Selective determination of chromium (VI) in powdered milk infant formulas by electrothermal atomization atomic absorption spectrometry after ion exchange.
A previously developed method was adapted to the selective determination of hexavalent chromium in powdered milk infant formulas. The species in reconstituted milk was separated on an ion-exchange column, Chromabond NH2, and measured by electrothermal atomization atomic absorption spectrometry. The detection limit was 1.8 micrograms/L, and the linearity range under optimized conditions was 1.8-50.0 micrograms/L. The precision values were 4.1 and 6.5% for the analytical and overall procedures, respectively. The procedure was validated by the method of standard additions (5.0, 10.0, and 25.0 micrograms/L), and the recoveries were all > 93%. The developed method is sensitive, accurate, and precise for determination of Cr(VI) in powdered milks. It was applied to the determination of Cr(VI) in 20 commercial brands, i.e., 7 infant formulas, 5 follow-up milks, and 8 dietetic milks. The values found ranged from < 10 to 75 ng/g.
Soares
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University of Porto R. Aníbal Cunha, Faculty of Pharmacy, CEQUP, Portugal.
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D002852:Chromatography, Ion Exchange; D002857:Chromium / Q000032:analysis*; D005519:Food Preservation; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007225:Infant Food / Q000032:analysis*; D012680:Sensitivity and Specificity; D013054:Spectrophotometry, Atomic / Q000379:methods*
D002857:Chromium