Determination of gaseous carbonyl compounds by their pentafluorophenyl hydrazones with gas chromatography/mass spectrometry

Abstract

A sensitive and reliable method has been developed for the simultaneous determination of 20 airborne carbonyl compounds in the C 1–C 10 range. The carbonyls were collected onto solid sorbent coated with pentafluorophenyl hydrazine (PFPH), followed by solvent extraction and gas chromatographic (GC)/mass spectrometric (MS) analysis of the PFPH derivatives. The sorbent is packed into two separate sections in a glass sampling tube. The two-section design allows convenient checking of collection efficiency and breakthrough. The sampling tube, with a coating amount of 971 nmol PFPH per 100 mg Tenax TA and operated at a sampling flow rate of 80 mL min −1, collects the 20 carbonyls with efficiencies above 95%. Hexane extracts the collected carbonyls in their PFPH derivatives in the sampling tube with better than 95% extraction efficiency. It is necessary to let the sampling tube sit at ambient temperature for 3 days before solvent extraction to ensure complete derivatization of the carbonyls. The limits of detection (LODs) of the tested carbonyls are in the range of 3.7–11.6 ng per sample. The method has been field-tested both in ambient environment and in an indoor environment from burning mosquito-repellent incense. Eighteen carbonyls were detected in the ambient air samples with the exception of o-tolualdehyde and m-tolualdehyde, while all the 20 target carbonyls were found in the incense smoke. Compare field test with classical DNPH–HPLC/UV method, good agreement exited between the two methods for lower molecular carbonyls but PFPH method is found to be a better analytical method for determination of high molecular weight carbonyls.