A modulation approach for covalent organic frameworks: Application to solid phase microextraction of phthalate esters

A modulation approach with 4-hydroxybenzhydrazide as the modulating agent was designed for constructing 2,4,6-triphenoxy-1,3,5-benzene-based covalent organic frameworks (COFs). The COFs materials were employed as solid phase microextraction (SPME) coatings for the extraction of phthalate esters (PAEs). Various experimental conditions including extraction temperature, extraction time, salt concentration, and desorption time were investigated and optimized. The introduction of modulating agent into the synthesis of fibers significantly enhanced the extraction efficiency towards PAEs. The linear range was 1-100 mu g L-1 and the detection limits in the range of 0.032-0.451 mu g L-1 were achieved with good linearity ranged from 0.9904 to 0.9970. Inter-batch and intra-batch relative standard deviations were in the ranges of 0.83-4.67% and 3.08-9.73%, respectively. Moreover, the developed coating fibers were used for the extraction of PAEs in water samples and satisfactory recoveries were achieved.