Micro liquid–liquid extraction combined with large-volume injection gas chromatography–mass spectrometry for the determination of haloacetaldehydes in treated water

Haloacetaldehydes (HAs) are becoming the most widespread disinfection by-products (DBPs) found in drinking water, besides trihalomethanes and haloacetic acids, generated by the interaction of chemical disinfectants with organic matter naturally present in water. Because of their high potential toxicity, HAs have currently received a singular attention, especially trichloroacetaldehyde (chloral hydrate, CH), the most common and abundant compound found in treated water. The aims of this study are focused on the miniaturisation of EPA Method 551.1, including some innovations such as the use of ethyl acetate as the extracting solvent, the enhancement of HAs stability in aqueous solutions by adjusting the pH ∼3.2 and the use of a large-volume sample injection (30 μL) coupled to programmed temperature vaporizer–gas chromatography–mass spectrometry to improve both sensitivity and selectivity. In optimised experimental conditions, the limits of detection for the 7 HAs studied ranged from 6 to 20 ng/L. Swimming pools have recently been recognized as an important source of exposure to DBPs and as a result, in this research for the first time, HAs have been determined in this type of water. Two HAs have been found in the analysed water: CH at concentrations between 1.2–38 and 53–340 μg/L and dichloroacetaldehyde between 0.07–4.0 and 1.8–23 μg/L in tap and swimming pool waters, respectively.

► Haloacetaldehydes analysis in treated water is reported for the first time.
► Direct MLLE method enables miniaturisation and adaptation of EPA Method 551.1. The PTV-based LVI using GC–MS provides a high degree of sensitivity.
► Acidification of water samples enhances haloacetaldehydes stability.