scholarly journals A general strategy for the voltammetric trace determination of tellurium in geochemical and environmental matrices after arsenic coprecipitation and critical assessment of digestion schemes

2020 ◽  
Vol 17 (2) ◽  
pp. 85 ◽  
Author(s):  
Marc Biver ◽  
Montserrat Filella
Keyword(s):  
Reference Materials ◽  
Limit Of Detection ◽  
Chemical Elements ◽  
Certified Reference Materials ◽  
Anodic Stripping Voltammetry ◽  
General Strategy ◽  
Environmental Matrices ◽  
Hypophosphorous Acid ◽  
Sample Digestion

Environmental contextAmong chemical elements classified as elements of strategic importance, tellurium is rapidly becoming an emergent contaminant. There is, however, no accurate and sensitive method for measuring tellurium concentrations in environmental and geological samples (e.g., soils, sediments), and thus it is not possible to determine whether an ecosystem is being polluted by human activities. This study provides a reliable answer to this problem. AbstractA general method is proposed for the determination of tellurium in environmental and geochemical samples. Samples may be digested by any technique (acid or fusion digestion). The tellurium in the resulting solution is reductively coprecipitated with added arsenite by hypophosphorous acid, and the precipitate is redissolved and analysed by catalytic anodic stripping voltammetry. Several sample digestion techniques (acid and fusion digestions) are critically assessed. The method is applied to ore certified reference materials, with tellurium concentrations spanning three orders of magnitude, and sediment certified reference materials (ocean, lake and estuarine). An overall limit of detection (LOD) of 5 ppb is achieved. Acid digestion by H2SO4 and by HClO4 or sintering with Na2O2 in glassy carbon crucibles are shown to be the most adequate sample digestion techniques.

Thallium fractionation in polluted environmental samples using a modified BCR three-step sequential extraction procedure and its determination by electrothermal atomic absorption spectrometry

2008 ◽  
Vol 62 (2) ◽  
Author(s):  
Ján Medved’ ◽  
Milan Kališ ◽  
Ingrid Hagarová ◽  
Peter Matúš ◽  
Marek Bujdoš ◽  
...  
Keyword(s):  
Sequential Extraction ◽  
Reference Materials ◽  
Environmental Samples ◽  
Limit Of Detection ◽  
Certified Reference Materials ◽  
Electrothermal Atomic Absorption Spectrometry ◽  
Extraction Procedure ◽  
Sequential Extraction Procedure ◽  
Residual Fraction

AbstractDetermination of thallium in polluted environmental samples and their extracts obtained by a modified BCR three-step sequential extraction procedure was used to study thallium distribution and mobility in the monitored polluted area affected by acidification (Šobov, Central Slovakia). The results of fractionation applied to 5 soil certified reference materials and 14 environmental samples show that the vast majority of thallium occurred in the residual fraction. This means that highly toxic thallium is strongly entrapped in the parent rock materials remains immobile and its environmental toxicity is therefore reduced. The limit of detection for thallium in the studied fractions was lower than 0.050 mg kg−1, the precision (RSD) of the ultratrace determination of thallium in the studied fractions was better than 17 % and the accuracy of the used method was verified by analyzing certified reference materials.

scholarly journals Reference materials for the determination of contaminants in milk and milk products

2011 ◽  
Vol 21 (No. 3) ◽  
pp. 111-120
Author(s):  
J. Táborský ◽  
A. Hejtmánková ◽  
J. Dolejšková
Keyword(s):  
Polychlorinated Biphenyls ◽  
Organochlorine Pesticides ◽  
Reference Materials ◽  
Chemical Elements ◽  
Certified Reference Materials ◽  
Basic Information ◽  
Milk Products

In this review, the latest information is given about the reference materials for the determination of contaminants in milk and milk products. Certified reference materials for the determination of contaminating chemical elements, organochlorine pesticides, polychlorinated biphenyls, dibenzodioxins, dibenzofurans, and aflatoxin M<sub>1</sub> are presently available. Properties of these reference materials and possibilities for their use are discussed together with the maximum tolerances of contaminants in milk and milk products. The basic information about the producers and distributors of the reference materials in this area is provided. &nbsp;

APPLICATION OF AAS AND NAA FOR DETERMINATION OF TIN IN SRMs, AND IN ANIMAL AND HUMAN ORGANS

1992 ◽  
Vol 02 (04) ◽  
pp. 489-491 ◽  
Author(s):  
MOMOKO CHIBA ◽  
VENKATESH G. IYENGAR
Keyword(s):  
Neutron Activation Analysis ◽  
Activation Analysis ◽  
Reference Materials ◽  
Certified Reference Materials ◽  
Analytical Techniques ◽  
Absorption Spectrometry ◽  
Dry Weight ◽  
Mixed Diet ◽  
Human Organs

Tin (Sn) is one of the causative elements of the environmental pollution. As no certified reference materials for Sn are presently available, existing reference materials were analyzed for Sn by two independent analytical techniques; atomic absorption spectrometry (AAS) and neutron activation analysis (NAA). The results obtained by both methods were in agreement except for mixed diet which contains Sn in the range of 50 μ g/g. Further, tin concentrations in human and animal organs have been examined by AAS. Among organs tested tin concentrations in testes were the highest, 2.08±0.62 μ g/g dry weight (mean ±SD, n=12) in humans, and 1.45±0.55 μ g/g (n=8) in mice.

scholarly journals Cost-effective Method of Analysis for the Determination of Cadmium, Copper, Nickel and Zinc in Cocoa Beans and Chocolates

2014 ◽  
Vol 4 (1) ◽  
pp. 193 ◽  
Author(s):  
Gideon Ramtahal ◽  
Ivan Chang Yen ◽  
Isaac Bekele ◽  
Frances Bekele ◽  
Lawrence Wilson ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Reference Materials ◽  
Certified Reference Materials ◽  
Control Sample ◽  
Cost Effective ◽  
Cocoa Beans ◽  
Copper Nickel ◽  
Flame Atomic Absorption

<p>The determination of heavy metals in cocoa beans and chocolates is of great importance, due to increasingly stringent regulations being implemented by international legislative bodies and chocolate manufacturers, to protect the health of their consumers. While various techniques exist for heavy metal analyses in cocoa, this study developed a cost-effective, accurate and precise method capable of processing up to 120 samples per batch for the determination of cadmium, copper, nickel and zinc. For sample extractions, a normal laboratory hot plate and locally fabricated high-capacity digestion blocks were used, instead of dedicated block digestion or microwave digestion systems. In addition, only concentrated nitric acid was used, instead of mixed reagents used in standardized methods, for metal extractions from samples, with a sample: extractant ratio of 0.5 g : 10 mL, digestion at 130 ºC, followed by filtration and analysis by flame atomic absorption spectrophotometry. The method was validated with Certified Reference Materials, with heavy metal recoveries generally &gt;95%. Additionally, an in-house quality control sample of ground cocoa nib analyzed together with the Certified Reference Materials was used to monitor the consistency of analyses of heavy metals in cocoa bean samples.</p>

scholarly journals Microfabricated Au-Film Sensors for the Voltammetric Determination of Hg(II)

Proceedings ◽  
2018 ◽  
Vol 2 (13) ◽  
pp. 1518
Author(s):  
Maria Tsetsoni ◽  
Eleni Roditi ◽  
Christos Kokkinos ◽  
Anastasios Economou
Keyword(s):  
Electrode Surface ◽  
Limit Of Detection ◽  
Anodic Stripping Voltammetry ◽  
Stripping Voltammetry ◽  
Voltammetric Determination ◽  
Film Sensor ◽  
Au Film ◽  
Working Electrode ◽  
Anodic Stripping

In this work, a microfabricated Au-film sensor was designed and fabricated for thevoltammmetric determination of Hg(II). The electrode was fabricated on a silicon chip with astandard microengineering approach utilizing photolithography for patterning the electrode shapeand sputtering for deposition of thin Cr and Au films on the surface of the sensors. The sensorswere used for the determination of trace Hg(II) with anodic stripping voltammetry (ASV): initiallyHg(II) in the sample was accumulated on the Au working electrode surface by reduction andformation of an Au(Hg) amalgam followed by oxidation of the preconcentrated metallic Hg using asquare wave voltammetric scan. The limit of detection was 1.5μgL−1 and the coefficient of variationof 10 consecutive measurements was 3.1%.

Evaluation of Automated Sample Preparation for Mycotoxin Analysis in Foods

2020 ◽  
Vol 103 (4) ◽  
pp. 1052-1059 ◽  
Author(s):  
Kai Zhang
Keyword(s):  
Sample Preparation ◽  
Reference Materials ◽  
Certified Reference Materials ◽  
Peanut Butter ◽  
Method Performance ◽  
Robotic Arms ◽  
Automated Sample Preparation ◽  
Sample Preparation Procedure ◽  
Mycotoxin Analysis

Abstract Background In the present study, we developed a novel automated sample preparation workflow for the determination of mycotoxins in foods. Objective This workflow integrates off-line devices such as a centrifuge, shaker, liquid and solid dispensing units into a unified platform to perform gravimetric and volumetric dispensing, capping/decapping, extraction, shaking, filtration, and centrifugation. Two robotic arms provide sample transportation without human assistance. Method Critical method performance attributes were characterized using spiked corn, milk and peanut butter containing aflatoxins, deoxynivalenol, fumonisins, ochratoxin A, HT-2 and T-2 toxins and zearalenone and certified reference materials. Prepared samples were analyzed by liquid chromatography mass spectrometry (LC-MS). Results Recoveries of spiked samples range 100–120% with RSD&lt;20% and the majority of measured values of certified reference materials are consistent with certified values within ±20%. Within- and between-batch variabilities of QC samples range 5–9% and 7–12% respectively. Conclusions Our workflow introduces a straightforward and automated sample preparation procedure for LC-MS-based multimycotoxin analysis. Further, it demonstrates how individual sample preparation devices, that are conventionally used off-line, can be integrated together. Highlights This study shows automated sample preparation will replace manual operations and significantly increase the degree of automation and standardization for sample preparation.

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