Determination of 8 kinds of carboxylic acids in workplace air by ion chromatography
Objective To establish an ion chromatographic method for simultaneous determination of 8 kinds of carboxylic acids in workplace air.Methods The air samples in the workplace were collected by a silicone tube,desorbed with 10 ml pure water which was added to a water bath at 60℃ for 5 min and then sonicated for another 10 min.The absorption liquid was directly filtrated and separated by Dionex IonPac AS11-HC anion column,and detected by the suppressed conductivity detector.The qualitative and quantitative analyses were based on retention time and peak-area respectively.Results The method had the good linearity for the eight carboxylic acids,and the correlation coefficients were between 0.9992 and 0.9999.The detection limits were in the range of 0.006-0.3 μg/ml(with the injection volume being 25 μl).The minimum detectable concentration of the method ranged from 0.02 mg/m3 to 0.6 mg/m3 when the sampling volume was 4.5 L.The method had good reproducibility,with the relative standard deviations of 0.30％-4.8％.The recoveries of standard addition for simulated samples were 95.8％-105％.The average desorption efficiency of the silicone tube was above 95.7％.Formic acid and acetic acid samples could be stably stored at a temperature of 4 ℃ for 4 days,while samples of propionic acid,acrylic acid,methacrylic acid,chloroacetic acid,dichloroacetic acid and trichloroacetic acid could be stably stored at a temperature of 4 ℃ for 7 days.Conclusion The method is rapid,sensitive and accurate,and it is suitable for simultaneous determination of 8 kinds of carboxylic acids,namely,formic acid,acetic acid,propionic acid,acrylic acid,methacrylic acid,chloroacetic acid,dichloroacetic acid and trichloroacetic acid in workplace air.The detection results can be applied to assessing occupational exposure levels and classification control of the above-mentioned carboxylic acids.
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