A specific, highly enriching and “green” method for hollow fiber liquid phase microextraction of ionizable pharmaceuticals from fish tissue

Abstract

Ionizable pharmaceuticals are a class of emerging contaminants that pose a challenge to analytical chemistry due to their low environmental concentrations. To measure such low concentrations in organism tissue, e.g. fish muscle, specific extraction techniques minimizing co-extraction and interference alongside providing high enrichment of the compounds are needed. In this study we present a technique using hollow fiber liquid phase microextraction which is selective and highly enriching due to a pH gradient across a selective membrane, trapping ions in the extract. Microextraction minimizes the use of organic solvents, thereby making the technique “green”. We used high volume pharmaceuticals for method development, specifically, the weak acids ketoprofen, naproxen, diclofenac and ibuprofen, and the weak bases fluoxetine and sertraline. Lyophilized tissue extraction gave higher enrichment than fresh tissue extraction and concentration enrichment factors ranged from 1900 to 3000 times. Method detection limits with the analysis instruments used in this study were for ketoprofen, 0.23 ng g⁻¹ fish tissue; naproxen, 0.32 ng g⁻¹ fish tissue; diclofenac, 0.12 ng g⁻¹ fish tissue; ibuprofen, 0.34 ng g⁻¹ fish tissue; fluoxetine, 13 ng g⁻¹ fish tissue and sertraline, 23 ng g⁻¹ fish tissue. All analytes were successfully detected in tissue from fish exposed live via spiked water. The resulting extraction parameters shown in this study suggest the developed technique to be a useful work up method for extensive environmental data collection as well as for toxicokinetic studies.