[Portable Fourier transform infrared spectroscopy method for determining hydrogen chloride in workplace air]

Objective: To establish a portable Fourier transform infrared spectroscopy (FTIR) method for determining hydrogen chloride in workplace air. Methods: In May 2025, the concentration of hydrogen chloride in the air was determined using a FTIR spectrometer within the characteristic infrared absorption wave number range of hydrogen chloride (2640 cm(-1) to 2840 cm(-1)). The technical parameters of the method were evaluated, and the results were compared with those obtained by ion chromatography. Results: The quantitative analysis model of FTIR had a concentration range of 3.03-12.13 mg/m(3), with a detection limit of 0.58 mg/m(3) and a quantification limit of 2.32 mg/m(3). The accuracy was 100.0% to 104.6%, while the intra-batch precision was 0.5% to 1.9% and the inter-batch precision was 0.4% to 2.0%. The results of the FTIR method and the ion chromatography method for the determination of hydrogen chloride showed no statistically significant difference (P>0.05). Using the measurement results at 20 ℃ as reference, the decline rates at 4 ℃ and 37 ℃ were-0.1% and 1.2%, respectively. Under relative humidity conditions of 50%, 40%, 30%, and 17%, the decline rates measured by the portable FTIR were 23.2%, 9.9%, 1.0%, and-4.6%, respectively. Conclusion: The FTIR method is suitable for rapid determination of hydrogen chloride gas concentrations in workplace air.