Trace determination of low-molecular-mass substituted benzaldehydes in treated water using micro solid-phase extraction followed by liquid chromatography–mass spectrometric detection

• An environment-friendly method for analysis of aldehydes was developed.
• A novel sorbent, Telos™ ENV, for the derivatisation/extraction of aldehydes by using a μ-SPE system was proposed.
• Aromatic and aliphatic aldehydes were analysed as disinfection by-products in treated water by μ-SPE/LC–MS.
• For the first time, the occurrence of some substituted benzaldehydes in swimming pool water was reported.
• Method showed better features than reported alternatives for the analysis of aldehydes in water samples.

Aldehydes are a class of water disinfection by-products (DBPs) that are an object of special attention due to their high toxicity and carcinogenic effect. While aliphatic low-molecular-mass aldehydes (LMMAs) are often measured in waters, there is little information on the occurrence of aromatic LMMAs. This paper reports the development of a simple, rapid and sensitive method for the quantitative determination of six LMM substituted benzaldehydes (BAs) as DBPs in treated water. The method is based on the continuous in situ derivatisation/extraction of aldehydes on a Telos™ ENV μ-solid-phase extraction (μ-SPE) column impregnated with 2,4-dinitrophenylhydrazine (DNPH). After elution of the hydrazones with acetonitrile (ACN), the derivatives are analysed using liquid chromatography–mass spectrometry (LC–MS). Under optimum conditions, limits of detection (LODs) were obtained between 15 and 25 ng/L and the inter-day precision expressed as the relative standard deviation (RSD) ranged from 6.1% to 7.7%. Matrix effects were shown to be negligible by comparing the response factors (RFs) obtained in ultra-pure and treated waters. The proposed method is the first contribution developed for the analysis of LMM substituted BAs as DBPs in waters by LC–MS. Some of the aromatic LMMAs identified had not previously been reported for swimming pool water.