Development and application of diffusive gradients in thin-films for in situ sampling of the bitterest chemical – denatonium benzoate in waters

In situ measurement of an emerging persistent, mobile and toxic (PMT) substance - Melamine and related triazines in waters by diffusive gradient in thin-films

“…The much smaller pore size of APA gels compared to agarose gels should have contributed to the lower DPA value of atrazine measured in this study (Zhang and Davison, 1999). This result is in accordance with our earlier findings for other chemicals using APA and agarose gels (Liu et al, 2021a;Liu et al, 2021b). The measurement for atrazine in this study was lower than that measured by Stroski et al (2018) (2.96 × 10 -6 cm 2 ⋅s -1 ) in a PA gel with 15% acrylamine monomer and 0.1% crosslinker (total monomer concentration, T%: 15.1%).…”

“…The uptake rates by the MCX gels ranged from 0.01 s -1 to 0.02 s -1 (a pseudo-first order model was assumed). They are about two orders of magnitudes higher than the ratios of diffusion coefficients of analytes through the diffusion layer over the square of its thickness (D/∆g 2 , 2 × 10 -4 s -1 -3 × 10 -4 s -1 ) (Dong et al, 2014), and are on the same order of magnitude as those of other organics chemicals in previous DGT studies (Liu et al, 2021a;Wei et al, 2019). This implies that the MCX gels exhibit strong and fast adsorption of the triazines that once they diffuse across the diffusive layer, they are immediately adsorbed onto the MCX gels without reverse-diffusion.…”

“…A standard DGT piston is manufactured from ABS resins and has been found to exhibit little adsorption of a wide range of chemicals (Guan et al, 2021;Zhang et al, 2019). APA diffusive gels have previously been demonstrated to exhibit much higher strength than agarose gels (Liu et al, 2021a) and resistance to biodegradation, therefore APA gel is preferable and tested first here. The results show that no significant adsorption of these triazines (less than 10%) occurred for APA gels, nylon filter membrane, and ABS pistons (Figure 1A).…”

“…Over the past decade, organic diffusive gradient in thin-films (DGT) technique, as an emerging passive sampling technique, has become increasingly popular for monitoring polar organic pollutants (Challis et al, 2016;Chen et al, 2012a;Chen et al, 2013;Liu et al, 2021a;Liu et al, 2021b). It belongs to the group of kinetic samplers which depend on a flux that is proportional to concentration (Williams, 2016).…”

Development and applications of diffusive gradients in thin films for monitoring pharmaceuticals in surface waters

“…DGT has been applied to the measurement of a broad range of organic pollutants, including pesticides ( Guibal et al, 2017 ), pharmaceuticals ( Challis et al, 2018 ; Chen et al, 2012 ; Chen et al, 2013 ; Xie et al, 2018 ; Xie et al, 2021 ; You et al, 2020 ; You et al, 2019 ), household and personal care products ( Chen et al, 2017 ), synthetic musks ( Ren et al, 2020 ), perfluoroalkyl substances ( Fang et al, 2021 ; Guan et al, 2018 ), endocrine-disrupting chemicals ( Chen et al, 2018 ; Guo et al, 2017b ; Guo et al, 2019 ), illicit drugs ( Guo et al, 2017a ; Zhang et al, 2018 ), organophosphate esters ( Wang et al, 2019 ), brominated flame retardants ( Feng et al, 2019 ), bisphenols ( Zheng et al, 2015 ), bitter agent ( Liu et al, 2021a ), and melamine ( Liu et al, 2021b ). Although these pioneering studies extended the use of DGT to monitor organic chemicals, model contaminants have remained limited.…”