AFS Determination of Arsenic in Sauer Kraut with Microwave Assisted Sample Digestion

The sample of sauer kraut was pretreated by slicing, crushing and homogenizing. A definite quantity of the homogeneous sample was taken and digested with conc. HNO3 and H2O2 firstly at 90 ℃ in a water bath for ca. 20 min, then after cooling, digested in the microwave digestor. After completion of digestion, the solution was cooled to room temperature and transferred to a 25 mL volumetric flask, 5 mL of mixed solution of 50 g·L-1 thiourea solution and 50 g·L-1 ascorbic acid solution were added, and then diluted to mark with water. Arsenic was determined in the sample solution by AFS under the optimized instrumental condition with addition of 14 g·L-1 KBH4 solution as reductant for generation of AsH3. Linear relationship between values of fluorescence intensity and mass concentration of arsenic was found in the range with 10 μg·L-1, with detection limit (3s/k) of 0.064 μg·L-1. Recovery and precision of the method were tested, giving results of recovery ranged from 89.0% to 102.5%, and RSD (n=6) of 1.7%.