Miniaturized sample preparation techniques using MCM-41-based materials in the analysis of selected non-steroidal anti-inflammatory and anti-depressant drugs

Abstract

New approaches in miniaturized sample preparation have been investigated involving the use of mesoporous silica materials as adsorbents. Mesoporous silica MCM-41 was successfully synthesized from rice husk ash as an active source of silica and a few mg of the material was enclosed within a cone-shaped membrane for solid phase membrane tip extraction (SPMTE). Four non-steroidal anti-inflammatory drugs (NSAIDs) namely ketoprofen, mefenamic acid, naproxen and diclofenac were selected as target analytes. Under the optimized conditions the proposed MCM-41- SPMTE method provides good limits of detection (LODs) for analytes in human urine samples in the range of 5.7 - 10.6 µg/L and relative analyte recoveries in the range of 81.4 - 108.1% that are comparable with those of conventional solid phase extraction (SPE) method. A simple microextraction technique utilizing a mixed matrix membrane (MMM) as the extraction medium has been successfully demonstrated. Thiol-functionalized MCM-41 adsorbent was immobilized in the cellulose triacetate polymer matrix through dispersion method to form a thiol-MCM- 41-MMM. Three NSAIDs namely diclofenac, mefenamic acid and ibuprofen were used as target analytes. The results showed good relative recoveries (85.9 - 106.7%) with relative standard deviation (RSDs) < 8% (n = 9), and low LODs (0.04 - 0.19 µg/L) for spiked river and tap water samples. The newly developed method is a simple, feasible, and cost effective and showed results that are comparable with conventional SPE. The use of MCM-41 magnetized with iron oxide particles (Fe3O4) in magnetic solid phase extraction (MSPE) method has been investigated. The developed Fe3O4-MCM-41-MSPE method was applied to the extraction of two antidepressant drugs (amitriptyline and chlorpromazine) in human urine and plasma samples prior to gas chromatography–mass spectrometry (GC–MS) analysis. Under the optimized conditions, the results provided good relative recoveries (86.1 - 115.4%), good reproducibility with relative standard deviation (RSDs) < 10% (n = 5) and low LODs for both spiked urine (0.015 - 0.017 µg/L) and plasma (0.020 - 0.028 µg/L) samples. This method proved to be rapid and efficient, for the multi-analysis of the drugs in biological samples. A novel procedure involving sonication-assisted emulsification microextraction (SAEM) followed by Fe3O4-MCM-41-MSPE prior to HPLC-UV has been developed for the analysis of anti-depressant drugs (amitriptyline, chlorpromazine and imipramine) from biological and water samples. In the SAEM procedure, 1-octanol and 3 min were selected as emulsification solvent and extraction time, respectively. Under the most favorable conditions, the method showed good limits of detection (as low as 0.04 µg/L) and reproducibility of extraction (RSDs < 10.6%, n = 3). The proposed methods provide alternative approaches in sample preparation through different microextraction methods to solve analytical problems that are not easily addressed by the individual procedure alone.