Abstract: Objective To optimize the determination of urinary mercury content by cold atomic absorption methodand standardize the expression of the determination results. Methods The urine sample was digested with potassium permanganate sulfate water bath,and stannous chloride was added online to reduce the mercury ions to elemental mercury,and then loaded into the light absorption cell with argon.The absorbance is proportional to the mercury content within a certain range and can be quantified by external standard method. Results The method for the determination of mercury in urine showed good linearity in the range of 0-5 μg/L,and the correlation coefficient was greater than 0.999 9. The detection limit and quantification limit of the method was 0.007 and 0.025 μg/L,respectively. The intra-assay precision of urine samples after being spiked with low,medium and high concentrations was 0.31%-0.89%,and the inter-assay precision was 1.40%-2.82%. The average recovery rate was 88.68%-90.15%. The determination results for the high and low levels of quality control samples are all within the reference range of the standard certificate. The unit of urine mercury test results should be converted to μmol/mol Cr（Creatinine） or μg/gCr. Conclusions In this paper,the cold atomic absorption analysis method for mercury in urine is optimized. After the sample is digested in a water bath at 80 ℃ for 90 minutes,stannous chloride is added online,the reaction is airtight,safe and efficient. The accuracy and precision of the method meet the standard requirements and can be used for the monitoring and evaluation of urinary mercury in the general population and occupational exposure population. The presentation of the urine mercury test results should meet the standard requirements,and the creatinine measurement method and sample source should be considered in the judgment of the results.

Key words: Urine mercury, Cold atomic absorption, Online stannous chloride, Results presentation