Determination Of Chromium In Urine Research Articles

Interlaboratory Comparison Investigations (ICIs) for human biomonitoring of chromium as part of the quality assurance programme under HBM4EU

BackgroundThe pan-European human biomonitoring initiative HBM4EU targets the harmonization of human biomonitoring (HBM) procedures and data for both environmental and occupational exposure, including chromium. The determination of chromium in urine (U-Cr), plasma (P-Cr) and whole blood (WB-Cr) is a common HBM application in employees occupationally exposed to chromium (VI) compounds. MethodsEuropean laboratories which have registered as candidate laboratories for chromium analysis within HBM4EU were invited to participate in a quality assurance/qualitycontrol (QA/QC) programme comprising interlaboratory comparison investigations (ICI) for the parameters U-Cr, P-Cr and WB-Cr. Participating laboratories received two samples of different concentrations in each of four rounds and were asked to analyse the samples using their standard analytical procedure. The data were evaluated by the Z-score approach and were reported to the participants after each round. ResultsThe majority of the 29 participating laboratories obtained satisfactory results, although low limits of quantification were required to quantify chromium concentrations in some of the ICI materials. The robust relative standard deviation of the participants’ results (study RSDR) obtained from all ICI runs ranged from 6 to 16 % for U-Cr, 7–18 % for P-Cr and 4–47 % for WB-Cr. The application of both inductively coupled plasma mass spectrometry (ICP-MS) and electrothermal atomic absorption spectrometry (EAAS) appeared appropriate for the determination of chromium in urine, plasma and whole blood with regard to occupational exposure levels. ConclusionThis QA/QC programme succeeded in establishing a network of laboratories with high analytical comparability and accuracy for the analysis of chromium across Europe.

Flow injection determination of total chromium in urine of occupationally exposed workers

An efficient and fast method has been developed to determine chromium in urine. It is based on an on-line ultrasound-assisted sample digestion procedure exploiting the stopped-flow mode, followed by flow injection chromium preconcentration using a minicolumn filled with a commercially available chelating resin (Chelite Che). The precision as repeatability (expressed as relative standard deviation, n = 11) was 1.4% at a 10 µg L−1 level. The recovery, based on analysis of spiked samples and solutions including urine matrix components, is quantitative. The detection limit was 0.5 µg L−1 when flame atomic absorption spectrometry was employed. The preconcentration factor is 42.6. The method was applied to the determination of chromium in urine of workers exposed to welding fumes.

Evaluation of electrodeposited tungsten chemical modifier for direct determination of chromium in urine by ETAAS

The direct determination of chromium in urine by electrothermal atomic absorption spectrometry (ETAAS) using graphite tubes modified with tungsten is proposed. Modification of the graphite is made by tungsten electrodeposition over the whole surface atomizer followed by carbide formation by heating the tube inside its own furnace. For tungsten electrocoating, the graphite tube and a platinum electrode were connected to a power supply as cathode and anode, respectively, and immersed in a solution containing 2 mg of W in 0.1% v/v HNO 3. Then, 5 V was applied between the electrodes during 20 min for tungsten electrodeposition over the whole atomizer. A SpectrAA 220 Varian atomic absorption spectrometer equipped with a deuterium background corrector was used throughout. Undiluted urine (20 μl) was delivered over the tungsten-treated tube and the chromium-integrated absorbance was measured after applying a suitable heating program with maximum pyrolysis at 1300 °C and atomization at 2500 °C. With electrodeposited tungsten modifier, the tube lifetime increased up to four times when compared to previous published methods for Cr determination in urine by ETAAS, reaching 800 firings. Method detection limit (3 S.D.) was 0.10 μg l −1, based on 10 integrated absorbance measurements of a urine sample with low Cr concentration. Two reference materials of urines (SRM 2670) from National Institute of Standards and Technology (NIST) were analyzed for method validation. For additional validation, results obtained from eight human urine samples were also analyzed in a spectrometer with Zeeman effect background correction.

Evaluation of electrodeposited tungsten chemical modifier for direct determination of chromium in urine by ETAAS

The direct determination of chromium in urine by electrothermal atomic absorption spectrometry (ETAAS) using graphite tubes modified with tungsten is proposed. Modification of the graphite is made by tungsten electrodeposition over the whole surface atomizer followed by carbide formation by heating the tube inside its own furnace. For tungsten electrocoating, the graphite tube and a platinum electrode were connected to a power supply as cathode and anode, respectively, and immersed in a solution containing 2 mg of W in 0.1% v/v HNO3. Then, 5 V was applied between the electrodes during 20 min for tungsten electrodeposition over the whole atomizer. A SpectrAA 220 Varian atomic absorption spectrometer equipped with a deuterium background corrector was used throughout. Undiluted urine (20 μl) was delivered over the tungsten-treated tube and the chromium-integrated absorbance was measured after applying a suitable heating program with maximum pyrolysis at 1300 °C and atomization at 2500 °C. With electrodeposited tungsten modifier, the tube lifetime increased up to four times when compared to previous published methods for Cr determination in urine by ETAAS, reaching 800 firings. Method detection limit (3 S.D.) was 0.10 μg l−1, based on 10 integrated absorbance measurements of a urine sample with low Cr concentration. Two reference materials of urines (SRM 2670) from National Institute of Standards and Technology (NIST) were analyzed for method validation. For additional validation, results obtained from eight human urine samples were also analyzed in a spectrometer with Zeeman effect background correction.

A critical evaluation of the graphite furnace conditions for the direct determination of chromium in urine

A critical study of the conditions for the direct determination of Cr in urine using GFAAS was carried out. A chemometric approach showed that the most important parameters that influence the efficiency of atomic Cr cloud formation were the atomization from the tube wall and the proper implementation of a pyrolysis step. The established procedure does not require any sample pre-treatment thus minimizing the risk of contamination. The Cr content in urine was determined using a calibration curve prepared with Cr spiked urine, easily correcting all potential matrix interferences. The heating program proposed took 68 s for a 30 μL urine sample. The procedure was applied for the determination of Cr in urine to investigate the absorption rate of Cr picolinate. The limit of detection and the characteristic mass for a 30 μL urine sample were 0.18 μg/L and 5.4 pg, respectively.

Determination of chromium in urine by electrothermal atomic absorption spectrometry using different chemical modifiers

The effects of the chemical modifiers Eu, Mg(NO 3 ) 2 , Pd, Eu-Pd and Ni and the use of longitudinally (with deuterium lamp background correction) and transversally (with Zeeman effect background correction) heated atomizers on the determination of chromium in urine samples were studied. When longitudinally heated atomizers were used, the background absorption was too high for the addition of most species, such as Mg(NO 3 ) 2 , Pd, Eu-Pd and Ni, rendering its use unsuitable for the determination of chromium in urine. The addition of Eu led to lower background signals. However, when longitudinally heated atomizers were used larger background absorption signals were observed on addition of a modifier. In contrast, with transversally heated atomizers the background absorption signals were low and were not influenced by the addition of a modifier, except when Mg(NO 3 ) 2 was added. In this case, the atomization signal shapes and the sensitivity were improved. The characteristic masses (m 0 ) and limits of detection (3σ) were 2.2 and 3.3 pg and 0.02 and 0.04 µg Cr l –1 for the longitudinally (using Eu as modifier) and transversally [using Mg(NO 3 ) 2 ] heated atomizers, respectively. Recovery studies and analysis of standard reference materials certified for chromium were performed to asses the accuracy. The results for the determination of chromium in real samples with both background correction procedures agreed well with a precision between 0.8 and 2.5%. Both procedures can be recommended and the choice will depend on instrument availability.

Systematic study of chromium determination in urine by graphite furnace atomic absorption spectrometry

The optimized measurement of Cr in urine samples using graphite furnace atomic absorption spectrometry, with a tungsten lamp and Zeeman-effect background correction is described. Sample dilution and slow hot injection were studied in an effort to improve the precision. Paramaters such as detection limit (0.08 μg l −1) and precision are reported. Based on this study, the Zeeman effect with slow hot injection of diluted sample is recommended. The method was evaluated by applying the conditions established to a certified reference urine. The method was applied to the determination of chromium in urine from healthy subjects and total parenteral nutrition patients.

Determination of chromium in urine by stable isotope dilution gas chromatography/mass spectrometry using lithium bis(trifluoroethyl)dithiocarbamate as a chelating agent

An isotope dilution gas chromatography/mass spectrometry method using lithium bis(trifluoroethyl)dithiocarbamate as a chelating agent is described for the determination of chromium in urine. A wet digestion procedure with HNO3-H2O2 is used for oxidizing the organic matter associated with urine samples. The isotope ratios are measured by selected ion monitoring in a general-purpose mass spectrometer using a 10-m fused silica capillary column. Memory effect, in sequential analyses of samples with different isotope ratios, was evaluated by preparing a series of synthetic mixtures and was found to be negligible. The accuracy of the method was verified by quantitation of chromium in the NIST freeze-dried urine reference material, SRM-2670, with a recommended chromium concentration of 13 micrograms/L in the normal level and certified chromium concentration of 85 +/- 6 micrograms/L in the elevated level.

Faster determination of chromium in urine by electrothermal atomisation atomic absorption spectrometry

Omission of the ashing stage in the determination of chromium in urine by electrothermal atomisation atomic absorption spectrometry (ETA-AAS) led to an increase in the background absorbance, but the values found were still within a range which a deuterium-arc background correction system is capable of correcting. Rapid three-stage furnace programmes omitting the ashing stage were developed for two systems: one for an instrument with deuterium-arc background correction using an uncoated tube and the other for a Zeeman-effect system using a pyrolytically coated tube. Cycle times of 53 and 70 s, respectively, were achieved for these methods which were developed for monitoring occupational exposure. Small matrix effects were overcome by adding a surfactant, Triton X-100, to the diluent. Samples and standards were diluted 1 + 1 with 1%V/V HNO3 and 0.25%V/V Triton X-100. Results obtained by the two methods agreed well (r= 0.997) and also with those obtained by a slower method using an ashing stage (r= 1.000). It was concluded that Zeeman-effect background correction was unnecessary for this determination and that faster and more precise results could be obtained with the simpler system using deuterium-arc background correction.

The problem of background correction in the determination of chromium in urine by atomic absorption spectrometry with electrothermal atomisation

A previously described positive interference in the determination of chromium in urine was ascribed to the failure of the deuterium arc background correction system to correct fully for background absorption. In this work, it is shown that the interference is dependent on the gain setting of the photomultiplier and on the atomisation temperature. At temperatures below 2400 °C the interference is absent, but on increasing the atomisation temperature from 2400 to 2700 °C the interference increases in severity. The interference is thought to be emission caused by chromium together with potassium and sodium in the matrix. Lowering the atomisation temperature to 2400 °C allows the determination of chromium in urine without significant interference using conventional deuterium arc background correction.

Determination of chromium in urine by probe electrothermal atomisation atomic emission spectrometry using a low-resolution monochromator

A low-resolution monochromator incorporating wavelength modulation background correction has been used to determine chromium in urine by ETA-AES. Chromium atomic emission was generated in a Perkin-Elmer HGA-72 graphite furnace equipped with a totally pyrolytic graphite tube and modified for probe atomisation. No significant spectral or chemical interferences from the urine matrix were encountered and samples were analysed against aqueous standards either directly or after 1 + 1 dilution with water. The accuracy of the procedure was confirmed by comparative analysis with two different ETA-AAS methods. The ETA-AES technique was used to measure chromium in urine down to a level of 0.3–0.5 ng ml–1. It is predicted that a lower detection limit can be achieved by optimisation of the spectrometer optical system.

Determination of Chromium in Urine by Flameless Atomic Absorption Spectrophotometry

Determination of Chromium in Urine by Flameless Atomic Absorption Spectrophotometry

Direct determination of chromium in urine by electrothermal atomic absorption spectrometry.

A simple, direct method for the determination of chromium levels in urine is described, electrothermal atomic absorption spectrometry having been used after the urine samples had been acidified. The optimal conditions at the ashing and atomization stages was determined. The detection limit of this method is 5 nmol/1, and the coefficient of variation (within day) is about 3% in the concentration range 20--400 nmol/1. Use of a low temperature asher with electrically excited oxygen before analysis gave results similar to those of the direct procedure. Good correlation was obtained from two other laboratories using different instruments and pretreatments.

Background correction and related problems in the determination of chromium in urine by graphite furnace atomic absorption spectrometry.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTBackground correction and related problems in the determination of chromium in urine by graphite furnace atomic absorption spectrometryBarbara E. Guthrie, Wayne R. Wolf, and Claude. VeillonCite this: Anal. Chem. 1978, 50, 13, 1900–1902Publication Date (Print):November 1, 1978Publication History Published online1 May 2002Published inissue 1 November 1978https://doi.org/10.1021/ac50035a043RIGHTS & PERMISSIONSArticle Views116Altmetric-Citations61LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (313 KB) Get e-Alerts Get e-Alerts

The direct determination of chromium in urine by selective volatilization with atom reservoir atomic absorption

The direct determination of chromium in urine by selective volatilization with atom reservoir atomic absorption