On-site selective capture of nitrophenols in waters based on tri-channel in-tip microextraction apparatus using molecularly imprinted monolith as adsorbent

Due to the high polarity, hydrophilicity and volatility, on-site selective separation and capture is vital in the accurate quantification of trace nitrophenols (NPs) in various water samples. In this connection, a new molec-ularly imprinted monolith (MIM) using 2,4-dinitrophenol (2,4-DNP) and 4-vinylpyridine/N,N'-methyl-enebisacrylamide as template and functional monomers, respectively, was prepared and acted as the adsorbent of home-made tri-channel in-tip microextraction apparatus (TIMA). The structure, morphology and pore property of the fabricated MIM was characterized with various analytical techniques. Results revealed that the MIM presented good specific recognition towards 2,4-DNP and its structural analogues. The recognition factor and capture capacity towards 2,4-DNP were as high as 3.6 and 15.1 mg/g, respectively, and the enrichment factors towards NPs varied from 254 to 319. Under the most favorable conditions, the proposed MIM/TIMA was employed to field capture of trace NPs in variety of environmental waters and followed by HPLC quantification. The limits of detection and RSDs for precision located in the ranges of 0.23-1.5 ng/L and 2.1-9.3 %, respectively. Recoveries with various spiked concentrations were in the range of 78.5-113 %. Furthermore, confirmation experiments were carried out to evaluate the accuracy and reliability of established approach. Satisfactory results well proved that the proposed MIM/MIMA is suitable for the on-site sample preparation of NPs at trace or ultra -trace levels in various water samples.

Automated summary

Selective separation and capture of trace nitrophenols in water samples is crucial for accurate quantification due to their high polarity, hydrophilicity, and volatility. This study developed a new molecularly imprinted monolith and used a homemade microextraction apparatus for adsorption. Results showed that the monolith exhibited specific recognition towards nitrophenols and successfully captured them. The proposed method was successfully applied for on-site sample preparation and quantification of trace nitrophenols in various water samples.