Multi-residue analysis of chiral and achiral trace organic contaminants in soil by accelerated solvent extraction and enantioselective liquid chromatography tandem-mass spectrometry.

Reported here is the first analytical methodology for the enantiomeric determination of chiral trace organic contaminants (TOrCs) in soil. Direct enantioselective separations were achieved on a Chirobiotic V2 column operated in polar ionic mode. Initial screening of vancomycin stationary phases found Chirobiotic V2 better suited for multi-residue separation of chiral TOrCs than Chirobiotic V, due to differences in the ligand linkage chemistry. Simultaneous enantioseparation of beta-blockers, beta-agonists, anti-depressants, anti-histamines and stimulants was achieved for the first time. This included the first separation of chlorpheniramine enantiomers with a method suitable for environmental analysis (i.e. coupled to MS). Investigation of mobile phase composition found that the concentration of liophilic ions had the greatest influence on enantioseparations and were of most importance during method development. The optimized method achieved simultaneous separation of salbutamol, propranolol, atenolol, amphetamine, chlorpheniramine and fluoxetine enantiomers with satisfactory resolution ( > 1.0). For completeness, such methods also need to support analysis of achiral TOrCs. Therefore, three achiral TOrCs (carbamazepine, carbamazepine 10,11 epoxide, and triclocarban) were included to demonstrate the method's suitability. Method recoveries for all analytes ranged from 76% to 122%, with method quantitation limits (MQLs) < 1 ng g-1. Application of the method to soil microcosm studies revealed stereoselective degradation of chiral TOrCs for the first time. For example, S(+)-amphetamine degraded at a faster rate than its corresponding enantiomer, leading to an enrichment of R(-)-amphetamine. Therefore, in order to better understand the risk posed from TOrCs on the terrestrial environment, chiral species need to be profiled at the enantiomeric level. This can now be achieved using the proposed methodology, whilst simultaneously profiling achiral TOrCs. Supplementary data and information are included at the end of the main article