To develop a solution absorption-high performance liquid chromatography method for the determination of dimethyl oxalate and diethyl oxalate in workplace air.

Air samples were collected by porous glass plate absorption tubes filled with the absorption liquid, separated by a C18 chromatographic column, and detected at the wavelength of 210 nm. The retention time was employed for qualitative analysis, while the peak area was utilized for quantitative analysis.

The concentration-signal response of dimethyl oxalate and diethyl oxalate demonstrated satisfactory linearity within the concentration range of 2 to 100 μg/mL. The results for dimethyl oxalate indicate a regression equation of y = 1 964.2x + 2 383.8 (r > 0.999). The limits of detection and quantitation were 0.28 μg/mL and 0.94 μg/mL, respectively. The intra-assay precision ranged from 0.50% to 5.77%, and the inter-assay precision ranged from 0.83% to 5.83%. The recovery rate of standard additions varied between 98.44% and 99.86%. For diethyl oxalate, the regression equation was y = 2 214.5x + 2 633.9 (r > 0.999). The limits of detection and quantitation were 0.53 μg/mL and 1.76 μg/mL, respectively. The intra-assay precision ranged from 0.68% to 6.40%, while the inter-assay precision ranged from 1.02% to 6.59%. The recovery rate of standard additions varied between 98.93% and 100.63%. Sampling efficiencies for both dimethyl oxalate and diethyl oxalate were 100%. The absorption capacity of dimethyl oxalate was measured at 37.97 mg per 5.0 mL of absorption solution, while that of diethyl oxalate was 24.97 mg per 5.0 mL of absorption solution. The samples can be stored at 4 °C for at least three days.

This method is accurate, reliable, fast, and convenient, and the analytical performance meets the relevant requirements, which indicate that it has good potential for application in safeguarding the health of people occupationally exposed to dimethyl oxalate and diethyl oxalate.