Carrier-mediated hollow fiber liquid-phase microextraction for preconcentration followed by spectrophotometric determination of amoxicillin

Preconcentration followed by ultraviolet spectrophotometric determination of amoxicillin (Amox) in pharmaceuticals and water samples by using a three-phase hollow fiber microextraction technique based on carrier-mediated transport has been presented. Amox was extracted from an aqueous solution (source phase) at pH 9.0 into 1-octanol containing 5% (w/v) Aliquat-336 impregnated in the pores of a hollow fiber. It was then back-extracted into NaCl solution (pH = 4.0) which was already positioned as the receiving phase inside the lumen of the hollow fiber. The extraction took place due to the concentration gradient of the counterion between the source and the receiving phases. Under the optimized conditions, an enrichment factor of 240 and a limit of detection of 0.2 μmol L−1 were obtained. The calibration curve was linear (R2 = 0.9967) in the concentration range of 0.5–10.0 µmol L−1 Amox. The interday relative standard deviation (n = 9) and the intraday relative standard deviation (n = 3) for 1.0 × 10−6 mol L−1 Amox solution were 7.3 and 6.4%, respectively.