Sensitivity and quantitativeness of large-volume injection combined with liquid chromatography/high-resolution mass spectrometry for target screening analysis of emerging contaminants

Abstract

Solid phase extraction (SPE) has been widely used for pretreatment in target screening (TS) analysis. However, some compounds are difficult to recover by SPE or their recovery is unstable for environmental samples. In this study, we tested large-volume injection (LVI) without SPE for TS analysis of 103 compounds listed by the Ministry of the Environment (Japan)—so-called ‘items to be surveyed’—using liquid chromatography high-resolution mass spectrometry. We evaluated the limit of quantification (LOQ) by LVI and compared this LOQ with the LOQ by SPE pretreatment using a hydrophilic-lipophilic balance (HLB) combined with activated carbon, which was found previously to afford the best SPE cartridges for target compounds recovery. The LOQ generally decreased as the injection volume increased, and the LOQ was at least 250 times lower for a 500-μL injection than for a 2-μL injection for half of the compounds. LVI provided LOQs lower than the predicted no effect concentration for more compounds than the SPE method. The average matrix effect (ME) by LVI was in the range 70%–130% for 69 out of 97 compounds. The ME was higher or lower for some of the remaining compounds, but the ME was in the range 10%–1000% for all 18 water samples for 84 of the 97 compounds. Comparing the ME by LVI and the recovery ratio by the SPE method showed that LVI achieved more accurate quantitation than the SPE method for a larger number of compounds. Therefore, LVI provides better sensitivity and quantitativeness than the SPE method using HLB and activated carbon for TS analysis of as many ‘items to be surveyed’ as possible.