Carbon paste electrode modified by trioctylamine(TOA) for determination of chromium(VI) in electronic materials

A carbon paste electrode modified by trioctylamine(TOA) was employed to determine Cr(Ⅵ) and the optimum experimental conditions were examined and identified.TOA/CPE can effectively accumulate Cr(Ⅵ) when the accumulation time was 10 min and the acid medium for accumulation was 0.15 mol/L H2SO4.A sensitive reduction peak at-0.45 V(vs.SCE) characteristic of trace Cr(Ⅵ) was detected by stripping voltammetry,and the reduction peak current exhibited a good linear response to Cr(Ⅵ) concentration in the range of 5.0×10-7～1.0×10-3 mol/L.Interference studies displayed that TOA/CPE had high selectivity for Cr(Ⅵ) and can accurately determine Cr(Ⅵ) in the presence of Cr(Ⅲ)(600-fold concentration),with a low detection limit at 3.4×10-9 mol/L(S/N=3). TOA/CPE was utilized to determine Cr(Ⅵ) in real electronic materials,and the experimental results were in good agreement with those by spectrophotometry.