Headspace gas chromatography–mass spectrometry for rapid determination of halonitromethanes in tap and swimming pool water

Abstract

Halonitromethanes (HNMs) are one of the most cytotoxic and genotoxic classes found among the unregulated disinfection by-products formed by the reaction of chemical disinfectants with natural organic matter in water. Typical methods used to determine these compounds in water (mainly trichloronitromethane) are based on the Environmental Protection Agency (EPA) method 551.1 using liquid-liquid extraction. A fast and straightforward method for the determination of the nine HNMs in water has been developed using a static headspace (HS) coupled with gas chromatography-mass spectrometry (GC-MS). Important parameters controlling headspace extraction were optimised to obtain the highest sensitivity: 250 μL of methyl tert-butyl ether (as a chemical modifier) and 6 g of anhydrous sodium sulphate were added to the water sample; an oven temperature of 80 °C and an equilibration time of 20 min were also selected. The addition of a chemical modifier favoured the volatilisation of all HNMs, increasing their signals up to approximately four times. Under optimum conditions, the method developed provides limits of detection between 0.03 and 0.60 μg/L and a relative standard deviation of ~6.0%. The developed method was validated and then compared with the reference method EPA 551.1 for the analysis of tap and swimming pool water. A good agreement in the results was observed, which corroborated the good performance of the proposed HS-GC-MS method.

Determination of halonitromethanes and haloacetamides: An evaluation of sample preservation and analyte stability in drinking water

“…More recently, two analytical methods employing headspace sampling have been reported for the determination of nine HNMs in tap and swimming pool water [16,17], which are more sensitive than LLE but also require specialized headspace sampling equipment. Sample preservation is also critical for maintaining sample integrity in finished drinking water samples where a disinfectant residual may exist.…”

Determination of volatile chlorinated hydrocarbons in water samples by static headspace gas chromatography with electron capture detection

“…The so‐called salting‐out effect is commonly used to improve the release of organic volatile compounds from an aqueous sample matrix to its headspace. The salting‐out increases the ionic strength of the aqueous solution and, in this way, could decrease the solubility of target analytes; therefore, the vapor–liquid equilibrium system would be changed . For investigating the influence of ionic strength on the performance of static headspace, experiments were performed by adding different amounts of NaCl (0∼30%).…”

Effervescence-assisted spiral hollow-fibre liquid-phase microextraction of trihalomethanes, halonitromethanes, haloacetonitriles, and haloketones in drinking water

“…In addition, the extraction of volatile compounds in aqueous solutions can be enhanced by the presence of an organic modifier (Peña et al, 2004). Thus, the addition of a chemical modifier, i.e., methyl tertbutyl ether (MTBE), in the sample favours the volatilization of HNMs, thus obtaining four-fold increased signals when compared with the absence of a modifier (Chang and Urban, 2016;Montesinos and Gallego, 2012b). According to this criterion, the effects of two chemical modifiers (n-hexane and MTBE) on the efficiency of DBP extraction with HF-LPME were tested.…”