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Journal articles on the topic 'Titrations'

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Published: 4 June 2021

Last updated: 1 February 2022

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1

FERNANDEZ-MAESTRE, Roberto. "THE IMPORTANCE OF TEACHING TITRATION CURVES IN ANALYTICAL CHEMISTRY." Periódico Tchê Química 17, no. 34 (March 20, 2020): 213–19. http://dx.doi.org/10.52571/ptq.v17.n34.2020.230_p34_pgs_213_219.pdf.

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Titration curves are an essential subject of an Analytical Chemistry course. The main objective of calculating titration curves is the selection of an indicator for such titrations. The calculation of titration errors is imperative because they establish if a given indicator can be used for a given titration. This study reviews the available literature on titration curves and calculating their errors. Its purpose is to draw attention to the importance of undergraduate chemistry students having competencies to determine the titration errors rather than skills to build titration curves as the ultimate purpose of these curves is to determine the failure committed when using a given indicator to assess their endpoints. It is shown that the pH and potential calculation at the equivalence point in acid-base and redox titrations, respectively, are not required to choose the titration indicator, one that yields an acceptable error according to the type of application needed. Methods to calculate these errors in the four main types of titrations are presented; those for complexometric and precipitation titrations are simpler than in the literature. Here, it is also demonstrated that calculating points immediately after and before the curve inflection are more critical for this selection in these two types of titrations. Also, it is deducted that complexometric and precipitation curves are not required to select indicators for these titrations. These demonstrations are essential because analytical chemistry teachers may disregard teaching important topics by spending time calculating unnecessary titration curves (complexometric and precipitation titrations) or additional points of titration curves (redox and acid-base titrations) when the calculation of titration errors of these reactions is more critical. Most analytical chemistry textbooks neglect this topic. Undergraduate chemistry programs should focus more on calculating titration errors than on the construction of titration curves.

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2

Gonzalez, G. G., A. M. Jimenez, and A. G. Asuero. "Titration errors in acid-base titrations." Microchemical Journal 41, no. 1 (February 1990): 113–20. http://dx.doi.org/10.1016/0026-265x(90)90103-c.

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3

Gibson, Graham, Alexei A. Neverov, and R. S. Brown. "Potentiometric titration of metal ions in methanol." Canadian Journal of Chemistry 81, no. 6 (June 1, 2003): 495–504. http://dx.doi.org/10.1139/v03-035.

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The potentiometric titrations of nine lanthanideIII triflates, ZnII and CuII triflate, and the NiII, CoII, MgII, and TiIV perchlorates were obtained in methanol to determine the titration constants (defined as the sspH at which the [OCH3]/[Mx+]t ratios are 0.5 and 1.5) as well as the apparent sspKa values for deprotonation of the metal-bound solvent molecules. The titrations were performed under various conditions with and without added salts as electrolytes, and the variations in the titration constants are discussed. In selected cases (La3+, Zn2+) the titration profiles were analyzed using a complex fitting program to obtain information about the species present in solution.Key words: potentiometric titration, methanol, sspH, metal ion, lanthanides, apparent sspKa.

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4

Besenhard, J. O., H. P. Gansmann, and H. Meyer. "Bestimmung von Oberflächenoxiden auf Rußen durch potentiometrische Direkttitration in nichtwäßrigen Lösungsmitteln / Determination of Surface Oxides on Carbon Blacks by Direct Potentiometric Titration in Non-Aqueous Solvents." Zeitschrift für Naturforschung B 45, no. 6 (June 1, 1990): 857–63. http://dx.doi.org/10.1515/znb-1990-0617.

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An attempt is made to quantitatively determine acidic and basic surface oxides on carbon blacks and also to monitor their acid and base strength distribution by direct potentiometric titrations in non-aqueous media.In contrast to direct titration procedures proposed so far, our method allows to distinguish clearly between several types of acidic surface oxides of different acid strength. This is mainly achieved by improvements of the non-aqueous titration media. The total contents of weakly and strongly acidic and also of basic oxides determined by this very fast method is comparable to results obtained by slow and laborious indirect titrations.

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5

Ramette, Richard W. "Gravimetric Titrations: In Support of Weight Titration Techniques." Journal of Chemical Education 81, no. 12 (December 2004): 1715. http://dx.doi.org/10.1021/ed081p1715.2.

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6

Morák, M., and Ústi nad Labem. "Titration von Alkylammoniumsalzen / Titrations of Alkyl Ammonium Salts." Tenside Surfactants Detergents 26, no. 3 (May 1, 1989): 215–21. http://dx.doi.org/10.1515/tsd-1989-260316.

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7

Fuhrmann, B., and U. Spohn. "A PC-based titrator for flow gradient titrations." Journal of Automatic Chemistry 15, no. 6 (1993): 209–16. http://dx.doi.org/10.1155/s1463924693000276.

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This paper describes a PC (personal computer) based titrator which was developed for gradient flow titrations. Concentration gradients were generated electrolytically or volumetrically in small tubes. Complete titration curves can be recorded on-line and evaluated automatically. The titrator can be used with all liquid flow detectors with low axial dispersion. The titrator was evaluated for the titration of thiosulphate with electrogenerated triiodide and for the titration of ammonia with electrogenerated hypobromite after continuous gas dialytic separation of ammonia from the sample solution.

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8

Bodiroga, Milanka, and Jasminka Ognjanovic. "Determination of peracetic acid and hydrogen peroxide in the mixture." Vojnosanitetski pregled 59, no. 3 (2002): 277–79. http://dx.doi.org/10.2298/vsp0203277b.

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Iodometric and permanganometric titrations were used for determination of peracetic acid and hydrogen peroxide (H2O2) in the mixture. Two procedures were described and compared. Titrations could be done in only one vessel, in the same reaction mixture, when iodometric titration of peracetic acid was continued after the permanganometric titration of H2O2, (procedure A). Peracetic acid and H2O2, as oxidizing agents, reacted with potassium iodide in an acid medium, evolving iodine. This reaction was used for the quantitative iodometric determination of total peroxide in procedure B. H2O2 reacted with potassium permanganate in acid medium, but peracetic acid did not react under the same conditions. That made possible the selective permanganometric determination of H2O2 in the presence of peracetic acid. The procedure B was performed in two titration vessels (KV=3.4% for peracetic acid, 0.6% for H2O2). The procedure A for iodometric determination of peracetic acid in one titration vessel after permanganometric titration of H2O2 was recommended (KV=2,5% for peracetic acid, 0,45% for H2O2).

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9

Ikeshoji, Tamio. "Titrations by Temperature Difference Electrode: Entropy Titrations." Bulletin of the Chemical Society of Japan 59, no. 6 (June 1986): 2023–25. http://dx.doi.org/10.1246/bcsj.59.2023.

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10

Bond, T. Christopher, Jaime Rubin, Steven X. Wang, and Alex Yang. "More Frequent Hemoglobin Measurements and More Frequent Epoetin Alfa Titrations Are Both Associated with Increased Epoetin Alfa Dose but Not More Time in Target Hemoglobin Range,." Blood 118, no. 21 (November 18, 2011): 4194. http://dx.doi.org/10.1182/blood.v118.21.4194.4194.

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Abstract Abstract 4194 For the past 20 years, management of hemoglobin (Hb) level via erythropoiesis-stimulating agents (ESAs), such as epoetin alfa (EPO) has been the norm in the care of end-stage renal disease (ESRD) patients. Recently, questions about patient safety and new economic bundling rules have brought renewed focus on appropriate Hb targets and how they relate to the use of EPO. Important issues related to Hb control are the frequency of Hb measurements, Hb value, the frequency of changes in EPO dose (titrations), and total EPO dose. Current practice aims to achieve greater control of Hb by more frequent measurement and finer EPO dose titrations. No studies have definitively shown that levels of titration and measurement frequency lead to better clinical outcomes or more efficient use of EPO. One large retrospective analysis found increasing Hb measurements and EPO dose titration frequency decreased patient variability around the facility-level Hb mean (Khan et al, 2011). However, a second study found that frequent titrations have been shown to be the most important driver of Hb cycling—potentially dangerous large fluctuations in Hb levels (Fishbane and Berns, 2005). The issue remains controversial. We conducted a retrospective database analysis in order to quantify the frequency of Hb dose titrations and measurements, and to evaluate their relationship to ESA dose and the ability to keep patients within a Hb range of 10–12 g/dL. Data from prevalent (≥ 120 days), adult (>18 years old) hemodialysis patients dialyzing at DaVita dialysis clinics ≥ 3 times per week between January 1, 2009 and December 31, 2010 were included. For every session, patients' stable dosing periods were defined as any series of at least 3 doses during which the dose did not change more than 10% from first dose in the series. Dose holds were defined as ≥ 3 consecutive sessions with 0 EPO dose. An EPO dose of 0 lasting <3 consecutive sessions was ignored when identifying stable periods and holds. Doses not categorized as part of a stable period or a dose hold were considered transition periods. A dose titration was defined as a difference of > 10% between any of the following: the mean dose of 2 consecutive stable periods; the mean dose of stable period and next/previous dose in transition period; and 2 consecutive doses within a transition period. Transitions involving a dose hold were counted as 1 titration if the patient then returned to a dose within 10% of the mean of the prior period; or 2 titrations otherwise. Similar rules were developed for the minority of patients who received EPO once or twice per week. Correlations among measures (titrations/patient-month and Hb measurements/patient-month with mean monthly EPO dose and time with Hb in range) were assessed using Pearson product-moment correlation and linear regression (adjusted for racial composition, percentage of dialysis vascular access types, percentage with comorbidities, and mean age, vintage, and BMI) at the physician and the facility levels. Time in range was defined as total patient time in range/total patient-time. Facility level analyses were weighted by facility load (minimum of 300 patient-months) and are reported here. Information from 81,464 patients at 1,336 facilities was assessed. The mean number of titrations was 13.6 ± 2.83 (mean ± SD) per patient per year and the mean number of Hb measurements was 36.3 ± 8.24 per patient per year. The mean percent of patient-time in range among these facilities was 57.1% ± 5.8%. At the facility level, after adjustment for case mix factors (mean age, vintage, and BMI at facility, access types, and racial composition) the annual number of dose titrations per patient and Hb measurements per patient were not associated with the percent of patient-months within a 10–12 g/dL Hb range (p=0.12 and p=0.47; respectively). An analysis of ESA utilization showed that an increase of 1 titration per patient at the facility level was associated with an extra 18,000 U (p<0.001) per patient. In this retrospective study of >80,000 US dialysis patients over 2 years, neither increased Hb measurements nor increased EPO titrations were associated with improving patient-time in Hb range. However, increased EPO titrations were associated with significantly increased EPO utilization. Although these associations do not demonstrate causality (or the direction of potential causality), they do underscore the need to assess titration practices. Disclosures: Bond: DaVita Clinical Research: Employment; Affymax Inc: Research presented in this study was paid for by Affymax. Rubin:DaVita Clinical Research: Employment; Affymax: The research presented in this abstract was paid for by Affymax. Wang:DaVita Clinical Research: Employment; Affymax: The research presented in this abstract was paid for by Affymax. Yang:Affymax: Employment.

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11

Polster, J., H. Lachmann, and D. Thorburn Burns. "Spectrometric titrations." Analytica Chimica Acta 236 (1990): 510–11. http://dx.doi.org/10.1016/s0003-2670(00)83363-2.

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12

Kaufman, Myron. "Kinetic titrations." Journal of the American Chemical Society 111, no. 18 (August 1989): 6901–5. http://dx.doi.org/10.1021/ja00200a001.

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13

TAMMAR, A. R. "pH/Titrations." Biochemical Society Transactions 13, no. 6 (December 1, 1985): 1253. http://dx.doi.org/10.1042/bst0131253a.

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14

JONSEN, JON. "COMPLEMENT TITRATIONS." Acta Pathologica Microbiologica Scandinavica 37, no. 4 (August 18, 2009): 369–75. http://dx.doi.org/10.1111/j.1699-0463.1955.tb00959.x.

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15

Treadwell, W. D. "Electro-titrations." Journal of the Society of Dyers and Colourists 40, no. 12 (October 22, 2008): 399–406. http://dx.doi.org/10.1111/j.1478-4408.1924.tb01242.x.

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16

Jokic, Anja, Radmila Dzudovic, Ljiljana Jaksic, and Snezana Nikolic-Mandic. "The application of hydrogen-palladium electrode for potentiometric acid-base determinations in tetrahydrofuran." Journal of the Serbian Chemical Society 78, no. 8 (2013): 1203–12. http://dx.doi.org/10.2298/jsc120927018j.

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The application of the hydrogen-palladium electrode (H2/Pd) as the indicator electrode for the determination of relative acidity scale (Es, mV) of tetrahydrofuran (THF) and the potentiometric titrations of acids in this solvent was investigated. The relative acidity scale tetrahydrofuran was determined from the difference half-neutralization potentials of perchloric acid and tetrabutylammonium hydroxide (TBAH), which were measured by using both H2/Pd-SCE and glass-SCE electrode pairs. The experimentally obtained value of Es scale THF with a H2/Pd-SCE electrode pair was 1155 mV, and those obtained with glass-SCE electrode pair 880 mV. By using a H2/Pd indicator electrode, the individual acids (benzoic acid, palmitic acid, maleic acid, acetyl acetone, ?-naphthol) and two component acid mixtures (benzoic acid + ?-naphthol, palmitic acid + ?-naphthol, maleic acid + ?-naphthol and maleic acid + ftalic acid) were titrated with a standard solution of TBAH. In addition, sodium methylate and potassium hydroxide proved to be very suitable titrating agents for titrating of the individual acids and the acids in mixtures, respectively. The relative error of the determination of acids in mixture was less than 3%. The results are in agreement with those obtained by a conventional glass electrode. The advantages of H2/Pd electrode over a glass electrode in potentiometric acid-base determinations in tetrahydrofuran lie in the following: this electrode gives wider relative acidity scale THF, higher the potential jumps at the titration end-point and relatively fast response time; furthermore, it is very durable, simple to prepare and can be used in the titrations of small volumes.

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17

Cassedanne, Jeanníne Odette, and Hamílcar Freire de Carvalho. "Dosagem de chumbo em pequenas quantidades nos minerais." Anuário do Instituto de Geociências 14 (December 1, 1991): 41–43. http://dx.doi.org/10.11137/1991_0_41-43.

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This study describes a lead volumetric titration in minerals. Complexometric accumulation titrations are used and a previous lead separation as chloride is necessary. In the range of 10 to 50 mg of metal, a precision of 0,5 to 0,04% is reached, with a good reproductibility.

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18

Prasad, S., V. D. Leite, R. A. C. Santana, and E. A. Medeiros. "Electrometric studies on formation of cerium vanadates as a function of pH." Eclética Química 31, no. 2 (2006): 31–38. http://dx.doi.org/10.1590/s0100-46702006000200005.

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The precise nature of the reaction between nitric acid and sodium ortho-vanadate solutions has been studied by means of electrometric techniques involving potentiometric and conductometric titrations. The well defined inflections and breaks in the titration curves confirm the existence of the anions, pyro-V2O7(4-), meta-VO3- and poly-H2V10O28(4-) corresponding to the ratios of VO4(3-):H+ as 1:1, 1:2 and 1:2.6 in the neighborhood of pH 10.5, 7.4 and 3.6, respectively. The interaction of cerium(III) nitrate with sodium vanadate solutions, at specific pH levels 12.4, 10.5, 7.4 and 3.6 was also studied by potentiometric and conductometric titrations between the reactants. The end-points obtained from the sharp inflections in the titration curves provide definite evidence for the formation and precipitation of cerium ortho-Ce2O3.V2O5, pyro-2Ce2O3.3V2O5 and meta-Ce2O3.3V2O5 vanadates in the neighborhood of pH 7.4, 6.2 and 4.8, respectively. Analytical investigations on the precipitates formed confirm the results of the electrometric study.

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19

Gündüz, Turgut, Esma Kiliç, Güleren Özkan, Muhammed F. Awaad, and Mustafa Tastekin. "Conductimetric and potentiometric investigation of effect of acidity on formation of homoconjugates in acetonitrile solvent." Canadian Journal of Chemistry 68, no. 5 (May 1, 1990): 674–78. http://dx.doi.org/10.1139/v90-103.

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In the present work, 11 aromatic and nine aliphatic carboxylic acids, namely benzoic, 2-nitrobenzoic, 3-nitrobenzoic, 4-nitrobenzoic, 2,4-dinitrobenzoic, 3,5-dinitrobenzoic, 2-aminobenzoic, 3-aminobenzoic, 4-aminobenzoic, o-phthalic, salicylic, formic, acetic, monochloroacetic, dichloroacetic, trichloroacetic, propionic, n-butyric, caprylic, and myristic acids, were titrated conductimetrically and potentiometrically with triethylamine in acetonitrile solvent, under a nitrogen atmosphere, at 25 °C. Closer investigation of the conductimetric titration curves of these acids showed that the acidity of an acid, rather than the basicity of its conjugate base, plays a major part in the formation of homoconjugate ions, at least in acetonitrile solvent. If the acid is strong enough, there is a maximum before the experimental end point at about the half-neutralization point. To determine the minimum strength for an acid to show this maximum before the end point, all acids were also titrated potentiometrically. It was found that those acids which have half-neutralization potentials over −85 mV give a strong homoconjugation reaction and show a maximum before the experimental end point. Moreover, the acids that show maxima before the experimental end point in the conductimetric titration also show rather well-shaped potentiometric titration curves. Keywords: nonaqueous media, conductimetric titrations, potentiometric titrations, titration in acetonitrile, acidity and homoconjugation.

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20

Zakhari, N. Aziz, and K. Artur Kovar. "Nonaqueous Titration of Halides of Nitrogenous Bases, Using Trifluoromethyl Sulfonic Acid." Journal of AOAC INTERNATIONAL 69, no. 4 (July 1, 1986): 620–24. http://dx.doi.org/10.1093/jaoac/69.4.620.

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Abstract Trifluoromethyl sulfonic acid in glacial acetic acid has been compared with perchloric acid as a titrant in 4 solvent systems: glacial acetic acid, acetic anhydride, a mixture of both, and acetone. The comparison was limited to the determination of halides of nitrogenous bases with and without the use of mercury(II) acetate reagent. The results of the visual titrations showed that both acids are comparable tit rants. However, trifluoromethyl sulfonic acid proved to be superior to perchloric acid in potentiometric titrations carried out in acetic acid-acetic anhydride mixtures. Moreover, the nonoxidizing properties exhibited by trifluoromethyl sulfonic acid proved advantageous over perchloric acid in the visual detection of end points in the titration of phenothiazine derivatives in anhydrous acetic acid, using crystal violet indicator.

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21

Trettnak, Wolfgang, and Otto S. Wolfbeis. "Fibre-optical titrations." Fresenius' Zeitschrift für analytische Chemie 326, no. 6 (January 1987): 547–50. http://dx.doi.org/10.1007/bf00468224.

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22

SUN, Xiao-Bo, Lin LI, Xiu-Xia WANG, and Jin-Pi WANG. "A Universal Model for Titrations and Titration Curves Constructed Using MATLAB." University Chemistry 31, no. 5 (2016): 78–84. http://dx.doi.org/10.3866/pku.dxhx201505015.

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23

Qayoom, Amtul, Syed Arif Kazmi, and Saeeda Nadir Ali. "Turmeric Powder as a Natural Heavy Metal Chelating Agent: Surface Characterisation." Pakistan Journal of Scientific & Industrial Research Series A: Physical Sciences 60, no. 1 (February 28, 2017): 1–8. http://dx.doi.org/10.52763/pjsir.phys.sci.60.1.2017.1.8.

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The present study was conducted to investigate surface properties of turmeric in order to evaluateits detoxification potential and ability to sequester toxic metals ions. Scanning Electron Microscopy (SEM),Energy Dispersion Spectroscopy (EDS), Infra-Red (IR) spectroscopy and potentiometric titrations wereemployed for characterisation of the surface of turmeric powder. Spectroscopic studies revealed that thesurface of turmeric powder was porous mainly composed of polymeric -OH , -NH , -CH2 , -COO and-OH groups of polysaccharides. From potentiometric titrations and modelling of batch titration data, it wasfound that surface of the turmeric contains at least four binding sites with pKa values 3.56 (pK1), 4.83(pK2), 7.68 (pK3) and 10.4 (pK4). Turmeric powder contains highest concentration of amino and hydroxylgroups for the pK4 values i.e., 0.55 mmol/ g. The total binding sites concentration for turmeric powderwas 1.2 mmol/ g.

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24

Pagariya, R. F. "GREEN CHEMISTRY: ROSELLE’S COROLLA EXTRACT AS A SUBSTITUTE FOR HAZARDOUS INTERNAL INDICATORS IN VOLUMETRIC ANALYSIS." International Journal of Research -GRANTHAALAYAH 7, no. 9 (September 30, 2019): 118–22. http://dx.doi.org/10.29121/granthaalayah.v7.i9.2019.567.

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Indicators used in acid-base titration show well marked changes of colour in certain intervals of pH. Most of these indicators are organic dyes and are of synthetic origin. Today synthetic indicators are the choice of neutralization titrations. But due to environmental pollution, availability and cost, the search for natural compounds as an acid-base indicator was started. The present work highlights the use of the ethanolic extract of the corolla of Roselle (Hibiscus sabdariffa) as a pH indicator in strong acid-strong base, strong acid weak base, weak acid strong base and weak acid-weak base titrations. This natural indicator is easy to extract as well as easily available. The results showed that the Roselle’s corolla indicator gave red color in acidic solution, while green in basic solution. The comparison indicators used in this research were phenolphthalein, methyl red and phenol red. Hopeful results were obtained when it was compared against standard synthetic indicators. The equivalence points obtained match with the equivalence points obtained by standard indicators. Therefore this natural indicator is found to be useful, economical, simple, precise and eco-friendly for acid base titration.

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25

Cladera, A., A. Caro, J. M. Estela, and V. Cerdà. "A fully automatic system for acid-base coulometric titrations." Journal of Automatic Chemistry 12, no. 6 (1990): 258–62. http://dx.doi.org/10.1155/s1463924690000323.

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An automatic system for acid-base titrations by electrogeneration of H+and OH-ions, with potentiometric end-point detection, was developed. The system includes a PC-compatible computer for instrumental control, data acquisition and processing, which allows up to 13 samples to be analysed sequentially with no human intervention.The system performance was tested on the titration of standard solutions, which it carried out with low errors and RSD. It was subsequently applied to the analysis of various samples of environmental and nutritional interest, specifically waters, soft drinks and wines.

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26

Golovko, Dmitriy, Virender Sharma, Olga Pavlova, Elena Belyanovskaya, Igor Golovko, Victoria Suprunovich, and Radek Zboril. "Determination of submillimolar concentration of ferrate(VI) in alkaline solutions by amperometric titration." Open Chemistry 9, no. 5 (October 1, 2011): 808–12. http://dx.doi.org/10.2478/s11532-011-0069-8.

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AbstractA new amperometric titration method was developed for quantitative determination of ferrate(VI) (FeVIO42−) in the 7.06×10−5−5.73×10−3 M concentration range. Chromium(III) hydroxide solution was used as the titrant. The diffusion current (Id) had a linear relationship with the concentration of ferrate(VI) and slopes were dependent on the concentration of NaOH. The amperometric titration could detect a lower concentration of ferrate(VI) than could potentiometric and colorimetric titrations. The method was applied successfully to determine concentrations of ferrate(VI), generated electrochemically, in strong alkaline solutions.

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27

Al-Ghannam, Sheikha M., Abdalla M. S. Abulkibash, and Abeer M. Al-Olyyan. "Differential Electrolytic Potentiometric Determination of Some Amino Acids in Dosage Forms." Journal of AOAC INTERNATIONAL 87, no. 3 (May 1, 2004): 671–76. http://dx.doi.org/10.1093/jaoac/87.3.671.

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Abstract The application of direct-current differential electrolytic potentiometry to the nonaqueous titration of amino acids was investigated. The basic character of amino acids in acetic acid was enhanced to permit their direct titration with perchloric acid. A pair of antimony electrodes was used as an indicating system. The shapes of the titration curves obtained were almost symmetrical with sharp peaks. The optimum current density for those titrations was found to be 1–2 μA/cm2. The procedure was applied successfully to the determination of certain amino acids in drug formulations, and the results were favorably compared statistically with those obtained by official methods.

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28

Gaál, F. "Contributions to the theory of catalytic titrations—III Neutralization catalytic titrations." Talanta 32, no. 7 (July 1985): 559–63. http://dx.doi.org/10.1016/0039-9140(85)80143-0.

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29

Wolfbeis, O. "Fibre-optic titrations-IV Direct complexometric titration of aluminium(III) with DCTA." Talanta 33, no. 11 (November 1986): 867–70. http://dx.doi.org/10.1016/0039-9140(86)80214-4.

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30

de Leon, J., Y. L. Tang, T. Baptista, D. Cohen, and P. F. J. Schulte. "Titrating clozapine amidst recommendations proposing high myocarditis risk and rapid titrations." Acta Psychiatrica Scandinavica 132, no. 4 (April 11, 2015): 242–43. http://dx.doi.org/10.1111/acps.12421.

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31

Pereira, R. Calvelo, M. Camps Arbestain, M. Vazquez Sueiro, and J. A. Maciá-Agulló. "Assessment of the surface chemistry of wood-derived biochars using wet chemistry, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy." Soil Research 53, no. 7 (2015): 753. http://dx.doi.org/10.1071/sr14194.

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In order to understand the reactivity of biochar in soil, we thoroughly examined the carbonaceous surface of different biochars, paying particular attention to the distribution of oxygen-containing functional groups. Biochar was produced from pine, poplar and willow at two different temperatures (400 and 550°C) and characterised using elemental analysis and wet chemistry (Boehm and potentiometric titrations, cation-exchange capacity (CEC) measurement). In addition, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses were performed on both untreated and acid-washed biochar samples. Qualitative relationships were observed between data generated from the titration methods under investigation and XPS analyses, both describing the general distribution of oxygen-containing surface functional groups. Total acidity of biochar ranged widely, between 32 and 1067 mmol kg–1, and was mostly attributed to the presence of hydroxyl or phenol groups. The number of functional groups containing oxygen decreased with increasing pyrolysis temperature, mainly because of a decrease in the content of phenol groups. A quantitative comparison of titrations and CEC (i.e. biochar’s ion-exchange capacity) measurements was compromised by a masking effect caused by the biochar’s inorganic fraction (<8%). An acid-washing step with nitric acid was shown not to alter the biochar surface systematically. The use of potentiometric titrations with an acid-washing pretreatment proved to be suitable to quantify biochar acidic functional groups, and hence biochar acidity.

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32

Boyette, S. M., J. M. Lovett, W. G. Gaboda, and J. A. Soares. "Cell surface and exopolymer characterization of laboratory stabilized activated sludge from a beverage bottling plant." Water Science and Technology 43, no. 6 (March 1, 2001): 175–84. http://dx.doi.org/10.2166/wst.2001.0369.

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Fermentor-stabilized activated sludge from an industrial beverage bottling plant was grown on three different food sources: normal plant wastewater, plant wastewater containing high sucrose concentrations, and a synthetic glucose-based feed stock. Surface charge, hydrophobicity, and exopolysaccharide composition were measured on the stabilized bacterial flocs. Cell surface charge was measured by electrophoretic mobility, dye exchange titration, and a standard colloid titration, while cell hydrophobicity was determined using the bacterial adhesion to hydrocarbons (BATH) test. Exopolysaccharide profiles were determined by measuring concentrations of glucose, galactose, mannose, glucuronic, and galacturonic acids in digested exopolymer extractions using HPLC. Changes in the physical surface properties of the bacteria and the chemical composition of the extracted exopolymers were correlated with differences in the three food sources. Cell surface hydrophobicity was similar for cultures grown on different plant wastewaters, while the culture grown on synthetic food produced less floc hydrophobicity. Electrophoretic mobility measurements, charge titrations, and dye exchange titrations showed different total surface charge as well as varying charge availability. Additionally, total surface charge and total exopolysaccharide concentrations appeared less dependent on food source than the food-to-mass ratio. High concentrations of biodegradable food produced dispersed growth and high concentrations of exopolysaccharides that contributed to poor settling.

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33

Chen, Po-chia, Pawel Masiewicz, Kathryn Perez, and Janosch Hennig. "Structure-based screening of binding affinities via small-angle X-ray scattering." IUCrJ 7, no. 4 (May 6, 2020): 644–55. http://dx.doi.org/10.1107/s2052252520004169.

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Protein–protein and protein–ligand interactions often involve conformational changes or structural rearrangements that can be quantified by solution small-angle X-ray scattering (SAXS). These scattering intensity measurements reveal structural details of the bound complex, the number of species involved and, additionally, the strength of interactions if carried out as a titration. Although a core part of structural biology workflows, SAXS-based titrations are not commonly used in drug discovery contexts. This is because prior knowledge of expected sample requirements, throughput and prediction accuracy is needed to develop reliable ligand screens. This study presents the use of the histidine-binding protein (26 kDa) and other periplasmic binding proteins to benchmark ligand screen performance. Sample concentrations and exposure times were varied across multiple screening trials at four beamlines to investigate the accuracy and precision of affinity prediction. The volatility ratio between titrated scattering curves and a common apo reference is found to most reliably capture the extent of structural and population changes. This obviates the need to explicitly model scattering intensities of bound complexes, which can be strongly ligand-dependent. Where the dissociation constant is within 102 of the protein concentration and the total exposure times exceed 20 s, the titration protocol presented at 0.5 mg ml−1 yields affinities comparable to isothermal titration calorimetry measurements. Estimated throughput ranges between 20 and 100 ligand titrations per day at current synchrotron beamlines, with the limiting step imposed by sample handling and cleaning procedures.

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34

Prasad, S., R. A. C. Santana, A. R. N. Campos, and V. D. Leite. "Potentiometric and conductometric studies on the system acid-isopolytungstate and the formation of lanthanum tungstates." Eclética Química 32, no. 1 (2007): 71–78. http://dx.doi.org/10.1590/s0100-46702007000100010.

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The stoichiometry of the polyanions formed by the action of nitric acid on sodium tungstate (< 0.01M) has been studied by means of electrometric techniques involving pH-potentiometric and conductometric titrations. The well defined inflections and breaks in the titration curves provide evidence for the existence of the polyanions, para-W12O41(10-) and meta-W12O39(6-) corresponding to the ratio of H+:WO4(2-) as 7:6 and 9:6 in the pH ranges 5.7-6.0 and 3.6-4.1, respectively. The interaction of lanthanum nitrate with sodium tungstate solutions, at specific pH levels 8.0, 5.9 and 4.0 was also studied by pH and conductometric titrations, in aqueous and alcoholic media, with each of the reagents alternatively used as titrant. The electrometric experiments provide definite evidence of the formation of normal-La2O3.3WO3, para-5La2O3.36WO3 and meta-La2O3.12WO3 tungstates in the vicinity of pH 6.3, 5.0 and 4.2, respectively. Analytical investigations on the precipitates formed confirm the results of the electrometric study.

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35

Yao, Shou-Zhuo, Zhi-Hong Mo, and Li-Hua Nie. "Titrations with piezoelectric monitoring." Analytica Chimica Acta 230 (1990): 51–58. http://dx.doi.org/10.1016/s0003-2670(00)82760-9.

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Yao, Shou-Zhuo, Zhi Hong Mo, and Li-Hua Nie. "Titrations with piezoelectric monitoring." Analytica Chimica Acta 229 (1990): 205–12. http://dx.doi.org/10.1016/s0003-2670(00)85130-2.

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37

Gaál, Ferenc F. "Catalytic titrations. Plenary lecture." Analyst 112, no. 6 (1987): 739–51. http://dx.doi.org/10.1039/an9871200739.

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DeGrandpre, Michael D., Todd R. Martz, Robert D. Hart, David M. Elison, Alice Zhang, and Anna G. Bahnson. "Universal Tracer Monitored Titrations." Analytical Chemistry 83, no. 24 (December 15, 2011): 9217–20. http://dx.doi.org/10.1021/ac2025656.

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39

Sasaki, Milton K., Diogo L. Rocha, Fábio R. P. Rocha, and Elias A. G. Zagatto. "Tracer-monitored flow titrations." Analytica Chimica Acta 902 (January 2016): 123–28. http://dx.doi.org/10.1016/j.aca.2015.10.036.

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Taylor, Richard H., Jaromir Růžička, and Gary D. Christian. "Flow-injection coulometric titrations☆." Talanta 39, no. 3 (March 1992): 285–92. http://dx.doi.org/10.1016/0039-9140(92)80034-b.

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Braun, R. D. "Potentiometry and potentiometric titrations." TrAC Trends in Analytical Chemistry 4, no. 5 (May 1985): xxi. http://dx.doi.org/10.1016/0165-9936(85)87014-x.

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Gaiao, Edvaldo da Nobrega, Valdomiro Lacerda Martins, Wellington da Silva Lyra, Luciano Farias de Almeida, Edvan Cirino da Silva, and Mário César Ugulino Araújo. "Digital image-based titrations." Analytica Chimica Acta 570, no. 2 (June 2006): 283–90. http://dx.doi.org/10.1016/j.aca.2006.04.048.

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43

Vasilyeva, Marina S., Vladimir S. Rudnev, E. S. Zykova, Alexander Yu Ustinov, Ksenia A. Sergeeva, A. V. Nepomnyaschiy, I. V. Lukiyanchuk, and Galina I. Marinina. "Ti/TiO₂, Au Electrodes Prepared by Plasma Electrolytic Oxidation and Electron Beam Evaporation." Defect and Diffusion Forum 386 (September 2018): 326–31. http://dx.doi.org/10.4028/www.scientific.net/ddf.386.326.

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Ti/TiO2,Au electrodes were prepared via plasma electrolytic oxidation (PEO) of Ti plate, followed by deposition of a thin (10 nm) Au layer by electron beam evaporation (EBE). The electrodes obtained were used for potentiometric indication of different types of chemical reactions. Ti/TiO2,Au electrodes showed an excellent performance for end point indication in the oxidation-reduction and complexometric titrations similar to the traditional Pt and in the acid-base titration similar to glass electrode.

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Cavalcanti, Bernadete F., Lourdes Cristina Lucena Agostinho, and Luciano Nascimento. "DETERMINATION OF ALKALINITY AND DISSOCIATION CONSTANTS OF HIGH SALINITY WATERS: USE OF F5BC TITRATION FUNCTION." Eclética Química Journal 35, no. 2 (January 16, 2018): 79. http://dx.doi.org/10.26850/1678-4618eqj.v35.2.2010.p79-87.

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Measurements of parameters expressed in terms of carbonic species such as Alkalinity and Acidity of saline waters do not analyze the influence of external parameters to the titration such as Total free and associated Carbonic Species Concentration, activity coefficient, ion pairing formation and Residual Liquid Junction Potential in pH measurements. This paper shows the development of F5BC titration function based on the titrations developed by Gran (1952) for the carbonate system of natural waters. For practical use, samples of saline watersfrom Pocinhos reservoir in Paraiba were submitted to titration and linear regression analysis. Results showed that F5BC involves F1x and F2x Gran functions determination, respectively, for Alkalinity and Acidity calculations without knowing “a priori” the endpoint of the titration. F5BC also allows the determination of the First and Second Apparent Dissociation Constant of the carbonate system of saline and high ionic strength waters.

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Jo, K. "Continuous on-line feedback based flow titrations. Complexometric titrations of calcium and magnesium." Talanta 60, no. 1 (May 28, 2003): 131–37. http://dx.doi.org/10.1016/s0039-9140(03)00114-0.

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46

Abramovic, B. "Contributions to the theory of catalytic titrations—II Precipitation and redox catalytic titrations." Talanta 32, no. 7 (July 1985): 549–58. http://dx.doi.org/10.1016/0039-9140(85)80142-9.

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47

Kuselman, Ilya, Felix Sherman, Tat’Yana Bourenko, and Avinoam Shenhar. "Simultaneous Determination of Water and Enediols or Thiols in Chemical Products and Drugs Not Amenable to Direct Karl Fischer Titration." Journal of AOAC INTERNATIONAL 82, no. 4 (July 1, 1999): 840–61. http://dx.doi.org/10.1093/jaoac/82.4.840.

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Abstract A method proposed for determining water and enediols or thiols is based on consecutive titration of the enediols or thiols by a novel reagent and of water by the conventional Karl Fischer reagent in the same cell. The time for both titrations is 8–20 min. The novel reagent consists of iodine, sodium acetate as a base, and potassium iodide in a nonaqeous solvent system. The method is applicable for quality control of chemical products and drugs during their production and trade.

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48

Liu, Xing Xin, and Artem Melman. "Formation of Ternary Complexes of Iron(III) Cations in Solution and Gas Phase." Australian Journal of Chemistry 66, no. 7 (2013): 791. http://dx.doi.org/10.1071/ch13179.

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Formation of labile 1 : 1 : 1 ternary mononuclear complexes of iron(iii) cation with η3-terdentate meridional binders was studied using electrospray ionisation mass spectrometry (ESI-MS) titration and UV-Vis titration in solution phase. Low selectivities towards formation of ternary heteroleptic complexes in the solution phase vs. symmetric 2 : 1 complexes were obtained with combinations of dianionic 2,6-bis[hydroxy(methyl)amino]-1,3,5-triazine (BHT) ligands with monoanionic terdentate ligands such as 2-[(2-pyridinylmethylene)amino]phenol. Moderate selectivities were observed in formation of ternary iron(iii) complexes of iron(iii) between BHT ligands and neutral terdentate ligands such as pyridin-2-ylmethylpyridin-2-ylmethyleneamine. Results obtained by MS titrations were in a reasonable agreement with UV titration data indicating that quantitative ESI MS spectrometry can be applied to these labile iron(iii) complexes.

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Rodríguez-Laguna, Norma, Alberto Rojas-Hernández, María Teresa Ramírez-Silva, Lucero Hernández-García, and Mario Romero-Romo. "An Exact Method to Determine the Conductivity of Aqueous Solutions in Acid-Base Titrations." Journal of Chemistry 2015 (2015): 1–13. http://dx.doi.org/10.1155/2015/540368.

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Several works in the literature show that it is possible to establish the analytic equations to estimate the volumeVof a strong base or a strong acid (VbandVa, resp.) being added to a solution of a substance or a mix of substances during an acid-base titration, as well as the equations to estimate the first derivative of the titration plotdpH/dV, and algebraic expressions to determine the bufferβcapacity with dilutionβdil. This treatment allows establishing the conditions of thermodynamic equilibria for all species within a system containing a mix of species from one or from various polyacid systems. The present work shows that it is possible to determine exactly the electric conductivity of aqueous solutions for these Brønsted acid-base titrations, because the functional relation between this property and the composition of the system in equilibrium is well known; this is achieved using the equivalent conductivityλivalues of each of the ions present in a given system. The model employed for the present work confirms the experimental outcomes with the H2SO4, B(OH)3, CH3COOH, and H3PO4aqueous solutions’ titration.

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HE, Qing-Yu, Anne B. MASON, and Robert C. WOODWORTH. "Spectrophotometric titration with cobalt(III) for the determination of accurate absorption coefficients of transferrins." Biochemical Journal 318, no. 1 (August 15, 1996): 145–48. http://dx.doi.org/10.1042/bj3180145.

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A rapid and sensitive technique, involving difference spectral titration with cobalt(III), to measure the ϵ values of chicken ovotransferrin, human serum transferrin, the N-lobe of human transferrin and several single point mutants is reported. The resulting ϵ values were compared with the values calculated from the equation proposed by Pace, Vajdos, Fee, Grimsley and Gray [(1995) Protein Sci. 4, 2411–2423]. The titrations with cobalt feature sharp break-points and do not destroy the protein samples. The choice of buffer was found to be important, depending on the metal-binding avidity of the proteins. Cobalt titration should prove useful for studying the comparative metal-binding properties of transferrin and mutants of transferrin being generated by recombinant technology.

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