Thallium: A Polluting Metal of New Generation. Its Voltammetric Determination in Herbal Medicines in Presence of Metal Interferences

The present paper reports a new application: the voltammetric determination in herbal medicines of ultra-trace thallium(I), in the presence of lead(II), tin(II) and antimony(III) as interfering metals, by square wave anodic stripping voltammetry (SWASV). A conventional three-electrodes voltammetric cell was employed with a stationary hanging mercury drop electrode (HMDE) as working electrode and a platinum electrode and an Ag|AgCl|KClsatd. electrode as auxiliary and reference electrodes, respectively. The supporting electrolyte was 0.5 mol L−1 ammonium citrate buffer pH 6.5 + 7.3·10−3 mol L−1 EDTA-Na2. The analytical procedure was verified by the analysis of the standard reference materials: spinach Leaves NIST-SRM 1570a and tomato leaves NIST-SRM 1573a from National Institute of Standards and Technology. Precision and trueness, expressed as relative standard deviation and relative error, respectively, were generally lower than 7% in all cases. Once set up on the standard reference materials, the analytical procedure was transferred and applied to herbal medicines samples—Taraxacun officinale weber, Eucalyptus globulus and Harpagophytum procumbens DC—sold on the market. A critical comparison with spectroscopic measurements is also discussed.

Download Full-text

Voltammetric Determination of Metals in Copper Alloys at Trace and Ultratrace Concentrations

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20031437 ◽

2003 ◽

Vol 68 (8) ◽

pp. 1437-1448 ◽

Cited By ~ 4

Author(s):

Clinio Locatelli ◽

Giancarlo Torsi

Keyword(s):

Standard Deviation ◽

Relative Standard Deviation ◽

Relative Error ◽

Analytical Procedure ◽

Copper Alloys ◽

Voltammetric Determination ◽

Standard Reference Materials ◽

Relative Standard ◽

Precision And Accuracy

The present work describes the analytical procedures for the voltammetric determination of Cu, Pb, Cd, Zn, Fe, Mn, Co, Ni, Sn, Sb and Bi in copper alloys. The possibility of determining simultaneously metal concentrations in the case of interference of the voltammetric signals due to the peak overlapping is also highlighted and discussed. The analytical procedure was verified by the analysis of the standard reference materials: commercial bronze A NIST-SRM 1115, gunmetal BCS-CRM 207/2, high tensile brass BCS-CRM 390. Precision and accuracy, expressed as relative standard deviation and relative error, respectively, were in all cases lower than 6%. The limits of detection for each element were also reported.

Download Full-text

Measurement of Voltammetric Peak Area and Resolution of Overlapping Peaks in the Simultaneous Determination of Copper, Lead, Cadmium, and Nickel in Environmental Matrix

Journal of AOAC International ◽

10.1093/jaoac/83.6.1321 ◽

2000 ◽

Vol 83 (6) ◽

pp. 1321-1326 ◽

Cited By ~ 1

Author(s):

Clinio Locatelli

Keyword(s):

Simultaneous Determination ◽

Analytical Procedure ◽

Supporting Electrolyte ◽

Differential Pulse ◽

Standard Reference Materials ◽

Experimental Conditions ◽

Relative Standard ◽

Resolution Of Overlapping Peaks ◽

Determination Of Copper

Abstract Peak area was used for the simultaneous determination of copper(II), lead(II), cadmium(II), and nickel(II) in environmental matrixes by differential pulse voltammetry. The voltammetric measurements were performed with a conventional 3-electrode cell and an ammonia–ammonium chloride buffer, pH 9.1, as the supporting electrolyte. The analytical procedure was verified first in aqueous reference solutions and later by analysis of the standard reference materials Estuarine Sediment BCR-CRM 277 and River Sediment BCR-CRM 320. The precision and accuracy of the method, expressed as the relative standard deviation and the relative error, respectively, were <5% in all cases; the detection limit for each element under the experimental conditions used was in the range 1–5 μg/L. In the case of mutual interference between neighboring elements, an analytical procedure is proposed that is based on the standard additions technique, which allows the resolution of the overlapping voltammetric peaks.

Download Full-text

Optimization of analytical procedures for the simultaneous voltammetric determination of total Hg(II) in presence of Cu(II) in environmental matrices

Open Chemistry ◽

10.2478/s11532-011-0138-z ◽

2012 ◽

Vol 10 (1) ◽

pp. 267-276 ◽

Cited By ~ 2

Author(s):

Dora Melucci ◽

Simona Montalbani ◽

Clinio Locatelli

Keyword(s):

Reference Materials ◽

Gold Electrode ◽

Analytical Procedure ◽

Sea Water ◽

Differential Pulse ◽

Voltammetric Determination ◽

Standard Reference Materials ◽

Environmental Matrices ◽

Simultaneous Voltammetric Determination

AbstractThe present work reports the critical comparison about the employment of three different supporting electrolytes (0.1 mol L−1 HClO4, 0.01 mol L−1 EDTA-Na2 + 0.06 mol L−1 NaCl + 2.0 mol L−1 HClO4 and 0.1 mol L−1 KSCN + 0.001 mol L−1 HClO4) and their instrumental and chemical optimisation for the simultaneous voltammetric determination of total mercury(II) and copper(II) in sediments and sea water at gold electrode, especially discussing the reciprocal interference problems.The differential pulse anodic stripping voltammetric (DPASV) measurements were carried out using a conventional three-electrode cell: a gold electrode (GE) as working electrode, a platinum wire and an Ag‖AgCl‖KClsat as auxiliary and reference electrodes, respectively.The analytical procedure was verified by the analysis of standard reference materials: Estuarine Sediment BCR-CRM 277, River Sediment BCR-CRM 320 and Mercury in Water NIST-SRM 1641d.Once set up on the standard reference materials, the analytical procedure was transferred and applied to sediments and sea waters sampled in a lagoon ecosystem connected with Adriatic Sea (Ravenna area, Italy).

Download Full-text

Electrochemical Behaviour of a Gold Film- Glassy Carbon Electrode for Determination of Chromium (VI)

10.20944/preprints202101.0382.v1 ◽

2021 ◽

Author(s):

Nevila Broli ◽

Loreta Vallja ◽

Majlinda Vasjari

Keyword(s):

Glassy Carbon Electrode ◽

Glassy Carbon ◽

Electrochemical Behaviour ◽

Supporting Electrolyte ◽

Anodic Stripping Voltammetry ◽

Carbon Electrode ◽

Modulation Amplitude ◽

Chromium Vi ◽

Relative Standard

A gold nanostructured film modified glassy carbon electrode (Aufilm/GCE) was developed for the determination of chromium (VI) in water sample. GCE was immersed into HAuCl4 solution (10-3M) and electrodeposition of thin gold layer was conducted at –0.4 V (vs Ag/AgCl) for 10 min. The strong affinity between Au and Cr species resulted with increasing of Cr (VI) signal, compared with the bare glassy carbon electrode. The electrodepositing time, type of supporting electrolyte, pH, the scan rate, modulation amplitude, and modulation time were optimized using differential pulse anodic stripping voltammetry (DP-ASV). The calibration graph using accumulation time of 120 s was linear from 10 to 120 µgL-1 with a sensitivity 1.3 x 10-2 µA/µgL-1. Under optimum experimental conditions, a good correlation coefficient R2=0.9971, and a low detection limit 5.5 µg/L Cr (VI) was obtained. The signal was reproducible with a relative standard deviation ±4.5 %. The developed Aufilm/GCE sensor was applied for the Cr (VI) determination of in sewage water samples.

Download Full-text

Determination of Background Levels of Lead and Cadmium in Raw Agricultural Crops by Using Differential Pulse Anodic Stripping Voltammetry

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/65.4.987 ◽

1982 ◽

Vol 65 (4) ◽

pp. 987-991 ◽

Cited By ~ 3

Author(s):

R Duane Satzger ◽

Charles S Clow ◽

Evelyn Bonnin ◽

Fred L Fricke

Keyword(s):

Anodic Stripping Voltammetry ◽

Stripping Voltammetry ◽

Differential Pulse ◽

Standard Reference Materials ◽

Agricultural Crop ◽

Lead And Cadmium ◽

Relative Standard ◽

Anodic Stripping ◽

Quantifiable Level

Abstract A method is described for the simultaneous determination of ultratrace levels of lead and cadmium in selected agricultural crop samples by differential pulse anodic stripping voltammetry. Samples are dry ashed at high temperature with H2SO4 as an ashing aid. Techniques are described to control the lead and cadmium blank levels of 2 ng and 0.4 ng, respectively. Typical relative standard deviations for the crop analyses are 13% at 100 ng/g and 25% at 10 ng/g for lead, and 5% at 100 ng/g and 10% at 10 ng/g for cadmium. The lowest quantifiable level, based on 3 g dry sample, is 2 ng/g for lead and 1 ng/g for cadmium. Recovery studies, precision studies, and analyses of NBS Standard Reference Materials demonstrate the accuracy and reproducibility of this technique. A summary of results for over 1700 crop samples is reported.

Download Full-text

Determination of acrylamide in dry feedstuff for dogs and cats

Acta Veterinaria Brno ◽

10.2754/avb201382020203 ◽

2013 ◽

Vol 82 (2) ◽

pp. 203-208 ◽

Cited By ~ 1

Author(s):

Helena Veselá ◽

Emanuel Šucman

Keyword(s):

Analytical Procedure ◽

Low Cost ◽

Stripping Voltammetry ◽

Standard Reference Materials ◽

Hanging Mercury Drop Electrode ◽

Analytical Technique ◽

Voltammetric Measurement ◽

Relative Standard ◽

Ultrasound Bath

Acrylamide is considered to be an endogenous contaminant of food and feedstuff. Attention is paid to the acrylamide content in human nutrition products; however, there is lack of data about its concentrations in feedstuff. The aim of this study was to use a newly developed adsorptive stripping voltammetry procedure for determination of acrylamide concentrations in five and three different kinds of dog and cat dry feedstuff, respectively. The applied analytical procedure consists of a solvent extraction in ultrasound bath, followed by voltammetric measurement at the hanging mercury drop electrode in ammonia buffer. The accuracy of the method was verified by use of standard reference materials. The range of acrylamide concentration found in samples of dry dog and cat feedstuff ranged from 106 to 358 μg/kg, and from 66 to 269 μg/kg, respectively. The precision of analyses expressed in form of the relative standard deviations ranged between 0.6–1.7%. The voltammetric procedure appears to be a reliable, sensitive, rapid and low-cost analytical technique for the determination of acrylamide in food and feedstuff. The concentrations of acrylamide found in feedstuff were relatively moderate but it is undoubtedly necessary to monitor its concentrations in future.

Download Full-text

Direct determination of calcium in milk by atomic absorption spectrometry using flow-injection analysis

Eclética Química ◽

10.1590/s0100-46702007000300004 ◽

2007 ◽

Vol 32 (3) ◽

pp. 25-30 ◽

Cited By ~ 3

Author(s):

M. B. Petrovich ◽

V. R. A. Filho ◽

J. A. G. Neto

Keyword(s):

Reference Materials ◽

Flow Injection ◽

Direct Determination ◽

Absorption Spectrometry ◽

Sample Volume ◽

Standard Reference Materials ◽

Injection System ◽

Relative Standard ◽

Flow Injection System ◽

Assisted Decomposition

A flow-injection system with sample and reagent addition by the synchronous merging zones approach for calcium determination in milk by flame AAS is proposed. Main parameters were optimized using a factorial design with central point. The optimum conditions were 2.5% (m/v) for La concentration, 8 mL min-1 for the carrier flow-rate, 20 cm for coiled reactor and 250 ìL for sample volume. Different sample preparation procedures were evaluated such as dilution in water or acid and microwave-assisted decomposition using concentrated or diluted acids. The optimized flow system was applied to determine Ca in eleven commercial milk samples and two standard reference materials diluted in water. Similar calcium levels were encountered comparing the results obtained by the proposed method (dilution in water) with those obtained using microwave-oven digestion. Results obtained in two standard reference materials were in agreement at 95% confidence level with those certified. Recoveries of spiked samples were in the 93% - 116% range. Relative standard deviation (n = 12) was < 5.4% and the sample throughput was 150 measurements per hour, corresponding to a consumption of 250 µL of sample and 6.25 mg La per determination.

Download Full-text

Employment of Peak Area as Instrumental Datum for Improving the Voltammetric Quantitative Analysis of Heavy Metals in Fresh and Sea Water in the Presence of Surfactants

Journal of AOAC International ◽

10.1093/jaoac/85.1.233 ◽

2002 ◽

Vol 85 (1) ◽

pp. 233-242 ◽

Cited By ~ 1

Author(s):

Clinio Locatelli

Keyword(s):

Heavy Metals ◽

Natural Waters ◽

Sea Water ◽

Anodic Stripping Voltammetry ◽

River Mouth ◽

Stripping Voltammetry ◽

Differential Pulse ◽

Standard Reference Materials ◽

Po River ◽

Relative Standard

Abstract Peak area instead of peak height is used for the simultaneous determination of Cu(II), Pb(II), Cd(II), and Zn(II) in fresh and sea water in the presence of anionic and cationic surfactants by differential pulse anodic stripping voltammetry. These species, if present, tend to make more irreversible the electrodic process of the metals. Because the employment of peak area for species having irreversible electrodic processes permits limits of detection about one or 2 orders of magnitude lower, this work shows the possibility of determining heavy metals at ultratrace level concentrations in the presence of surfactants, compounds which are always present in natural waters. The precision and accuracy of the analytical method were checked by the analysis of the standard reference materials (SRM) Fresh Water NIST-SRM 1643d, Sea Water BCR-CRM 403, and Estuarine Water BCR-CRM 505. The former, expressed as relative standard deviation (sr), and the latter, expressed as relative error (e), were satisfactory, being in all cases lower than 5%. The analytical procedure has been applied to fresh and sea water sampled in the Po river mouth area (Italy).

Download Full-text

Determination of Ultratrace Levels of Lead in Infant Formula by Isotope Dilution Inductively Coupled Plasma Mass Spectrometry

Journal of AOAC International ◽

10.1093/jaoac/76.6.1378 ◽

1993 ◽

Vol 76 (6) ◽

pp. 1378-1384 ◽

Cited By ~ 3

Author(s):

Joseph J Thompson

Keyword(s):

Mass Spectrometry ◽

Infant Formula ◽

Reference Materials ◽

Isotope Dilution ◽

Inductively Coupled Plasma ◽

Standard Reference Materials ◽

Inductively Coupled ◽

Relative Standard ◽

Plasma Mass Spectrometry

Abstract A simple method was developed for the accurate and precise determination of low- and sub-ppb (ng/g) concentrations of lead in infant formula by isotope dilution inductively coupled plasma mass spectrometry using ultrasonic nebulization. After addition of a known amount of 207Pb, samples were microwave digested and the ratio 207Pb/208Pb was measured in the digests. Agreement with certified values for lead in milk powder standard reference materials was good, and isotope dilution analysis using 206Pb yielded identical results for the standard reference materials. Lead concentrations determined for several infant nutritional products were verified by an independent method. Typically, relative standard deviations of <4% were obtained with this method for lead concentrations above 2 ppb. The recovery of 2 ng of lead from an aqueous standard carried through the microwave digestion was 104 ± 4%. Infant formula (containing 0.6 ppb lead) to which 0.4 ng of natural-abundance lead had been added, to simulate a formula containing 0.9 ppb lead, was analyzed by isotope dilution, and the result was 96 ± 18% of the theoretical value. Thus, differences of 0.3 ppb lead could be clearly distinguished, and the detection limit was estimated to be 0.1 ng lead per gram of infant formula. The keys to accuracy for this method are minimizing contamination and accurately determining the concentration of lead in the isotopically enriched standard.

Download Full-text

ICP-MS AND ICP-AES ANALYSIS OF PLANT REFERENCE MATERIALS

Industrial laboratory Diagnostics of materials ◽

10.26896/1028-6861-2019-85-6-11-24 ◽

2019 ◽

Vol 85 (6) ◽

pp. 11-24

Author(s):

I. V. Nikolaeva ◽

A. A. Kravchenko ◽

S. V. Palessky ◽

S. V. Nechepurenko ◽

D. V. Semenova

Keyword(s):

Reference Material ◽

Mass Spectrometer ◽

Reference Materials ◽

Atomic Emission ◽

Icp Ms ◽

Lithium Metaborate ◽

Relative Standard ◽

Microwave System ◽

Total Analysis ◽

Siberian Pine

Two methods — ICP-MS and ICP-AES are used for certification of the new reference material — needles of Siberian pine (NSP-1). Techniques of the analysis include decomposition of plant samples in two different ways: acid digestion in a microwave system MARS-5 and lithium metaborate fusion followed by ICP-MS and ICP-AES analysis of the solutions. Simultaneous determinations of all the elements were carried out in low, medium and high resolution using SF-mass-spectrometer ELEMENT and atomic-emission spectrometer IRIS Advantage with external calibrations and internal standards (In — ICP-MS, Sc —ICP-AES). Middle and high resolutions of ICP mass spectrometer were used for interference corrections. Data obtained by ICP-MS and ICP-AES with different decomposition techniques are in good agreement. The ICP-MS and ICP-AES techniques have been validated by the analysis of three plant reference materials: LB-1 (leaf of a birch), Tr-1 (grass mixture) and EK-1 (Canadian pondweed). These techniques were used for the determination of 38 elements in the new reference material NSP-1. Relative standard deviations for most of the determined elements were below 10%. Combination of ICP-MS and ICP-AES techniques for certification of the new reference material makes it possible to expand the set of elements to be determined and to reduce the total analysis time.

Download Full-text