Determination of volatile organic compounds in water by headspace solid-phase microextraction gas chromatography coupled to tandem mass spectrometry with triple quadrupole analyzer

In the present work, a rapid method with little sample handling has been developed for determination of 23 selected volatile organic compounds in environmental and wastewater samples. The method is based on headspace solid-phase microextraction (SPME) followed by gas chromatography coupled to tandem mass spectrometry (GC–MS/MS) determination using triple quadrupole analyzer (QqQ) in electron ionization mode. The best conditions for extraction were optimised with a factorial design taking into account the interaction between different parameters and not only individual effects of variables. In the optimized procedure, 4 mL of water sample were extracted using a 10 mL vial and adding 0.4 g NaCl (final NaCl content of 10%). An SPME extraction with carboxen/polydimethylsiloxane 75 μm fiber for 30 min at 50 °C (with 5 min of previous equilibration time) with magnetic stirring was applied. Chromatographic determination was carried out by GC–MS/MS working in Selected Reaction Monitoring (SRM) mode. For most analytes, two MS/MS transitions were acquired, although for a few compounds it was difficult to obtain characteristic abundant fragments. In those cases, a pseudo selected reaction monitoring (pseudo-SRM) with three ions was used instead. The intensity ratio between quantitation (Q) and confirmation (q) signals was used as a confirmatory parameter.The method was validated by means of recovery experiments (n = 6) spiking mineral water samples at three concentration levels (0.1, 5 and 50 μg L−1). Recoveries between 70% and 120% were generally obtained with relative standard deviations (RSDs) lower than 20%.The developed method was applied to surface water and wastewater from a wastewater treatment plant and from a municipal solid-waste treatment plant. Several compounds, like chloroform, benzene, trichloroethylene, toluene, tetrachloroethylene, dibromochloromethane, xylenes and bromoform were detected and confirmed in all the samples analyzed.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Employing a statistical optimization improves results reducing experiments. ► Use of MS (QqQ) allows high sensitivity determination and improves identification capabilities. ► Using Q/q intensity ratios is a powerful tool to ensure compound identification. ► HS SPME GC–MS/MS method allows determination of VOCs in complex matrix water samples.