Cellulose paper sorptive extraction (CPSE): A simple and affordable microextraction method for analysis of basic drugs in blood as a proof of concept.

Aiming towards simplifying sample preparation procedure, the present work explores use of unmodified laboratory filter paper as sorbent for extraction of nine basic drugs (five antidepressants, four benzodiazepines, and ketamine) from human blood samples and their analysis by gas chromatography-mass spectrometry (GC-MS). The procedure termed as cellulose paper sorptive extraction (CPSE) is straightforward. It involves adsorption of target analytes from deproteinized diluted blood samples on the unmodified cellulose paper followed by elution into 2 mL of methanol. Multivariate optimization, consisting of Placket-Burman design (PBD) and central composite design (CCD), was used to screen and optimize significant factors for CPSE. The proposed method follows the principles of green analytical chemistry (GAC), as the unmodified filter paper used as the sorbent is inexpensive and biodegradable. The technique is easy to perform and requires only 2 mL of MeOH during the entire extraction procedure. Under the optimized conditions, the limit of detection and quantification for the target analytes were estimated to be in the range of 0.003-0.035 and 0.010-0.117 µg mL-1, respectively. In contrast, the relative standard deviations were consistently below 10 %. The calibration curves were linear in the range of 0.015-2 µg mL-1 with a coefficient of determination (R2) in the range of 0.995-0.999.Satisfactory recoveries ranging from 87 to 99 % was achieved. As proof of concept, the analysis of nine drugs in blood samples from the patients was performed to demonstrate the potential application of the proposed method.