Abstract
The large-scale simultaneous extraction and concentration of aqueous solutions of triazine analogs, and aflatoxins, through a hydrocarbon-based membrane (e.g., polyethylene, polyethylene/polypropylene copolymer) under ambient temperature and atmospheric pressure is reported. The subsequent adsorption of analyte in the extraction chamber over the lignin-modified silica gel facilitates the process by reducing the operating time. The maximum adsorption capacity values for triazine analogs and aflatoxins are mainly adsorption mechanism-dependent and were calculated to be 0.432 and 0.297 mg/10 mg, respectively. The permeation, and therefore the percentage of analyte extracted, ranges from 1% to almost 100%, and varies among the solvents examined. It is considered to be vapor pressure- and chemical polarity-dependent, and is thus highly affected by the nature and thickness of the membrane, the discrepancy in the solubility values of the analyte between the two liquid phases, and the amount of adsorbent used in the process. A dependence on the size of the analyte was observed in the adsorption capacity measurement, but not in the extraction process. The theoretical interaction simulation and FTIR data show that the planar aflatoxin molecule releases much more energy when facing toward the membrane molecule when approaching it, and the mechanism leading to the adsorption.
Highlights
IntroductionChlorine-containing atrazine, propazine, and trietazine are, for the first time, being used on a large scale as derivatizing reagents in acetonitrile for enriching the purity of sulfur-containing acids under alkaline conditions [4]
Heterocyclic triazine analogs are a crucial precursor for various herbicides [1–3]
Microscale membrane extraction has recently become the preferred option for sample preparation in numerous cases because of its simplicity, low operational costs, and high enrichment factors
Summary
Chlorine-containing atrazine, propazine, and trietazine are, for the first time, being used on a large scale as derivatizing reagents in acetonitrile for enriching the purity of sulfur-containing acids under alkaline conditions [4] Melamine is another example of a chemically similar symmetric triazine with numerous common nonherbicide applications [5–11]. Many HPLC-oriented methods have been developed for monitoring the food chain for aflatoxin contamination These methods are usually combined with an extraction process to enrich or recover the analyte before analysis [32–36]. Silica gel modified with a native lignin molecule was used as an adsorbent for facilitating the subsequent process of concentrating an aqueous solution of various triazine analogs and aflatoxins on a large scale, after hydrocarbon-based membrane extraction under ambient temperature and atmospheric pressure. The adsorption capacity is measured for several selected analytes, and its dependence on the adsorption mechanism or on the steric hindrance of the analyte is explored through the FTIR approach
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