RESUMO
OBJECTIVE: To improve the pretreatment method for the detection of lead, manganese and their inorganic compounds in workplace air samples by flame atomic absorption spectrometry. METHODS: In this method, 20.0 mL of 1.0-2.0 mol/L nitric acid solution was used as the digestion solution to digest the microporous membrane sample at 140-160 ℃ to a volume of 0.5-1.0 mL. Samples were cooled and fixed to 10 mL and detected by flame atomic absorption spectrometry method. RESULTS: The lead detection had a good linear relationship in the range of 0.10-3.00 mg/L. The correlation coefficient was 0.999 5, the detection limit and the lower limit of quantification were 0.03 and 0.10 mg/L respectively(calculated by 3 and 10 times of standard deviation respectively). The minimum detection concentration was 0.004 mg/m~3, and the minimum quantitative concentration was 0.010 mg/m~3(collected by 75 L air calculation). The manganese detection had a good linear relationship in the range of 0.05-3.00 mg/L mass concentration. The correlation coefficient was 0.999 8, the detection limit and the lower limit of quantification were 0.015 and 0.05 mg/L respectively(calculated by 3 and 10 times of standard deviation respectively), the minimum detection concentration was 0.002 mg/m~3, and the minimum quantitative concentration was 0.007 mg/m~3(based on collection 75 L air calculation). The recovery rate of standard addition was 97.8%-99.6%, and the relative standard deviation within and between run were 0.4%-2.0% and 0.4%-1.7% respectively. CONCLUSION: The method is simple, the reagent consumption is small, the digestion temperature is low, the precision and accuracy are high. This method is suitable for widespread use.