Determination of Lead in Milk by Graphite Furnace-Atomic Absorption Spectrometry After Direct Injection of Sample Dilluted with Triton X-100

Content of lead in the milk sample solution after diluted with 0.20 g·L^-1 Triton X-100 diluted solution (containing 0.20% nitric acid), was determined by graphite furnace-atomic absorption spectrometry under the optimized instrument working conditions. 0.20 g·L^-1 palladium nitrate solution as matrix modifier was added online, thus to remove matrix interference. A standard curve was made by using matrix matching standard solution series, and results obtained showed that linearity relationships between mass concentration of lead and the corresponding absorbance were kept in the ranges of 1.00-4.00 μg·L^-1 and 6.00-24.0 μg·L^-1, with detection limit (3s) of 1.90 μg·kg^-1. Recovery test to milk samples was made at 4 concentration levels, giving recoveries in the range of 97.2%-102%, and RSDs of the determined values (n=5) were ranged from 1.5% to 13%, meeting the requirements of appendix F in national standard GB/T 27404-2008.The proposed method was used in analyzing of 8 milk samples, with mass fraction of lead all less than the limit (0.05 mg·kg^-1) specified in the national standard GB 2762-2017, and the results of determination obtained had no significant difference with those of ICP-MS after microwave digestion given in GB 5009.268-2016.