Workplace monitoring of oximes using 2,4-dinitrophenylhydrazine-coated silica gel cartridges and liquid chromatography Original Research Article

A liquid chromatographic (LC) method for the determination of oximes in air samples using pre-column derivatization with a hydrazine reagent has been developed. Air samples are drawn over a 2,4-dinitrophenylhydrazine (DNPH)-coated silica gel cartridge to form the corresponding hydrazones. The acid coating of the tubes and the flow rate of the air sample have been selected considering the chemical characteristics of the oximes to avoid Beckmann rearrangement or incomplete recovery. The hydrazones are separated by LC with UV/Vis detection at 365 nm. Calibration is performed externally using the stable hydrazone standards. The limit of quantification is 0.5 pmol absolute for 2-butanone oxime (corresponding to 15.0 ng/l in a 2 l air sample) and cyclohexanone oxime (corresponding to 19.5 ng/l in a 2 l air sample), respectively. Real samples from industrial workplaces have successfully been analysed using this method.