Enantiomeric profiling of chiral drugs from environmental solid matrices with the use of microwave assisted extraction and chiral LC-MSMS

Many pharmaceuticals and illicit drugs are chiral. Often these enantiomers interact with biological systems differently resulting in disparate metabolism, excretion and/or therapeutic or undesirable effects. It is established practice within the pharmaceutical industry to assess each enantiomer individually and, if economically viable and therapeutically necessary, to produce single enantiomeric formulas. However environmental analysis, and therefore any risk assessment associated with it, has often only focussed on whole drugs rather than individual enantiomers. Chiral analysis however allows the compound’s enantiomers to be assessed individually, resulting in a deeper understanding of a) the risks to organisms from the drugs and b) the impacts of organisms on the enantiomeric profile of those drugs. This microbial impact, through both ad hoc and directed transformation e.g. in activated sludge, could in turn have implications for both the organisms downstream and/or the microbiological populations associated with this transformation.
Aquatic environments are dynamic and complex systems, compounds may adsorb and desorb to solid matrices within the liquid fraction whilst degrading and transforming. The concentration of pharmaceuticals in water sources has long been reported, however methods to extract drugs from solid matrices have been slower to develop. Yet excluding any compounds adsorbed onto particles or settled out into sediments will leave an incomplete picture of the drugs which organisms will be exposed to, also possibly skewing the accepted composition of drugs within aquatic environments to those which are more inclined to stay in solute.
This project is the first to the author’s knowledge to report a method for the enantiomeric profiling of pharmaceuticals and illicit drugs extracted from environmental solids. The authors have included a variety of pharmaceuticals and illicit drugs as well as many of the metabolites associated with the drugs. Among the studied chiral drugs are: beta-blockers, antidepressants, anti-inflammatory drugs, amphetamines and designer drugs. Several matrices are compared to give an indication of matrix effects on the method in question.
The poster will detail the method development and validation of the extraction method which employed Microwave Assisted Extraction (MAE) using a MARSXpress Microwave (CEM, UK) and Solid Phase Extraction (SPE) using 30µm Oasis HLB cartridges (Waters, Manchester, UK) for sample concentration. The analysis was carried out using HPLC-MS/MS performed on Waters ACQUITY UPLCTM system (Waters, Manchester, UK) and a Xevo TQD Triple Quadrupole Mass Spectrometer (Waters, Manchester, UK), equipped with an electrospray ionisation source. The chiral separation was carried out on a Chiral-Chirobiotic column, 250 x 4.6 mm, I.D. 5µm (Sigma-Aldrich, UK) and 20 x 4.0 mm, I.D. 5 µm guard column (Sigma-Aldrich, UK).
The technique discussed will allow for a more comprehensive understanding of the presence of drugs in aquatic environments and will provide information on the dynamics of transformation and adsorption if used in conjunction with temporal and/or spatial sampling or microcosm studies.