Dual cloud point extraction coupled with hydrodynamic-electrokinetic two-step injection followed by micellar electrokinetic chromatography for simultaneous determination of trace phenolic estrogens in water samples

Abstract

A dual cloud point extraction (dCPE) off-line enrichment procedure coupled with a hydrodynamic-electrokinetic two-step injection online enrichment technique was successfully developed for simultaneous preconcentration of trace phenolic estrogens (hexestrol, dienestrol, and diethylstilbestrol) in water samples followed by micellar electrokinetic chromatography (MEKC) analysis. Several parameters affecting the extraction and online injection conditions were optimized. Under optimal dCPE-two-step injection-MEKC conditions, detection limits of 7.9-8.9 ng/mL and good linearity in the range from 0.05 to 5 μg/mL with correlation coefficients R 2 ≥0.9990 were achieved. Satisfactory recoveries ranging from 83 to 108 % were obtained with lake and tap water spiked at 0.1 and 0.5 μg/mL, respectively, with relative standard deviations (n=6) of 1.3-3.1 %. This method was demonstrated to be convenient, rapid, cost-effective, and environmentally benign, and could be used as an alternative to existing methods for analyzing trace residues of phenolic estrogens in water samples.

Graphene oxide-based microspheres for the dispersive solid-phase extraction of non-steroidal estrogens from water samples

“…This phenomenon may be caused by different molecular status of the analytes. The pK a values for DES, DS and BPA were 7.34, 7.43 and 10.3, respectively [15,38]. For DES and DS, when sample pH was lower than 6.0, they were neutral molecular, the analytes showed high affinity with GO through hydrophobic interaction; when pH increased above 6.0, they were deprotonated and showed affinity with sample matrix.…”

“…5b, the extraction efficiency increased with the temperature increasing within the range of 20-40 • C and then decreased when the temperature was over 40 • C for DES and DS. This might be attributed to the heat unstability of phenolic hydroxyl groups in non-steroidal estrogens [15]. The phenolic hydroxyl group could be changed into quinone or other structure under high temperature.…”

“…Generally, the analytical methods for the determination of estrogens are conducted using high performance liquid chromatography (HPLC) [4][5][6][7][8][9][10][11], gas chromatography [12,13], capillary electrophoresis [14,15], ultra-high performance liquid chromatography [16] and biosensor [17,18]. Since the concentration of estrogens is very low in samples, most of the methods mentioned above need sample preparation, such as solid-phase microextraction (SPME) [5,9], solid-phase extraction [6], dynamic liquid-liquid-solid microextraction [7], cloud-point extraction [8,15], dispersive liquid-liquid microextraction (DLLME) [4] and liquid extraction [19,20]. For example, Guan et al [14] reported the preparation of multi-walled carbon nanotubes (MWCNTs)-OH functionalized magnetic particles and used the functionalized MWCNTs as adsorbents of dispersive solid-phase extraction (dSPE) for extracting estrogens.…”

Dispersive liquid‐liquid microextraction for four phenolic environmental estrogens in water samples followed by determination using capillary electrophoresis

“…For examples, liquid-liquid extraction [17,23] SPE [24,25], solid-phase microextraction (SPME) [26,27], stir bar sorptive extraction [28] and cloud-point extraction (CPE) [29] have been reported for estrogens. However, the classical extraction methods, liquidliquid extraction and SPE, require large volumes of organic solvents and long preparation time.…”

Thermosensitive molecularly imprinted polymers on porous carriers: Preparation, characterization and properties as novel adsorbents for bisphenol A

“…Phenolic environmental estrogens (PEEs) have received considerable concerns in the field of pollution monitoring and remediation, which may change the function of the endocrine systems and consequently elicit negative health effects [1,2]. Bisphenol A (BPA), one of PEEs, has been widely used as raw material of plastics and resins, antioxidants and polymerization inhibitors [3,4].…”