Identification of VOCs responsibles for odours in wastewater by HS-SPME with GC-EI-Q-Orbitrap

Abstract

This study evaluates the capabilities of identification of unknown compounds and the optimisation of the extraction technique for odour-causing volatile organic compounds (VOCs) in wastewater samples based on headspace solid-phase microextraction (HS-SPME). The water samples were analysed by gas chromatography coupled to mass spectrometry using a Q-Orbitrap mass analyser. A total of 3 wastewater samples from 3 WWTPs (Castellón: influent; Benicasim: outlet of the primary settling tank; Villarreal: outlet of the biological reactor) were mixed and used as a model for the development and optimisation of the method. Additionally, a total number of 16 samples were collected every 15 days from the three WWTP. In order to optimise the HS-SPME method, a multivariate approach using the response surface method was used obtaining optimum values of 3 mL of sample, 45ºC as extraction temperature and 0.6 g of NaCl (20% in the sample). To ensure reliable identification, the parameters of comprehensive score greater than 80, RSI>700 and ΔRI≤50 were established as reference values. As a result, 67 compounds could be identified, from which 12 were responsible for odours.