Nanostructured composite of polydopamine/diatomite–based biosilica to enhance the extraction of phthalate esters from aqueous samples

Abstract

This study is aimed at the facile synthesis of a nanostructured composite of diatomite–based biosilica (BS)/polydopamine (BS@PDA) for extraction and preconcentration of five important phthalic acid esters (PAEs) with a wide range of polarities from aqueous samples. During the self–polymerization of dopamine, the internal nanopores and external surfaces of the BS were thoroughly covered with a thin layer of PDA that considerably enhanced its active surface and selectivity for trace analysis. The structural properties of the composite were evaluated using TEM, EDX, SEM, FT–IR, and BET, and the successful synthesis was confirmed. The effects of key parameters affecting the quantitative extraction of analytes were optimized. The concentrated analytes were effectively eluted off the adsorbent using the ethyl acetate solvent and finally were analyzed by gas chromatography-mass spectrometry. Under optimal conditions, the calibration curves were linear in the range of 0.5–250 ng/mL (R2 = 0.9960–1.0000). The intra-day and inter-day relative standard deviations (n = 6) for the analytes were 4.0%–5.8% and 5.5%–6.5%, respectively. The limits of detection and limits of quantitation of the analytes were 0.05–0.07 ng/mL and 0.17 to 0.23 ng/mL, respectively. The acceptable results obtained after spiking the standard PAEs in real samples can put forward BS@PDA as a new candidate for extracting and concentrating the analytes in the medical dextrose solution, tap water, and bottled mineral water samples.