Sorption–Chromatographic Determination of Aniline, 4-Chloroaniline, and 2,5-Dichloroaniline in Air

Conditions were found for the chemisorption preconcentration of aniline, 4-chloroaniline, and 2,5-dichloroaniline from air using tubes packed with silica gel with immobilized 4-chloro-5,7-dinitrobenzofurazan and for the subsequent HPLC determination with diode-array detection. The maximum analyte recoveries (98, 90, and 75% for aniline, 4-chloroaniline, and 2,5-dichloroaniline, respectively) were achieved at a 2-cm thickness of the adsorbent layer (silica gel with a grain size of 0.1–0.3 mm impregnated with 3 wt % 4-chloro-5,7-dinitrobenzofurazan), an aspiration rate of 0.6–0.8 L/min, and an aspirated air volume of 10 L. Taking into account a tenfold preconcentration of analytes after the desorption, the detection limit for aniline is equal to 0.0007 mg/m³.