An efficient sample preparation method based on dispersive liquid–liquid microextraction associated with back extraction for trace determination of acidic pharmaceuticals

Abstract

Reduction of matrix effect seems to be a great challenge for the development of a practical method in bioanalysis. In this regard, a simple and efficient DLLME procedure along with a back-extraction step (DLLME-BE) was developed for the preconcentration of four common non-steroidal anti-inflammatory drugs (NSAIDs) in various biological fluid samples. Briefly, the analytes of interest were initially transferred into the extraction solvent followed by the back-extraction into an immiscible basic methanol (as an acceptor phase) for further preconcentration and clean-up. The main purpose of the work is reducing the matrix effect and sensitive determination of target molecules in the complex matrices. Following on, the separation and determination of the analytes were carried out using GC–MS (in-port derivatization) and HPLC-DAD instrument. The influential parameters affecting the DLLME-BE method were evaluated in detail and the best extraction conditions were established. Under the optimum conditions, low method detection limits in the range of 0.1–1.0 and 0.1–6.0 µg L−1 were obtained for GC–MS and HPLC-DAD analysis, respectively. Additionally, fair intra-day precisions of 2.7–14.5 and 2.8–7.8% as well as inter-day precisions of 3.9–14.5 and 3.5–8.1% were achieved for the GC–MS and HPLC-DAD analysis, respectively. Finally, the method was successfully applied for the determination of four common NSAIDs in different biological fluid samples. Keywords: Dispersive liquid–liquid microextraction, Back-extraction, Non-steroidal anti-inflammatory drugs, Gas chromatography, High performance liquid chromatography