Fully automated ionic liquid-based headspace single drop microextraction coupled to GC–MS/MS to determine musk fragrances in environmental water samples

Abstract

A fully automated ionic liquid-based headspace single drop microextraction (IL-HS-SDME) procedure has been developed for the first time to preconcentrate trace amounts of ten musk fragrances extensively used in personal care products (six polycyclic musks, three nitro musks and one polycyclic musk degradation product) from wastewater samples prior to analysis by gas chromatography and ion trap tandem mass spectrometry (GC–IT-MS/MS). Due to the low volatility of the ILs, a large internal diameter liner (3.4mm i.d.) was used to improve the ILs evaporation. Furthermore, a piece of glass wool was introduced into the liner to avoid the entrance of the ILs in the GC column and a guard column was used to prevent analytical column damages. The main factors influencing the IL-HS-SDME were optimized. For all species, the highest enrichments factors were achieved using 1μL of 1-octyl-3-methylimidazolium hexafluorophosphate ([OMIM][PF6]) ionic liquid exposed in the headspace of 10mL water samples containing 300gL−1 of NaCl and stirred at 750rpm and 60°C for 45min. All compounds were determined by direct injection GC–IT-MS/MS with a chromatographic time of 19min. Method detection limits were found in the low ngmL−1 range between 0.010ngmL−1 and 0.030ngmL−1 depending on the target analytes. Also, under optimized conditions, the method gave good levels of intra-day and inter-day repeatabilities in wastewater samples with relative standard deviations varying between 3% and 6% and 5% and 11%, respectively (n=3, 1ngmL−1). The applicability of the method was tested with different wastewater samples from influent and effluent urban wastewater treatment plants (WWTPs) and one potable treatment plant (PTP). The analysis of influent urban wastewater revealed the presence of galaxolide and tonalide at concentrations of between 2.10ngmL−1 and 0.29ngmL−1 and 0.32ngmL−1 and <MQL (Method Quantification Limit), respectively; while the remaining polycyclic musks concentrations were below the method quantification limits and two of the nitro musks (musk xylene and musk moskene) were not detected. The analysis of effluent urban wastewater showed a decrease in galaxolide and tonalide concentrations while the other target analytes were not detected. In waters from PTP only galaxolide was found at a concentration higher than MQL.