Sampling and Detection of Fluoro-substituted Nitrobenzenes in Air

A sampling column packed with silica gel was used for the collection and enrichment of fluoro-substituted nitrobenzenes in air and waste gas.The adsorbed analytes on the column were be desorbed with methanol and detected by gas chromatography using ECD detector.Working conditions of sampling flow rate,sampling time,total adsorbed amount and storage time in sampling column were optimized.Experimental results showed that in case sampling flow rate was less than 1.0 L·min-1 and the sampling period was in range of 20-40 min,the silica gel column showed good adsorption efficiency for the collection of total amount of 10 μg of fluoro-substituted nitrobenzenes.Using ultrasonic desorption technique,desorption efficiency of fluoro-substituted nitrobenzenes on the silica gel column was achieved to 90%-110%.RSDs of the method obtained were ranged in 0.4%-4.1%.The proposed method met with requirements for practical analysis.