Development, validation and comparison of two microextraction techniques for the rapid and sensitive determination of pregabalin in urine and pharmaceutical formulations after ethyl chloroformate derivatization followed by gas chromatography-mass spectrometric analysis

The present article reports first time the use of solid-phase microextraction (SPME) and dispersive liquid-liquid microextraction (DLLME) to extract pregabalin (PRG) from urine and pharmaceutical formulations followed by GC-MS analysis after ethyl chloroformate (ECF) derivatization. PRG is an antiepileptic and analgesic drug, which is a structural analogue of gamma-amino-butyric acid (GABA). It is approved by Food and Drug Administration (FDA) for the treatment of central nervous system (CNS) disorders and neuropathic pain. Initially PRG was derivatized with ECF in the presence of pyridine at room temperature for 30s. Experimental parameters were investigated for derivatization, SPME and DLLME conditions. The limit of detection (LOD) and limit of quantitation (LOQ) were found to be 0.019 mu g/ml and 0.063 mu g/ml for SPME and 0.022 mu g/ml and 0.075 mu g/ml for DLLME respectively. The percentage recovery, in case of SPME was in the range of 83-98% while for DLLME it is in the range of 84-98%. The intra and inter-day precisions were found to be less than 6%. The developed methods after ECF derivatization were found to be simple, fast, efficient and inexpensive. DLLME has several advantages like lesser extraction time and cost effectiveness as compared to SPME. The developed methods may find wide application for the routine determination of PRG in biological as well as in quality control samples of pharmaceutical formulations. (C) 2012 Elsevier B.V. All rights reserved.