The Influence of Foreign Ions on Determination and Speciation of Cr(VI) and Cr(III) from Water Samples

Abstract

The influence of various foreign cations and anions on the determination and speciation of Cr(VI) and Cr(III) in water samples was examined using flame atomic absorption spectrometry and UV/Vis spectrophotometry. Silica gel modified with Nb2O5 was evaluated as a solid phase extraction adsorbent for simultaneous speciation and concentration of chromium species. Measurement errors exceeding 10% were observed when certain cation concentrations exceeded specific thresholds: Mg2+ (>25 mg/L), Ni2+ (>100 mg/L), Fe3+ (>250 mg/L), Zn2+ (>500 mg/L), and Mn2+ (>1000 mg/L). Application to industrial wastewater and river samples showed that the content of almost all analyzed metals was below permitted discharge standards.