A comparison of chromate analyses by AA, UV-Vis spectrophotometric, and HPLC methods

摘要

In this study, three methods of analyzing aqueous chromate concentrations, a flame atomic absorption (AA) method, a UV-Vis spectrophotometric method, and an HPLC method, were tested for their precision and accuracy at pH 3, 5, 7, 9, and 11 and ionic strengths of 1, 3, 10, 30, 100 mM. The best precision and accuracy based on standard deviation from the mean and standard error from the true value were achieved by the UV-Vis method (4 and 2), followed by the HPLC method (5 and 6). The AA method produced the same precision compared to the HPLC method (5) but the least accuracy (30). The detection limits were 0.4, 0.05, and 0.16 mg/L, and the linear response ranges were 1, 2, and 3 orders of magnitude for the AA, UV-Vis and HPLC methods, respectively. No significant effect of pH or ionic strength was observed within the ranges tested. The results indicate that in combination with an autosampler, the HPLC method is an effective way to analyze aqueous chromate concentration in the range of 0.3 to 300 mg/L. References: 15