scholarly journals Determination of Trace Amounts of Hydrofluoric Acid in Non-Aqueous Solutions by the Coulometric Titration Method

Sensors ◽  
2018 ◽  
Vol 18 (12) ◽  
pp. 4439 ◽  
Author(s):  
Cairui Huang ◽  
Congcong Shen ◽  
Ling Jin ◽  
Hongwei Cai
Keyword(s):  
Aqueous Solutions ◽  
Hydrofluoric Acid ◽  
Coulometric Titration ◽  
Accurate Determination ◽  
Ethanol Solution ◽  
Constant Current ◽  
Electrode Pair ◽  
Working Electrode ◽  
Relative Standard

For monitoring of trace amounts of hydrofluoric acid in the organic fluorine chemical industry, a facile method for determination of the hydrofluoric acid in an ethanol solution of lithium chloride, by coulometric titration, was proposed. Relying on homemade acid–base coulometric autotitrator, the electrolyte was 0.50 mol·L−1 LiCl ethanol solution and the constant current intensity was 0.2–2 mA. As for the working electrode pair, a platinum plate was used as a working electrode, and a platinum wire was used as an auxiliary electrode. The indicating electrode was the pH composite glass electrode and the titration endpoint was pH 5.50. The results showed that the relative standard deviation was below 2.0%, as the content of the hydrofluoric acid was between 2 μg to 100 μg. The recovery rate was 99.0–102.0%. This proposed route has the advantages of simplicity, convenience, quickness, accuracy, and automation, which can be applied to the accurate determination of trace amounts of hydrofluoric acid, in non-aqueous solutions.

2-Monochloropropanediol (2-MCPD), 3-Monochloropropanediol (3-MCPD), and Glycidol in Infant and Adult/Pediatric Nutritional Formula: Single-Laboratory Validation, First Action 2018.12

2019 ◽  
Vol 102 (4) ◽  
pp. 1205-1220 ◽  
Author(s):  
Jan Kuhlmann
Keyword(s):  
Fatty Acid ◽  
Infant Formula ◽  
Edible Oils ◽  
Accurate Determination ◽  
Fatty Acid Esters ◽  
Method Performance ◽  
Relative Standard ◽  
Single Laboratory ◽  
Acid Esters

Abstract Background: Fatty acid esters of glycidol, 2-Monochloropropanediol (MCPD), and 3-MCPD are heat-induced foodborne processing contaminants with possible adverse health effects. These compounds occur frequently in refined edible oils. Consequently, glycidyl esters and 2- and 3-MCPD esters might also be present in foods that contain refined edible oils. Objective: This manuscript describes the single-laboratory validation of an analytical method for the quantitative determination of glycidol, 2-MCPD, and 3-MCPD present as fatty acid esters or as free 2- or 3-MCPD in infant and adult/pediatric nutritional formula. Methods: Technically, the presented method is based on the combination of a Heat-Ultrasound Pressure-supported Solvent Extraction and a GC–MS determination of glycidol, 2-MCPD, and 3-MCPD. From a chemical perspective, the method includes an alkaline catalyzed transesterification, conversion of the unstable glycidol into monobromopropanediol, and the parallel derivatization of all analytes with phenylboronic acid. Results: Validation results showed that method linearity for all analytes in powdered and liquid infant formula ranged from 0.9981 to 0.9999 (n = 18). Repeatability relative standard deviation values for concentration levels between 1.3 μg/kg and 331 μg/kg were in the range of 1 to 12%. Relative recoveries were found to be between 93 and 107%. The analytes were quantifiable down to 5–10 μg/kg in powdered samples and 1–2 μg/kg in liquid samples. Conclusions: The reported results met actual AOAC Standard Method Performance Requirements. Highlights: In terms of consumer protection, the presented method is a novel approach for the sensitive and accurate determination of glycidol, 2-MCPD, and 3-MCPD in infant formula and related foodstuffs.

scholarly journals Development of a chiral HPLC method for the separation and quantification of hydroxychloroquine enantiomers

2020 ◽  
Author(s):  
Xisheng Xiong ◽  
Kun Wang ◽  
Tao Tang ◽  
Jinzhi Fang ◽  
Yijun Chen
Keyword(s):  
Accurate Determination ◽  
Hplc Method ◽  
Normal Phase ◽  
Optical Isomers ◽  
Chiral Hplc ◽  
Potential Treatment ◽  
Limit Of Quantification ◽  
Relative Standard ◽  
Clinical Benefits

Abstract Hydroxychloroquine (2-[[4-[(7-Chloroquinolin-4-yl) amino]pentyl](ethyl) amino]-ethanol, HCQ), an effective anti-malarial drug, has been applied in the clinics for potential treatment of severe coronavirus disease 2019 (COVID-19). Although the clinical benefits of HCQ require extensive clinical data to confirm, the existence of a chiral center in the molecule to possess two optical isomers suggests that there might be an enantiomeric difference on the treatment of COVID-19. Due to poor resolution and the inability of quantification by previously reported methods for the analysis of HCQ enantiomers, it is necessary to develop an analytical method to achieve baseline separation for quantitative and accurate determination of the enantiomeric purity in order to compare the efficacy and toxicity profiles of different enantiomer. In this study, we developed and validated an accurate and reproducible normal phase chiral HPLC method for the analysis of two enantiomers of HCQ, and the method was further evaluated with biological samples. With this newly developed method, the relative standard deviation of all analytes was lower than 5%, and the limit of quantification was 0.27 μg/ml, 0.34 μg/ml and 0.20 μg/ml for racemate, R- and S-enantiomer, respectively. The present method provides an essential analytical tool for preclinical and clinical evaluation of HCQ enantiomers for potential treatment of COVID-19.

Iodometric determination of 2-mercaptobenzthiazole by coulometric titration

1982 ◽  
Vol 47 (2) ◽  
pp. 588-593 ◽  
Author(s):  
Zdeněk Kučera ◽  
Milan Karlík ◽  
Jiří Krofta
Keyword(s):  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Coulometric Titration ◽  
Optimum Conditions ◽  
End Point ◽  
Relative Standard ◽  
Standard Deviations

The optimum conditions were found for the determination of 2-mercaptobenzthiazole (MBT) by coulometric titration with the generated iodine using biamperometric indication of the titration end point. Use is made of the oxidation to the disulphide (n = 1) and to benzothiazole-2-sulphinate (n = 4) in the regions pH 4.5-8.5 and 10-12, respectively. Eight repeated titrations to the disulphide gave the relative standard deviations 0.27% and 1.23% in the determination of 1 675 and 33.5 μg MBT, respectively, seven repeated titrations of 419 μg MBT to benzothiazole-2-sulphinate afforded results with the relative standard deviation 0.34%.

Headspace Gas Chromatographic Estimation of Some Yogurt Volatiles

1991 ◽  
Vol 74 (4) ◽  
pp. 630-634 ◽  
Author(s):  
Franz Ulberth
Keyword(s):  
Accurate Determination ◽  
Standard Addition ◽  
Calibration Method ◽  
Relative Standard ◽  
Headspace Gas ◽  
Standard Calibration ◽  
Gas Chromatographic Method ◽  
Aroma Components ◽  
Ppm Level

Abstract A headspace gas chromatographic method Is described for the determination of acetaldehyde, ethanol, acetone, dlacetyl, and 2-butanone In yogurt. Yogurt (2 g) is equilibrated 1 h in a 10 mL vial at 60 °C, and 0.25 mL headspace gas Is splitinjected. The volatiles are baseline-separated In less than 5 min by using a thick film capillary column coated with SE-54. An external standard calibration method fulfills the requirements for an accurate determination of the yogurt aroma components. The accuracy of this method was checked by the standard addition method. The precision of the method, In terms of the relative standard deviation, depends on the analyte concentration. At the 10 ppm volatile level, RSD Is 2%, and at the 0.1 ppm level, 15%.

Zinc oxide impregnated resin for preconcentration and spectrophotometric determination of uranyl ions in aqueous solutions

2018 ◽  
Vol 106 (7) ◽  
pp. 569-579
Author(s):  
O. A. Elhefnawy ◽  
A. A. Elabd
Keyword(s):  
Aqueous Solutions ◽  
Spectrophotometric Determination ◽  
Adsorption Process ◽  
Fourier Transforms ◽  
Sol Gel ◽  
Uranyl Ions ◽  
X Ray ◽  
Relative Standard ◽  
Impregnated Resin

Abstract The objective of this work is to find a new, efficient and alternate low-cost adsorbent for preconcentration and spectrophotometric determination of uranyl ions U(VI) from aqueous solution. For this reason the new impregnated resin (ZnO/7HP) has been prepared by sol-gel technique. Characterization of ZnO/7HP was conducted using scanning electron microscopy/energy-dispersive X-ray spectrometer and X-ray diffraction, and Fourier transforms infrared spectroscopy. Several important parameters influencing the U(VI) adsorption such as pH, adsorbent amount, initial U(VI) concentration, contact time and temperature were investigated systematically by batch experiments. The obtained results showed that the equilibrium adsorption data were well fitted to the Langmuir model with a maximum adsorption amount of 24.96 mg/g. While the adsorption kinetics data were described well by the pseudo-second order model. This result indicates that the adsorption process is chemisorption. Thermodynamic results indicate that the U(VI) adsorption process is endothermic nature and favors at high temperature. Hydrochloric acid was used for preconcentration of U(VI) and detected spectrophotometry after the reaction with Arsenazo III. According to the definition of International Union of Pure and Applied Chemistry, the detection limit of this method was 0.12 μg/L. The relative standard deviation under optimum conditions is less than 3.0 % (n=5). The new impregnated resin ZnO/7HP is a promising adsorbent for preconcentration and spectrophotometric determination of U(VI) in aqueous solutions.

Ion chromatography as highly suitable method for rapid and accurate determination of antibiotic fosfomycin in pharmaceutical wastewater

2014 ◽  
Vol 69 (10) ◽  
pp. 2014-2022 ◽  
Author(s):  
Ping Zeng ◽  
Xiaolin Xie ◽  
Yonghui Song ◽  
Ruixia Liu ◽  
Chaowei Zhu ◽  
...  
Keyword(s):  
Ion Chromatography ◽  
Industrial Wastewater ◽  
High Performance ◽  
Limit Of Detection ◽  
Batch Reactor ◽  
Accurate Determination ◽  
Pharmaceutical Wastewater ◽  
Relative Standard ◽  
High Detection Limit

A rapid and accurate ion chromatography (IC) method (limit of detection as low as 0.06 mg L−1) for fosfomycin concentration determination in pharmaceutical industrial wastewater was developed. This method was compared with the performance of high performance liquid chromatography determination (with a high detection limit of 96.0 mg L−1) and ultraviolet spectrometry after reacting with alizarin (difficult to perform in colored solutions). The accuracy of the IC method was established in the linear range of 1.0–15.0 mg L−1 and a linear correlation was found with a correlation coefficient of 0.9998. The recoveries of fosfomycin from industrial pharmaceutical wastewater at spiking concentrations of 2.0, 5.0 and 8.0 mg L−1 ranged from 81.91 to 94.74%, with a relative standard deviation (RSD) from 1 to 4%. The recoveries of effluent from a sequencing batch reactor treated fosfomycin with activated sludge at spiking concentrations of 5.0, 8.0, 10.0 mg L−1 ranging from 98.25 to 99.91%, with a RSD from 1 to 2%. The developed IC procedure provided a rapid, reliable and sensitive method for the determination of fosfomycin concentration in industrial pharmaceutical wastewater and samples containing complex components.

scholarly journals Fabrication of an Immobilized Polyelectrolite Complex (PEC) Membrane from Pectin-Chitosan and Chromoionophore ETH 5294 for pH-Based Fish Freshness Monitoring

Coatings ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 88
Author(s):  
Eka Safitri ◽  
Zatul Omaira ◽  
Nazaruddin Nazaruddin ◽  
Irfan Mustafa ◽  
Sitti Saleha ◽  
...  
Keyword(s):  
Accurate Determination ◽  
Active Material ◽  
Ph Sensor ◽  
Wavelength Region ◽  
Trial And Error ◽  
Optimum Conditions ◽  
Relative Standard ◽  
Optimum Wavelength ◽  
Optical Ph Sensor

Considering the significance of its demand around the world, the accurate determination of fish freshness with a simple and rapid procedure has become an interesting issue for the fishing industry. Hence, we aimed to fabricate a new optical pH sensor based on a polyelectrolyte (PEC) membrane of pectin–chitosan and the active material chromoionophore ETH 5294. A trial-and-error investigation of the polymer compositions revealed that the optimum ratio of pectin to chitosan was 3:7. With an optimum wavelength region (λ) at 610 nm, the constructed sensor was capable of stable responses after 5 min exposure to phosphate-buffered solution. Furthermore, the obtained sensor achieved optimum sensitivity when the PBS concentration was 0.1 M, while the relative standard deviation values ranged from 2.07 to 2.34%, suggesting good reproducibility. Further investigation revealed that the sensor experienced decreased absorbance of 16.67–18.68% after 25 days of storage. Employing the optimum conditions stated previously, the sensor was tested to monitor fish freshness in samples that were stored at 4 °C and ambient temperature. The results suggested that the newly fabricated optical sensor could measure pH changes on fish skin after 25 h storage at room temperature (pH 6.37, 8.91 and 11.02, respectively) and 4 °C (pH 6.8, 7.31 and 7.92, respectively).

Determination of Iodide in Nutritional Beverage Products Using an Ion Selective Electrode

1978 ◽  
Vol 61 (6) ◽  
pp. 1366-1369 ◽  
Author(s):  
Preston Miles
Keyword(s):  
Neutron Activation Analysis ◽  
Standard Deviation ◽  
Accurate Determination ◽  
Ion Selective Electrode ◽  
Selective Electrode ◽  
Relative Standard ◽  
Dry Ashing ◽  
Nutritional Beverage ◽  
Ppm Level

Abstract An ion selective electrode procedure is described for the precise, accurate determination of iodide at the sub-ppm level in a variety of nutritional beverages. The relative standard deviation of the analysis is 1-4%; recoveries range from 90 to 120%. Comparison with results from neutron activation analysis and the traditional Sandell-Kolthoff procedure shows that the ion selective electrode procedure is free of determinant error and that dry ashing of samples can lead to low results.

Sign in / Sign up

Export Citation Format

Share Document