Comparative study of analytical methods for hexavalent chromium / Carlos L. Nazario in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. LXXXV (Année 1990)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. LXXXV (Année 1990) . - p. 212-224 Titre : Comparative study of analytical methods for hexavalent chromium Type de document : texte imprimé Auteurs : Carlos L. Nazario, Auteur ; Edward E. Menden, Auteur Année de publication : 1990 Article en page(s) : p. 212-224 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Determination of hexavalent chromium is essential for disposal of chromium containing waste into the environment,but current methods produce ambiguity in reported results. Using five concentration levels of Cr(III) and spiking with three concentrations of Cr(VI),determinations of Cr(VI) were made using EPA** solid waste methods 7195(Coprecipitation), 7196(Colorimetric-Diphenylcarbazide), and 7197(Chelation-Extraction). The data indicate limitations in quantifying Cr(VI) in Cr(III) matrices. The Coprecipitation method was shown to be inadequate in determining the presence of Cr(VI) in Cr(III) matrices. Chelation-Extraction was able to show that one Cr(III) solution was free of any Cr(VI)contamination. For the other Cr(III)solution, the method indicated a presence of Cr(VI) but was unable to quantify the amount. Colorimetric analysis proved to be the most reliable, consistent, and informative of all three methods. It confirmed the findings of the Chelation-Extraction method and,in addition, quantified the amount of Cr(VI) present in the Cr(III) solution. En ligne : https://drive.google.com/file/d/15rr1LaP7LDuImz9aft51fLzTfctEPZns/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=8661 [article]

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Problems associated with hexavalent chromium determination / Frank H. Rutland in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. LXXXV (Année 1990)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. LXXXV (Année 1990) . - p. 326-333 Titre : Problems associated with hexavalent chromium determination Type de document : texte imprimé Auteurs : Frank H. Rutland, Auteur ; Waldo E. Kallenberger, Auteur ; Edward E. Menden, Auteur ; Carlos L. Nazario, Auteur Année de publication : 1990 Article en page(s) : p. 326-333 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : The ability to demonstrate that industry products, waste materials and disposal sites are free of hexavalent chronium is of crucial regulatory importance to the leather tanning industry. This requires reliable techniques to extract and detect, without alteration, small quantities of Cr6 from complex sample matrices in the presence of a large excess of Cr3 as well as other potential interferents. EPA solid waste methods 7195 (coprecipitation), 7196 (colorimetric) and 7197 (chelation/extraction) are not entirely suitable results. This report examines a number of case histories where false-positive Cr6 results were reported in tannery-related materials by independent testing laboratories, and recommends procedures to be followed in order to avoid these problems. Method 7195 is not recommended for samples with a large excess of Cr3. Methods 7196 and 7197 can provide results given reasonable care and validation. En ligne : https://drive.google.com/file/d/17LtjK6tmzj20AbcupBryPXPMg7ltrFuT/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=8723 [article]

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