Cationic gemini surfactant-resorcinol-aldehyde resin and its application in the extraction of endocrine disrupting compounds from food contacting materials

Coomassie Brilliant Blue G for Smart Colorimetric Determination of the Ionic Surfactants in Triton X-100 Solutions

The conditions for the smart colorimetric determination of cetylpyridinium chloride and sodium dodecyl sulfate by reaction with Coomassie brilliant blue G (CBBG) have been proposed. The nature of the absorption and fluorescence spectra of aqueous solutions of CBBG as a function of acidity has been investigated. A variety of reagent forms and associations with ionic surfactants have been demonstrated. The composition of the associates formed in the CBBG-cationic surfactant system has been established. The increase in the analytical signal of the cationic surfactant and the stabilization of the colloid-chemical state of the system during reactions in the organized medium of the nonionic surfactant Triton X-100 has been demonstrated. These effects are realized through association in premicellar solutions and as a result of the solubilization of components in Triton X-100 micellar solutions. The addition of long-chain cationic surfactants to the reagent occurs with the replacement of the heteroatom proton. The absorption of CBBG-cationic surfactant associates solutions increases with the length of the cationic surfactant hydrocarbon chain. Ethanol additives decrease the aggregation of CBBG. The technique of cationic surfactant determination has been tested in the analysis of the pharmaceutical. The results show that the simplicity of analytical signal registration with satisfactory correctness and acceptably high sensitivity of determination is an advantage of the developed technique.

Ant nest-like hierarchical porous imprinted resin-dispersive solid-phase extraction for selective extraction and determination of polychlorinated biphenyls in milk

Polychlorinated biphenyls (PCBs) are persistent toxic, organic chemicals that tend to accumulate in the food chain. This study reports the rapid and selective extraction and determination of PCBs (PCB81, 153, 105, 126, and 157) in milk samples by a dispersive solid-phase extraction (DSPE) coupled with gas chromatography-tandem mass spectrometry (GC-MS/MS). An ionic liquid-molecularly imprinted porous resin (IL-MIPPR) as a DSPE adsorbent was synthesized from m-aminophenol, formaldehyde, and 2,2'-benzidinedisulfonic acid as the monomer, crosslinker, and virtual template, respectively. The IL-MIPPR had a fast mass transfer (1.0 min) and good selectivity (imprinting factors of 1.8-3.0). The IL-MIPPR - DSPE - GC-MS/MS method exhibited good linearity (R² ≥ 0.9995), the limit of detections (LODs) < 0.6 pg/g, and the recoveries ranged from 82.8 % to 106 % with relative standard deviations ≤ 6.6 %. This method is thus better than previously reported methods in terms of the LOD, the adsorbent dosage, and the extraction time.

Method development using chemometric tools for determination of endocrine-disrupting chemicals in bottled mineral waters

A simple method was developed to determine 14 endocrine-disrupting chemicals (EDCs) in bottled waters, based on dispersive micro-solid phase extraction (d-µ-SPE) and liquid chromatography-mass spectrometry (LC-MS). Extraction was optimized using 2 ^k-1 factorial and Doehlert experimental designs. Optimized conditions were 80 mg C18, 25 min extraction at 1000 rpm, and 6 min desorption time. Repeatability was below 17 % for all EDCs. LOD and LOQ varied from 1.60 ng L^-1 (estradiol, E2) to 23.2 ng L^-1 (dimethylphthalate, DMP) and from 5.33 ng L^-1 (E2) to 77.3 ng L^-1 (DMP). We found DMP and bisphenol A (BPA) in samples after the heat treatment. DMP was up to 58.7 µg L^-1, while BPA was up to 1.34 µg L^-1. Tolerance of daily intake (TDI) for DMP were 2.50-2.94 µg kg^-1 day^-1 (children) and 1.43-1.68 µg kg^-1 day^-1 (adults). TDI for BPA were 0.03-0.07 µg kg^-1 day^-1 (children) and 0.01-0.04 µg kg^-1 day^-1 (adults).

Cationic Surfactant Modified 3D COF and Its Application in the Adsorption of UV Filters and Alkylphenols from Food Packaging Material Migrants

Hexadecyl trimethylammonium bromide (CTAB) micelles were applied in the synthesis of covalent organic frameworks (COFs) for the first time to achieve the synthesis of 3D COF from 2D materials. Benzidine, one raw material for COF, was enclosed in the CTAB micelles because of the hydrophobic effect, and thus the target COF, which can be formed immediately with the aid of p-toluenesulfonic acid, grew in a micelle guided 3D form. The synthesized 3D COF showed a flower-like structure, whereas the COF synthesized without CTAB showed a smooth structure. The diameter of the 3D COFs showed direct correlations with CTAB concentrations. Moreover, the CTAB modified COF also showed a dramatically improved fluorescence property in comparison with that of normal COFs. The synthesized 3D COF showed good adsorption performance for UV filters and alkylphenols with recoveries ranged from 90.2% to 99.8%, and it also showed good fluorescence response for Pb²⁺. The utility of CTAB modified COF was verified in the enrichment of UV filters and alkylphenols from food packaging material migrants.

Monodisperse cobalt(II) based metal-organic coordination polymer beads as a sorbent for solid-phase extraction of chlorophenoxy acid herbicides prior to their quantitation by HPLC

Metal-organic coordination polymer beads (MOCBs) are described for use as a sorbent for solid-phase extraction of chlorophenoxy herbides. By applying regulation of Co(II) ions, micro-sized monodisperse MOCBs were obtained through the microwave heating. The MOCBs-based method displays excellent extraction efficiency towards chlorophenoxy herbicides, specifically of 2-chlorophenoxyacetic acid, 4-chlorophenoxyacetic acid, 4-chloromethylphenoxyacetic acid, 2,4-dichlorophenoxyacetic acid, 2,4,5-trichlorophenoxyacetic acid and 2-(2,4-dichlorophenoxy)propionic acid. Following extraction, the herbicides were eluted with 8% formic acid in methanol and quantified by HPLC. The method, when applied to analyze spiked cereals, exhibits a wide linear range (from 0.6 to 1000 ng g^-1) and low limits of quantification (ranging from 0.10 to 0.25 ng g^-1). For a single column, the inter-day and intra-day precisions, expressed as the relative standard deviation are in the range of 2.5-6.8%. The batch-to-batch reproducibility (for n = 3) is <4.6%. For spiked cereal samples, relative recoveries are very good (90.3-102.3%, for n = 4). The extraction efficiency of MOCBs remains unchanged after reusing for 40 times. Graphical abstractSchematic presentation of Co(II)-doped metal-organic coordination polymer beads (Co(II)@MOCB) using for solid-phase extraction (SPE).

Poly (Octadecyl Methacrylate-Co-Trimethylolpropane Trimethacrylate) Monolithic Column for Hydrophobic in-Tube Solid-Phase Microextraction of Chlorophenoxy Acid Herbicides

Chlorophenoxy acid herbicides (CAHs), which are widely used on cereal crops, have become an important pollution source in grains. In this work, a highly hydrophobic poly (octadecyl methacrylate-co-trimethylolpropane trimethacrylate) [poly (OMA-co-TRIM)] monolithic column has been specially prepared for hydrophobic in-tube solid-phase microextraction (SPME) of CAHs in rice grains. Due to the hydrophobicity of CAHs in acid conditions, trace CAHs could be efficiently extracted by the prepared monolith with strong hydrophobic interaction. Several factors for online hydrophobic in-tube SPME, including the length of the monolithic column, ACN and trifluoroacetic acid percentage in the sampling solution, elution volume, and elution flow rate, were investigated with respect to the extraction efficiencies of CAHs. Under the optimized conditions, the limits of detection of the four CAHs fell in the range of 0.9–2.1 μg/kg. The calibration curves provided a wide linear range of 5–600 μg/kg and showed good linearity. The recoveries of this method ranged from 87.3% to 111.6%, with relative standard deviations less than 7.3%. Using this novel, highly hydrophobic poly (OMA-co-TRIM) monolith as sorbent, a simple and sensitive online in-tube SPME-HPLC method was proposed for analysis of CAHs residue in practical samples of rice grains.