Critical appraisal of analytical procedures for the determination of CR(VI) in dyed leathers by 1,5 diphenylcarbazide spectrophotometry after sample dilutin or color removal / J. Scancar in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CII, N° 3 (03/2007)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CII, N° 3 (03/2007) . - p. 85-92 Titre : Critical appraisal of analytical procedures for the determination of CR(VI) in dyed leathers by 1,5 diphenylcarbazide spectrophotometry after sample dilutin or color removal Type de document : texte imprimé Auteurs : J. Scancar, Auteur ; R. Milacic, Auteur ; N. Bukovec, Auteur ; T. Osterman, Auteur Année de publication : 2007 Article en page(s) : p. 85-92 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Colored chemical species in leather extracts may contribute to the measurement signal in spectrophotometric determination of Cr(VI), resulting in false positive Cr(VI) concentrations. In the present work the efficiency of sample dilution, or color removal by the use of RP C18 columns and columns filled with florisil, to reduce color interferences prior to spectrophotometric determinations of Cr(VI) in dyed leathers were evaluated. Limits of detections were 2.5 mg kg-1 Cr(VI) when samples were diluted (1:5) and 0.5 mg kg-1 Cr(VI) after color removal by RP C18 or florisil. In all procedures applied repeatability and reproducibility of measurements were better than ± 5 %. The accuracy of the 1,5 diphenylcarbazide spectrophotometric determination of Cr(VI) was tested by analysis of the certified reference material CRM 544, Cr(VI) in lyophilized solution. By spiking leather extracts it was experimentally proven that the use of decolorizing agents did not change Cr(VI) speciation. The experimental data also indicated that in some of the leather extracts analyzed colored species caused severe positive interference effects that could not be reduced by dilution or the use of RP C18. Florisil was found to be an efficient decolorizing agent and enabled accurate and reliable determination of Cr(VI) in dyed leathers by 1,5 diphenylcarbazide spectrophotometry. En ligne : https://drive.google.com/file/d/1wEa6iB2_-GBRgPmRvj5TyguS-TjxINaQ/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=3364 [article]

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Fractionation of Cr and determination of Cr(VI) in blue shavings / R. Milacic in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), LXXXVII, N° 6 (06/1992)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > LXXXVII, N° 6 (06/1992) . - p. 221-232 Titre : Fractionation of Cr and determination of Cr(VI) in blue shavings Type de document : texte imprimé Auteurs : R. Milacic, Auteur ; Janez Stupar, Auteur ; Nevenka Kozuh, Auteur Année de publication : 1992 Article en page(s) : p. 221-232 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Blue shavings are a protein-based matrix with a high content of chromium(III) salts and organic polymers.If they contain excessive amounts of chromium(VI) they could be a potentially hazardous waste in the environment.Fractionation of chromium in blue shavings was studied by employing various sequential extraction procedures to determine the water soluble,exchangeable,organically bound,carbonate,crystalline, hydroxide and sulphide fractions.Chromium(VI) was determined in the phosphate buffer extractable(pH=6.5-7.0) fraction. Results obtained by several analytical techniques indicate limitations in the determination of Cr(VI).Ion-pairing reversed phase HPLC combined with flame or electrothermal AAS was found to be affected by severe matrix effects due to organic polymers in blue shavings and high salt concentrations in the buffer and extractant solutions.Chelating ion-exchange and ion-exchange chromatography combined with flame AAS detection gave over-estimated results due to inefficient retention of inert Cr(III) complexes.Spectrophotometry(addition of diphenylcarbazide reagent to the analyte prior to acidification) and extraction of Cr(VI)-HC1 complex into MIBK(277K) gave generally comparable and reliable results.The detection limit for the former technique was 2 ng cm(-3) and 15 ng cm(-3) for the latter.Our investigations indicate that over 90 percent of total chromium in blue shavings is in chemically inert form,approxymately 8 percent is extracted with Na4P2O7 while less than 0.003 percent exists in the toxic chromate form. En ligne : https://drive.google.com/file/d/1h15lkLO0eXXzNFGmURWR9ibxLcnpkr0t/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=8310 [article]

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Is spectrophotometry a reliable technique for determination of Cr(VI) in leather samples ? / R. Milacic in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 82, N° 3 (05-06/1998)

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 82, N° 3 (05-06/1998) . - p. 91-94 Titre : Is spectrophotometry a reliable technique for determination of Cr(VI) in leather samples ? Type de document : texte imprimé Auteurs : R. Milacic, Auteur ; J. Scancar, Auteur ; M. Urbanc, Auteur Année de publication : 1998 Article en page(s) : p. 91-94 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Chromium (VI) in coloured and non-coloured leather samples was determined by the standard spectrophotometric procedure DIN 53314 and also by extraction of the chromium (VI)-HC1 complex (277 K) into methyl isobutyl ketone (MIBK). Chromium (VI) was determined in the organic phase by flame atomic absorption spectrometry (FAAS). Both techniques were found to be sensitive enough for the determination of chromium (VI) in the samples analysed. The limit of detection for the spectrophotometry was 2.0 mg Cr(VI) kg-1 and for MIBK extraction 0.2 mg Cr(VI) kg-1 of leather. The interference effects of coloured species in leather extracts were investigated by employing the spectrophotometric technique. For this purpose diluted and non-diluted sample extracts were analysed. The results obtained were critically evaluated and compared to the MIBK extraction technique. The applicability of the spectrophotometric procedure for determination of chromium (VI) in coloured leather samples was estimated. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=7900 [article]

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