Development of in-situ suspended aggregate microextraction and multi steps stacking-capillary electrophoresis of targeted micropollutants

Abstract

Micro-pollutants are chemical and biological contaminants which are present in trace amounts in water bodies. A new sample pre-concentration technique known as in-situ suspended aggregate micro-extraction (iSAME) was used for the extraction of targeted environmental micro-pollutant in river waters samples. Extracts of indomethacin, diclofenac and ibuprofen by iSAME were analyzed using the multi-step field enhancement sample injection (FESI)-sweepingmicelle to solvent stacking (MSS) capillary electrophoresis (CE). The iSAME was optimized in terms of surfactants selection and concentration, temperature and extraction time. The FESI was carried out by creating a buffer zone to increase the sample load to enhance the signal. Sample was introduced into a 56 cm, 1% polydiallydimethyl ammonium chloride (PDDAC) coated capillary at -10 kV, and the sweeping used 15 mM hexadecyltrimethyl ammonium bromide (CTAB) as surfactant injected at 10 kV and MSS with 60% methanol injected at 50 mbar for 6 second. A combined surfactant of 10 mM CTAB with 25 mM 5-sulfosalicylic acid dihydrate (SSA) was found to give iSAME extraction efficiencies of 73.16, 77.93, and 83.81% for ibuprofen, diclofenac and indomethacine, respectively. Reversal of electro-osmotic flow (EOF) and migration order were recorded with the coated capillary. The limit of detection ranged from 0.011 to 1.148 µg/mL for standard solutions in FESI-Sweep-MSS. The sensitivity enhancement factors (SEF) of 727-898 were achieved by FESI-Sweep-MSS. The developed method was successfully applied for the detection of targeted pharmaceuticals in river water at four sampling stations. The quantification for the spike river water sample was performed by st a n d a r d calibration method. The recoveries in spiked river water sample ranged from 13% to 79 % for four assays with RSD of 0.81, 0.96 and 1.1 for ibuprofen, indomethacin, and diclofenac, respectively. The iSAME and multistep FESI-Sweep-MSS was successfully developed for the analysis of standard pharmaceuticals solution. The low recoveries of analytes in river water sample could be attributed to the high suspended solid present in the real river water sample which interfered with iSAME steps.