An ionic-liquid-modified melamine-formaldehyde aerogel for in-tube solid-phase microextraction of estrogens followed by high performance liquid chromatography with diode array detection.

A combination between an ionic liquid and melamine-formaldehyde aerogel on the carbon fibers was developed for in-tube solid-phase microextraction of estrogens with high efficiency. The sorbent has a high enrichment capability for several estrogens. Scanning electron microscopy showed that the aerogel on the carbon fibers has a porous three-dimensional network structure. Several important parameters such as sampling volume, sampling rate, the concentration of organic solvent in sample, pH value of sample as well as desorption time were optimized towards estrogen targets. Comparing with melamine-formaldehyde aerogel coating, the coating gave higher extraction efficiency. Comparing with melamine-formaldehyde aerogel coating, the new coating displays higher extraction efficiency. An online analytical method of estrogens was established, by the combination between in-tube solid-phase microextraction and high performance liquid chromatography with diode array detector. Analytical figures of merit include low limits of detection (<0.20 μg L-1), wide linearity (0.15-20 μg L-1), high enrichment factors (1028-1256), good extraction repeatability (RSDs<2.5%) and satisfactory preparation repeatability (RSDs<10.5%). The method was applied to the determination of trace estrogen targets in plastic bottle, tap water and surface water. Graphical abstractSchematic representation of online combination between in-tube solid-phase microextraction and high performance liquid chromatography, based on an ionic liquid (IL)-modified melamine-formaldehyde (MF) aerogel coating on carbon fibers (CFs) in a polyether-etherketone (PEEK) tube.