Application of statistical experimental design to the optimisation of microextraction by packed sorbent for the analysis of nonsteroidal anti-inflammatory drugs in human urine by ultra-high pressure liquid chromatography

A new approach based on microextraction by packed sorbent (MEPS) and a reversed-phase ultra-high pressure liquid chromatography (UHPLC) method was developed and validated for the determination and quantification of nonsteroidal anti-inflammatory drugs (NSAIDs) (acetylsalicylic acid, ketoprofen, diclofenac, naproxen and ibuprofen) in human urine. The important factors that could influence the extraction were previously screened using the Plackett-Burman design approach. The optimal MEPS extraction conditions were obtained using C18 phase as a sorbent, small sample volume (20 mu L) and a short time period (approximately 5 min) for the entire sample preparation step. The analytes were separated on a core-shell column (Poroshell 120 EC-C18; 100 mm x 3.0 mm; 2.7 mu m) using a binary mobile phase composed of aqueous 0.1% trifluoroacetic acid and acetonitrile in the gradient elution mode (4.5 min of analysis time). The analytical method was fully validated based on linearity, limits of detection CLOD), limits of quantification (LOQ), inter- and intra-day precision and accuracy, and extraction yield. Under optimised conditions, excellent linearity (R-2 >0.9991), limits of detection (1.07-16.2 ng mL(-1)) and precision (0.503-9.15% RSD) were observed for the target drugs. The average absolute recoveries of the analysed compounds extracted from the urine samples were 89.4-107%. The proposed method was also applied to the analysis of NSAIDs in human urine. The new approach offers an attractive alternative for the analysis of selected drugs from urine samples, providing several advantages including fewer sample preparation steps, faster sample throughput and ease of performance compared to traditional methodologies. (C) 2013 Elsevier B.V. All rights reserved.