Liquid-phase microextraction for the determination of acidic drugs and beta-blockers in water samples

Abstract

Liquid-phase microextraction (LPME) is a relatively simple and inexpensive sample preparation technique. Different LPME modes were designed in this work: two-phase LPME for extraction of hydrophobic acidic drugs, three-phase LPME for extraction of ionizable hydrophobic I?-blockers, and carrier-mediated LPME for extraction of a highly hydrophilic I?-blocker, atenolol (that was unable to be extracted by three-phase LPME). Under optimized conditions, two-phase LPME exhibited good linearity over four orders of magnitude in the concentration range, 0.2-200 ppb, with r2 values >0.992 for most of the analytes. The RSD for these compounds were between 7.4-11.8%. The LODs for these drugs were in the range of 10-2 ppb with enrichment factor >74. Both three-phase and carrier-mediated LPME displayed good precision with less than 8 % RSD for selected I?-blockers except for propanolol (18%). Both LPME modes also showed good linearity with r2 values >0.996. Enrichment factors for various I?-blockers were found to be around 50-fold in three-phase LPME, while the LODs were between 2-16 ppb. Conversely, carrier-mediated LPME provided 2.5-fold of enrichment with LOD of 62.5 ppb for atenolol. Both methods gave excellent extraction recovery with relative recovery in the range 85.7 to 108.2% for water samples.