Two wet digestion methods for the determination of total arsenic in urine by digestion-atomic fluorescence spectrometry

Objective To compare the two digestion methods of ammonium persulfate and the mixed acid system of nitric acid, sulfuric acid, and perchloric acid in determining total arsenic in urine by digestion-atomic fluorescence spectrometry.

Methods Urine samples were digested by the mixed acid system of nitric acid, sulfuric acid, and perchloric acid and saturating ammonium persulfate at 310 ℃ for 1 hour, then thiourea-ascorbic acid was added to reduce the sample, and the samples were placed in the atomic fluorescence spectrometry analyzer for determination.

Results Within the range of 1.00-20.00 μg/L for the content of arsenic, the standard curve regression equation was y=106.587x-11.979, with a correlation coefficient of >0.999 0. The digestion method of the mixed acid system had a precision of 2.06%-3.03%, an average spike recovery of 101.2%-104.3%, and a detection limit of 0.012 μg/L. The saturating ammonium persulfate digestion method had a precision of 3.31%-4.05%, an average spike recovery of 97.9%-101.6%, and a detection limit of 0.006 μg/L.

Conclusion The accuracy and precision of both methods meet the requirements in Determination of arsenic in urine by hydride generation atomic fluorescence spectrometry(WS/T 474-2015), and the two methods are suitable for large-scale determination of total arsenic content in urine.