Acetone-activated polyimide electrospun nanofiber membrane for thin-film microextraction and thermal desorption-gas chromatography-mass spectrometric analysis of phenols in environmental water.

In this work, a polyimide nanofiber membrane was electrospun and applied as sorbent for thin film microextraction (TFME). After TFME of phenols in water samples, direct thermal desorption of the sorbent at 300°C followed by gas chromatography-mass spectrometric (TD-GC-MS) analysis was carried out. The extraction efficiency of TFME was enhanced by 6-12 times for phenols after activation with acetone. The positive effect of acetone activation was correlated to the increased hydrophilicity of the membrane. Extraction parameters, including mass of nanofiber membrane, pH value, NaCl concentration and extraction time, were optimized. Under optimal conditions, the LODs and LOQs for analysis of phenols in spiked purified water were 0.0006-0.008 and 0.002-0.025μgL(-1), respectively. The linearity range was more than two orders of magnitude (R>0.99). The RSDs of intra-batch and inter-batch were 4.3-7.4% and 2.7-10.6% (n=3). Finally the method was applied to real samples, including tap water, sea water, and waste water. These results indicate that the polyimide nanofiber membrane is a promising candidate as TFME sorbent for determination of polar analytes in water samples coupled with TD-GC-MS.