COMPARISON AND VERIFICATION OF HEXAVALENT CHROMIUM DETECTION METHODS IN SOLID SAMPLES

This paper used two kinds of alkaline solution extraction/flame atomic absorption methods, Solid Waste-Determination of Hexavalent Chromium-by Alkaline Digestion/Flame Atomic Absorption Spectrophotometic (HJ 687—2014) and Soil and Sediment-Determination of Cr(Ⅵ)-Alkaline Digestion/Flame Atomic Absorption Spectrometry (HJ 1082—2019). The content of hexavalent chromium in solid waste and soil samples was measured and the experimental procedures, analytical method performance and uncertainty evaluation results of the two methods were compared and verified. The results showed that the detection limit of the HJ 687—2014 method was relatively higher, which was not suitable for the determination of soil with lower concentration. In HJ 1082—2019, it was required to configure the working curve according to the steps of sample preparation, which considered the influence of matrix interference. The detection limit of HJ 687—2014 was 0.28 mg/kg, the relative standard deviation was 0.69%~0.93%, and the sample recovery rate was 95.7%~97.2%. And the detection limit of HJ 1082—2019 was 0.17 mg/kg, the relative standard deviation was 0.6%~3.0%, and the sample recovery rate was 76.0%~83.1%. For the analysis of the same actual sample, the results of the two methods were similar. The detecting results of HJ 687—2014 and HJ 1082—2019 were (48.1±4.2), (46.6±5.4) mg/kg. After comparison, it was found that the main processes affecting the uncertainty of HJ 687—2014 and HJ 1082—2019 were curve fitting and sample digestion, respectively.