Improved solid-phase extraction/micellar procedure for the derivatization/preconcentration of benzaldehyde and methyl derivatives from water samples

A simple, rapid and sensitive method has been developed for the determination of aromatic low-molecular mass aldehydes (LMMAs) such as benzaldehyde (BA) and methyl derivatives in water samples through the use of liquid chromatography-diode array detection (LC-DAD). The method is based on the continuous in situ derivatization of the aldehydes with 2,4-dinitrophenylhydrazine (DNPH) on a LiChrolut EN solid-phase extraction (SPE) column in the presence of sodium dodecyl sulfate (SDS) micelles. After elution, hydrazones were successfully separated on a RP-C18 column using a linear gradient mobile phase of acetonitrile (ACN)-water at 75-95% ACN for 10 min. Linearity was established over the concentration range 0.4-200 μg L-1 and limits of detection (LODs) from 120 to 200 ng L-1; the inter-day precision expressed as the relative standard deviation (RSD) of the aldehydes ranged from 3.0% to 3.5%. The method was successfully applied to the analysis of aromatic and aliphatic LMMAs in water samples with average recoveries ranging between 93.6% and 99.5%. The proposed method surpasses other chromatographic alternatives in terms of LODs, sample requirements for analysis and cost.