fail to respond to tamoxifen resulting in a serious clinical challenge in breast cancer management. The Grand Health Challenges of South Africa includes the development of cost effective diagnostic systems suitable for early detection of diseases and drug resistivity for timely invention and better patient management.
2020-08-31

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Yavrucuk, Ilkay. "Adaptive limit margin detection and limit avoidance". Diss., Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/12354.

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Horn, Joe. "Flight envelope limit detection and avoidance". Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/12435.

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Libri sul tema "Limit of Detection (LOD)"

Lehrasab, Nadeem. A generic fault detection and isolation approach for single-throw mechanical equipment. Birmingham: University of Birmingham, 1999.

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Manraj, A. Shakoor. The law on speeding and speed detection devices. 3^a ed. Markham, Ont: LexisNexis, 2007.

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Springs, David W. How to outfox the bears: Beating the radar speed trap. Osceola, Wis., USA: Motorbooks International, 1987.

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National Council on Radiation Protection and Measurements. Radiological health protection issues associated with use of active detection technology systems for detection of radioactive threat materials. Bethesda, Md: National Council on Radiation Protection and Measurements, 2011.

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The complete book on speed enforcement: A practical guide to understanding speed enforcement concepts and devices. Springfield, Ill: Charles C. Thomas, 2012.

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New Jersey. Legislature. Senate. Committee on Law, Public Safety, and Defense. Public hearing before Senate Law, Public Safety, and Defense Committee: To elicit testimony for discussion on the role of local governmental and law enforcement officials on monitoring the transportation of hazardous materials, receiving regular and timely notification when hazardous materials are transported through any municipality and effectively enforcing current laws regulating the transportation of hazardous materials in this state : May 4, 1988, Paramus Borough Hall, Paramus, New Jersey. Trenton, N.J: The Committee, 1988.

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New Jersey. Legislature. Senate. Committee on Law, Public Safety, and Defense. Public hearing before Senate Law, Public Safety, and Defense Committee: Senate bill 2733 (reduces the blood alcohol content level for driving a commercial motor vehicle under the influence of alcohol to 0.04%), and Senate bill 2741 (prohibits the use or possession of radar detectors in commercial motor vehicles) : February 11, 1987, Council Chambers, Burlington Township Municipal Building, Burlington Township, New Jersey. Trenton, N.J: The Committee, 1987.

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New, Jersey Legislature Senate Committee on Law Public Safety and Defense, e Jersey Legislature Senate Committee on Law Public Safety and Defense New. Public hearing before Senate Law, Public Safety and Defense Committee: A discussion of issues concerning the restructuring of motor vehicle license plates and the misuse of drivers' licenses : July 21, 1987, New Jersey Institute of Technology, Newark, New Jersey. Trenton, N.J: The Committee, 1987.

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New Jersey. Legislature. Senate. Committee on Law, Public Safety, and Defense. Public hearing before Senate Law, Public Safety, and Defense Committee: Motor vehicle inspections : February 4, 1991, Room 407, State House Annex, Trenton, New Jersey. Trenton, N.J: The Committee, 1991.

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New, Jersey Legislature Senate Committee on Law Public Safety and Defense. Public hearing before Senate Law, Public Safety, and Defense Committee: Continuation of February 25, 1991 hearing to receive testimony from individuals and organizations on the recently announced plans to change the standards and procedures for the motor vehicle inspection system administered by the Division of Motor Vehicles (see previous transcript dated 2/25/91) : March 11, 1991, Room 407, State House Annex, Trenton, New Jersey. Trenton, N.J: The Committee, 1991.

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Capitoli di libri sul tema "Limit of Detection (LOD)"

Eremenko, Arkadiy, Il'ya Kurochkin e Nataliya Nechaeva. "Bioanalytical systems based on cholinesterases for detection of organophosphates". In ORGANOPHOSPHORUS NEUROTOXINS, 205–18. ru: Publishing Center RIOR, 2020. http://dx.doi.org/10.29039/32_205-218.

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Various types of electrochemical sensors based on the inhibition of butyrylcholinesterase (BChE) have been presented for the analysis of organophosphates (OPC). A special design of thick film sensors and electrochemical detector for cholinesterases assay and their inhibitors in aqueous samples has been developed. For this assay, thiol sensitive sensors based on screen printed graphite electrode modified with nanoparticles of manganese dioxide were used. High sensitivity of manganese dioxide modified thick film sensors towards thiocholine and therefore low detection limit of BChE (1 pM) enabled their use for subnanomolar detection of an organophosphate pesticide diazinon, and other irreversible inhibitors of BChE. This work also presents modern innovative approach for the analysis of BChE by Raman spectroscopy. New SERS-substrates based on silver paste for sensitive quantification of BChE activity were obtained, characterized and applied to thiocholine detection, with LOD (TCh) being 260 nM. Real samples of human plasma were analyzed; a good correlation between spectrophotometric detection and Raman detection was shown. The developed technique is inexpensive and easy-to-use and has promising potential for analysis of OPC.

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Eremenko, Arkadiy, Il'ya Kurochkin e Nataliya Nechaeva. "Bioanalytical systems based on cholinesterases for detection of organophosphates". In Organophosphorous Neurotoxins, 0. ru: Publishing Center RIOR, 2020. http://dx.doi.org/10.29039/chapter_5e4132b6096d14.18045940.

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Gooch, Jan W. "Detection Limit". In Encyclopedic Dictionary of Polymers, 202. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_3458.

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Bzik, Thomas J. "Detecting the Detection Limit". In Detection Limits in Air Quality and Environmental Measurements, 1–15. 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959: ASTM International, 2019. http://dx.doi.org/10.1520/stp161820180117.

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Isermann, Rolf. "Fault detection with limit checking". In Fault-Diagnosis Systems, 95–110. Berlin, Heidelberg: Springer Berlin Heidelberg, 2006. http://dx.doi.org/10.1007/3-540-30368-5_7.

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Johnson, James E., e Janet A. Johnson. "Radioactivity Analyses and Detection Limit Problems". In ACS Symposium Series, 266–74. Washington, DC: American Chemical Society, 1987. http://dx.doi.org/10.1021/bk-1988-0361.ch014.

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Zamborlini, Veruska, Rinke Hoekstra, Marcos da Silveira, Cedric Pruski, Annette ten Teije e Frank van Harmelen. "Generalizing the Detection of Clinical Guideline Interactions Enhanced with LOD". In Biomedical Engineering Systems and Technologies, 360–86. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-54717-6_20.

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Krivanek, Ondrej L., Wu Zhou, Matthew F. Chisholm, Juan Carlos Idrobo, Tracy C. Lovejoy, Quentin M. Ramasse e Niklas Dellby. "Gentle STEM of Single Atoms: Low keV Imaging and Analysis at Ultimate Detection Limits". In Low Voltage Electron Microscopy, 119–61. Chichester, UK: John Wiley & Sons, Ltd, 2012. http://dx.doi.org/10.1002/9781118498514.ch6.

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Owens, K. G., C. F. Bauer e C. L. Grant. "Effects of Analytical Calibration Models on Detection Limit Estimates". In ACS Symposium Series, 194–207. Washington, DC: American Chemical Society, 1987. http://dx.doi.org/10.1021/bk-1988-0361.ch010.

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Zhu, Lei, Chun-Sheng Yang e Jeng-Shyang Pan. "Detection and Recognition of Speed Limit Sign from Video". In Intelligent Information and Database Systems, 760–69. Berlin, Heidelberg: Springer Berlin Heidelberg, 2016. http://dx.doi.org/10.1007/978-3-662-49381-6_73.

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Atti di convegni sul tema "Limit of Detection (LOD)"

Koc, Hilal, Gulsah Kadihasanoglu, M. Dilruba Geyikoglu, M. Emin Dertli, Bulent Cavusoglu, I. Yucel Ozbek, E. Argun Oral et al. "Improving the limit of detection (LOD) of microsensor used in detection of brain diseases via wavelet filter". In 2015 23th Signal Processing and Communications Applications Conference (SIU). IEEE, 2015. http://dx.doi.org/10.1109/siu.2015.7130174.

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Gravel, Jean-François, Martin Allard, François Babin, François Chateauneuf e Eric Bergeron. "Oil Pipeline Standoff Leak Detection: A Novel Approach for Airborne Remote Detection of Small Leaks". In 2016 11th International Pipeline Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/ipc2016-64704.

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While natural gas pipelines already benefit from airborne, remote detection of leaks [1, 2], oil pipeline leak detection has been for a long time reliant on SCADA systems limited in their capability to detect very small leaks, and/or visual inspection of the right of way (line flyers, pipeline employees or members of the public). This paper presents a novel and complementary way of detecting small leaks (i.e. sensitivity of 0.1 L/minute, 1 barrel/day) of oil (crude or refined products) using an optical detection system mounted on an airborne platform (UAV, plane or helicopter). The scope of this paper is based on the requirements provided by TransCanada, namely sensitivity (herein referred as LOD — Limit of Detection) and accuracy (herein referred as spatial resolution) as similar to their description in API 1130, while the topic of reliability is addressed in our noted concerns on the false alarms that may be generated in Infrared-DiAL based systems due to soil reflectivity. Robustness, as described in API 1130, was out of scope. Keeping in mind the requirement of airborne operation, three different approaches for the detection of leaks along long pipeline ROWs were studied. Infrared Differential Absorption lidar (IR-DiAL), UltraViolet Raman lidar (UV-Raman lidar) and UltraViolet Laser-Induced Fluorescence lidar (UV-LIF lidar) have been tested in realistic conditions. In the first round of tests, laboratory spectral measurements of vapors in a closed cell were performed. In the second round of tests, the breadboards were placed in a mobile laboratory and the light beams aimed at a large open at 40 to 50 meters and reflected off a sand target. Finally, the mobile laboratory with the breadboards was installed at ∼40 meters from a leak simulator. The leak simulator was made by using a large sand container in which petroleum products were leaked. Intermediate scale leak simulator tests showed that it is clearly a challenge to correlate a measured concentration to an actual leak size. Tests have also shown that there is a strong concentration gradient in the air above a leak. This indicates that a better overall detection performance should be obtained with a measurement using the air next to the ground, and that it is feasible to detect a leak of less than 1 barrel/day. UV-Raman tests performed in the outdoors suggested a Limit Of Detection (LOD) of the system below 1 500 ppm-m when detecting all hydrocarbons. Because of the hardware that would be needed to lower this detection limit, results suggest abandoning the Raman technique for remote leak detection from an airborne platform. IR-DiAL showed the best sensitivity for the detection of hydrocarbons (< 1 ppm-m of LOD). However the effective LOD will be reduced because of the soil spectral reflectance variations that may lead to a high false alarm rate for concentrations of hydrocarbons lower than 235 ppm-m. The UV-absorption approach was also briefly tested, suggesting a LOD for benzene of between 1.5 and 2.5 ppm-m. The UV absorption of benzene is not affected by ground spectral reflectance variations. This is an approach that will be investigated further.

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Akard, Michael, Kazuya Tsurumi, Karl Oestergaard e Kaori Inoue. "Why the Limit of Detection (LOD) Value is Not an Appropriate Specification for Automotive Emissions Analyzers". In SAE Powertrain & Fluid Systems Conference & Exhibition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2002. http://dx.doi.org/10.4271/2002-01-2711.

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Zhao, Chen, Guowei Zhong, Da-Eun Kim, Jinxia Liu e Xinyu Liu. "A Portable Analytical System for Colorimetric Detection of Metal Ions in Water". In ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-38994.

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Heavy metal ions released into various water environments have severe impact on both human beings and aqueous environments, and excess amount of lead and aluminum ions pose high risks to human health and could cause life-threatened diseases. The existence of metal ions in drinking water contributes most to the daily intake by humans, and thus it urges to develop a rapid, low-cost and sensitive method for detection of heavy metal ions. In this research, we develop a portable analytical system for metal ion detection in water by combining a powerful gold nanoparticle (AuNP) based colorimetric method with lab-on-a-chip technology. We utilize single-step assays involving surface functionalized AuNPs for colorimetric detection of lead (Pb2+) and aluminum (Al3+) ions in water with low limit of detection (LOD) and high sensitivity. We demonstrate that this portable system provides LODs of 30 ppb for Pb2+ and 89 ppb for Al3+, both comparable to bench-top analytical spectrometers. The system permits metal ion detections in a more economical and convenient fashion, and is particularly useful for water quality monitoring in remote and/or resource-poor settings.

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Jofre, M., J. M. Perez, P. Martinez, Z. Moubarak, C. Hurth, MA Yanez, V. Catalan, A. Parker, M. Veldhuis e V. Prunei. "CMOS-based Image Cytometry for Detection of Phytoplankton in Ballast Water". In IMarEST Ballast Water Technology Conference. IMarEST, 2017. http://dx.doi.org/10.24868/bwtc6.2017.005.

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An image cytometer (CYT) for the analysis of phytoplankton in fresh and marine water environments is introduced. A linear quantification of the number of cells over several orders of magnitude of concentrations was observed using cultures of Tetraselmis and Nannochloropsis measured by autofluorescence of the chlorophyll in a laboratory environment. The functionality of the system outside the laboratory was analysed by phytoplankton quantification of samples taken from marine water environment (Dutch Wadden Sea, The Netherlands) and fresh water environment (Lake Ijssel, The Netherlands). The CYT was also employed to study the effects of two ballast water treatment systems (BWTS), based on chlorine electrolysis and UV sterilisation by determining the vitality of the phytoplankton. In order to ensure the detection limit, a large volume (1l) of samples was collected and concentrated to 3 ml using CelltrapTM filters. The results were compared to benchmarked flow cytometer and PAM Fluorometry at Marine Eco-Analytics (MEA-NL). The image cytometer reached a 10 cells/ml limit of detection (LoD) with an accuracy between 0.7 and 0.5 log, and a correlation of 88.29% in quantification and 96.21% in vitality, when compared to benchmarked monitoring techniques.

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Liu, Fan, Pawan K. C., Ge Zhang e Jiang Zhe. "Target Cell Detection via Microfluidic Magnetic Beads Assay". In ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-65088.

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We present a novel cell detection device based on a magnetic bead cell assay and microfluidic Coulter counting technology. The device can detect specific target cells ratios, as well as cells size distribution and concentrations. The device consists of two identical micro Coulter counters separated by a fluid chamber where an external magnetic field is applied. Target cells conjugated with magnetic beads are retarded by the magnetic field; transit time of a target cell passing through the second counter is longer than that through the first counter. In comparison, a non-target cell transit through two counters with nearly the same time. We demonstrated the transit time delay increased approximately linearly with the increasing target cell concentration. The limit of detection (LOD) of the assay was estimated to be 5.6% in terms of target cell ratio.

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LU, YABIN, Kara Ooi, Keegan Shi e Emily Chan. "Abstract 4272: Improving measurement of assay variation and Limit of Detection (LOD) of ctDNA assay by using validation samples contrived with DNA-free human plasma". In Proceedings: AACR Annual Meeting 2020; April 27-28, 2020 and June 22-24, 2020; Philadelphia, PA. American Association for Cancer Research, 2020. http://dx.doi.org/10.1158/1538-7445.am2020-4272.

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Burge, Scott R. "Automated Analysis of Trichloroethene and Chloroform". In ASME 2003 9th International Conference on Radioactive Waste Management and Environmental Remediation. ASMEDC, 2003. http://dx.doi.org/10.1115/icem2003-4648.

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Chloroform and trichloroethene (TCE) are two organic contaminants commonly encountered in ground water. TCE, formerly a common cleaning solvent, is usually associated with contaminated aquifers. Chloroform is usually associated with the chlorination of municipal water. The remediation level for TCE in aquifers is typically 5 ppb, therefore, the analytical method employed for monitoring these analytes must be capable of detecting and quantifying the analytes in the low ppb concentration range. The most common analytical methodology for the determination of TCE or chloroform in water is a purge and trap technique for sample introduction into a gas chromatographic system equipped with electroconductivity or mass spectroscopy detector. The instrumentation has a method limit of detection (LOD) of less than 0.5 ppb for TCE and chloroform, however, the expense, size and complexity of the gas chromatographic techniques limit its use outside the laboratory environment. An alternative to the gas chromatographic method for the analysis of select volatile chlorinated compounds in the low concentration range is an analytical instrument based on a halocarbon-specific optrode. The principle of detection is a quantitative, irreversible chemical reaction (modified Fujiwara reaction) that forms visible light-absorbing products. The operational basis of the optrode is the measure of the time history of the development of the colored (red) product formed by the reaction of the target analytes. The optrode has the selectivity and sensitivity for monitoring TCE and chloroform at the low ppb concentration range in the presence of other volatile chlorinated contaminants. The low-power requirements and simplicity of design make it a good choice for remote operations. This paper presents the analytical results (January 2002, to December 2002) of a panel-mounted instrument used to monitor the influent and effluent water of a TCE treatment facility located in Scottsdale, Arizona, and the analytical results of a well-mounted instrument used to monitor ground water (May 2002, to August 2002) at Edwards Air Force Base, California.

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Chuang, Han-Sheng, Hsiao-Neng Lin e Hu-Yao Ku. "Development of a Bead-Based Optoelectrokinetic Immunosensing Technique for Detection of Low-Abundance Analytes". In ASME 2017 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/fedsm2017-69146.

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Bead-based immunosensing has been growing as a promising technology in the point-of-care diagnostics because of great flexibility. For dilute samples, functionalized particles can be used to collect dispersed analytes and act as carriers for particle manipulation. To carry out rapid and selective diagnosis, a bead-based optoelectrokinetic immunosensing technique was developed herein to detect biomarkers, lipocalin 1 (LCN1) and TNF-α, for diabetic retinopathy (DR). The measurement was made in a sample droplet sandwiched between two parallel electrodes. With an electric field and a focused laser beam simultaneously applying on the microchip, the immunocomplexes in the droplet were further concentrated within the region of irradiation to enhance the fluorescent signal. The optoelectrokinetic platform, termed rapid electrokinetic patterning (REP), is excellent in dynamic and programmable particle manipulation. Therefore, the detection could be complete in roughly 10 s. With an appropriate frequency modulation, the two DR biomarkers were detected at a time. The limit of detection (LOD) of the REP-enabled measurement reached as low as 100 pg/mL. The combined use of bead-based immunoassays and the optoelectrokinetic platform therefore provides an insightful measure to the early diagnosis of diseases.

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Bull, Richard K., e Ian Adsley. "Bayesian Statistics Applied to the Activities of Waste Drums". In ASME 2011 14th International Conference on Environmental Remediation and Radioactive Waste Management. ASMEDC, 2011. http://dx.doi.org/10.1115/icem2011-59081.

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Gamma spectrometry is widely used to determine the radioactive content of waste drums. However, the results of such surveys often result in large numbers of limit-of-detection (LOD) results. In a previous paper it was shown how simple statistical methods could be used to make estimates of the mean activity of a set of waste drums even when the individual measurements were dominated by limit-of-detection results. In that approach it was necessary to make assumptions about the statistical distribution (taken to be lognormal) of the activities and the geometric standard deviations of the distributions. In this paper a development of the method is presented which uses two statistical methods — Bayes’ Theorem and marginalization. These allow the probability distribution of the mean activity of the waste drums to be calculated, whilst the number of assumptions is reduced to just one, namely the form of the statistical distribution. The mathematical details are described in the paper and the application to a set of U235-in-drum measurements is presented.

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Rapporti di organizzazioni sul tema "Limit of Detection (LOD)"

WESTSIK, G. A. Lower Limit of Detection (LLD) Determination for PFP Residues Segmented Gamma Scan Assay System (SGSAS). Office of Scientific and Technical Information (OSTI), giugno 2002. http://dx.doi.org/10.2172/808108.

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Tracy, L., e S. Nasarabadi. Spore Disruption Analysis and Detection Limit Determination at Low Volume Amplifications (2-10 uL) of Bacillus globigii Using eTags. Office of Scientific and Technical Information (OSTI), agosto 2005. http://dx.doi.org/10.2172/919212.

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Piepel, Gregory F., Janine R. Hutchison, Brooke L. Deatherage Kaiser, Brett G. Amidan, Michael A. Sydor e Christopher A. Barrett. Recovery Efficiency, False Negative Rate, and Limit of Detection Performance of a Validated Macrofoam-Swab Sampling Method with Low Surface Concentrations of Two Bacillus anthracis Surrogates. Office of Scientific and Technical Information (OSTI), marzo 2015. http://dx.doi.org/10.2172/1179143.

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Piepel, Gregory F., Janine R. Hutchison, Brooke L. D. Kaiser, Brett G. Amidan, Michael A. Sydor e Christopher A. Barrett. Recovery Efficiency, False Negative Rate, and Limit of Detection Performance of a Validated Macrofoam-Swab Sampling Method with Low Surface Concentrations of Two Bacillus anthracis Surrogates. Office of Scientific and Technical Information (OSTI), giugno 2016. http://dx.doi.org/10.2172/1406835.

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Strobel, R., e J. Kury. Nitromethane K-9 Detection Limit. Office of Scientific and Technical Information (OSTI), agosto 2003. http://dx.doi.org/10.2172/15007320.

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Ford, S., e J. Sweeney. Low-frequency Electromagnetic Detection Limits of Underground Nuclear Explosions. Office of Scientific and Technical Information (OSTI), settembre 2020. http://dx.doi.org/10.2172/1670539.

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WHITE, THOMASL. Reducing the Detection Limit for Tetraphenylborate in Tank 50H Waste. Office of Scientific and Technical Information (OSTI), luglio 2004. http://dx.doi.org/10.2172/826189.

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Chung, C. F. Statistical treatment of geochemical data with observations below the detection limit. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1985. http://dx.doi.org/10.4095/120239.

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De Lucia, Jr, e Frank C. Producing Known Quantities Of RDX for LIBS Limit of Detection Study. Fort Belvoir, VA: Defense Technical Information Center, maggio 2012. http://dx.doi.org/10.21236/ada562865.

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Crouch, Rebecca, Jared Smith, Bobbi Stromer, Christian Hubley, Samuel Beal, Guilherme Lotufo, Afrachanna Butler et al. Methods for simultaneous determination of legacy and insensitive munition (IM) constituents in aqueous, soil/sediment, and tissue matrices. Engineer Research and Development Center (U.S.), agosto 2021. http://dx.doi.org/10.21079/11681/41720.

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Abstract (sommario):

Currently, no standard method exists for analyzing insensitive munition (IM) compounds in environmental matrices, with or without concurrent legacy munition compounds, resulting in potentially inaccurate determinations. The primary objective of this work was to develop new methods of extraction, pre-concentration, and analytical separation/quantitation of 17 legacy munition compounds along with several additional IM compounds, IM breakdown products, and other munition compounds that are not currently included in U.S. Environmental Protection Agency (EPA) Method 8330B. Analytical methods were developed to enable sensitive, simultaneous detection and quantitation of the 24 IM and legacy compounds, including two orthogonal high-performance liquid chromatography (HPLC) column separations with either ultraviolet (UV) or mass spectrometric (MS) detection. Procedures were developed for simultaneous extraction of all 24 analytes and two surrogates (1,2-dinitrobenzene, 1,2-DNB; o-NBA) from high- and low-level aqueous matrices and solid matrices, using acidification, solid phase extraction (SPE), or solvent extraction (SE), respectively. The majority of compounds were recovered from four tissue types within current limits for solids, with generally low recovery only for Tetryl (from 4 to 62%). A preparatory chromatographic interference removal procedure was adapted for tissue extracts, as various analytical interferences were observed for all studied tissue types.

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