Comparison of several sorbents for continuous in situ derivatization and preconcentration of low-molecular mass aldehydes prior to liquid chromatography-tandem mass spectrometric determination in water samples.

A comparative study of six SPE conventional and non-conventional sorbent materials (silica RP-C18, LiChrolut EN, Amberlite XAD-2, C60 fullerene, multiwall carbon nanotubes and graphitized carbon black) was carried out for the in situ derivatization/preconcentration of eight aldehydes with 2,4-dinitrophenylhydrazine. Although two of the sorbents, LiChrolut EN and RP-C18, turned out to be the most suitable for ultratrace analysis of the aldehydes, LiChrolut EN showed higher capacity for 2,4-dinitrophenylhydrazine trapping (higher efficiency for the in situ derivatization reaction) and superior performance in terms of sensitivity (likely a result of its increased sample breakthrough volume). The LiChrolut EN-based method combined with LC-MS/MS allowed the determination of aldehydes over the linear range of 0.02-15 microg l(-1), with limits of detection at 6-24 ng l(-1) and precision of 3.2-7.2%. The method was applied to determine low-molecular mass aldehydes in water samples. These results indicate that the method proposed is a straightforward and sensitive tool for the determination of these aldehydes in water samples providing better results than those LC-MS/MS reported alternatives in terms of the limit of detection, sample requirements for analysis and cost.