查看更多>>摘要：Spices had a worldwide market value greater than $20 billion in 2020. The price per kilogram or ton is high for many spices often due to intensive labor and handling requirements in their preparation, with black pepper as one example. Spices are produced in many countries, in plots ranging from fractions of a hectare to multihectare mechanized operations. From harvest through production and to final market package, spices pass through several steps in the supply chain that provide ample opportunity for fraud. Contamination with harmful plant materials, ingredient substitutions, and adulteration in spices are frequently encountered. In addition, spices in specific geographic regions can have distinctive characteristics from the localized growing conditions giving rise to changes in terpene profiles and other flavor components, creating variation in market price based on country of origin. The research reported here details a system for automated chemical analysis of 170 terpenes in spices and other botanicals by gas chromatography (GC), through enhancements to a proven bacterial identification system. The system integrates pattern recognition searches of custom spice databases to identify country of origin of most spices, aiding in the authentication of spices and detection of fraudulent ingredients. (c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )
查看更多>>摘要：In this study, a novel narrow capillary (i.e., 20 mu m i.d.) coating procedure was reported for the preparation and application of open-tubular (OT) column for the separation of casein (CN) protein variants in milk. Based on this approach, a new poly-L-lysine (PLL) grafted on graphene oxide stationary phase was developed for OT nano-liquid chromatography (OT-nano LC). In this preparation, methacryloyl graphene oxide nanoparticles (MGONPs) were synthesized and used as reactive monomer. Fused silica capillaries with 20 mu m i.d. were used for the preparation of OT column. After silanization of the capillary column, the stationary phase was prepared by MGONPs graft polymerization and PLL modification. It was shown that the use of MGONPs amount was important for the capillary coating. A column without PLL modification was also prepared for comparing the effect of PLL. SEM images of the column showed that MGONPs were bound to the surface of capillary in a dense monolayer. Alkylbenzenes (ABs) were used for the chromatographic characterization of the OT column. The results showed that the modification was successfully performed and allowed satisfactory separation of ABs. The developed OT column in the ProFlow nano-LC was applied to the separation of casein (CN) protein variants, including alpha(s1)-CN, alpha(s2)-CN, beta-CN and kappa-CN. Results indicated that the column provided a promising separation of casein protein variants due to both hydrophobic interactions and repulsive electrostatic interactions. Run-to-run and column-to-column reproducibilities were satisfactory (i.e., <= 3.12%). Real sample application of the OT column was demonstrated using a milk sample. Several isoforms of alpha(s1)-CN could be detected. All results demonstrated that the developed OT column with a novel coating procedure was promising for advanced nano-liquid chromatographic separations. (c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Phthalate esters (PAEs) are a typical group of endocrine-disrupting chemicals (EDCs) and widely found in the environment, which have attracted great concern due to the potential risks to environment and human health. It is urgent to develop a high-efficiency and high-sensitivity analytical approach for enrichment and determination of ultra-trace PAEs. Herein, magnetic covalent organic frameworks (Fe3O4@TAPB-DVA) were fabricated via a one-pot approach at room temperature and explored as a magnetic enrichment probe with high surface area (275.50 m(2)/g), good crystallinity, regular pore size distribution (3.1 nm) and outstanding saturation magnetization (26.5 emu/g). Accordingly, a simple and sensitive method based on magnetic solid-phase extraction (MSPE) combined with HPLC-MS/MS was established to detect ultra-trace PAEs from fine particulate matter (PM2.5) samples. The proposed method showed wide linear ranges (1-400 ng/L), good linearity (r > 0.9978) and high enrichment factors (EFs, 6.99-95.01 folds) with low detection limits (LODs) ranged from 0.01 to 0.5 ng/L (S/N >= 3). On this basis, the proposed method was substantially employed for sensitive detection of low-abundance PAEs from PM2.5 samples, suggesting the promising application of the Fe3O4@TAPB-DVA in sample enrichment. (C) 2022 Elsevier B.V. All rights reserved.
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