Author/Editor		Milačič, R; Štupar, J; Kožuh, N; Korošin, J; Glazer, I
Title		Fractionation of Cr and determination of Cr(VI) in blue shavings
Type		članek
Source		JALCA
Vol. and No.		Letnik 87
Publication year		1992
Volume		str. 221-34
Language		eng
Abstract		Blue shavings are 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 potentially hazardous waste in the environment. Fractation of chromium in blue shavings was studied by employing various sequential extraction procedures to determine the water soluble, exchanghable, 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 extracant solutions. Chelating ion-exchange and ion-exchange chromatography combined with flame AAS detection gave over-estimated results due to inefficent retention of inert Cr(III) complexes. Spectrophotometry (addition of diphenylcarbazide reagent to the analyte prior to acidification) and extraction of Cr(VI)-HCl complex into MIBK (277 K) 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 forms, approximately 8 percent is extracted with Na4P2O7 while less than 0.003 percents exists in the toxic chromate form.
Descriptors		CHROMIUM HAZARDOUS WASTE ENVIRONMENTAL POLLUTANTS FRACTIONATION SPECTROPHOTOMETRY, ATOMIC ABSORPTION CHROMATOGRAPHY, ION EXCHANGE CHROMATOGRAPHY, HIGH PRESSURE LIQUID