CHROMATOGRAPHIA
·
2022
·Vol. 85
·期 6
·507-517
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IF 2.213
Yang Jiawei,Zeng Tong,Xu Huimin,Ni Yonghao,Huang Liulian,Chen Lihui,Hu Hui-Chao
This paper aims to improve the signal response in headspace (HS) analysis over than the GC analysis with a classical splitless injection mode, and this was achieved by the development of high-pressure headspace (HP-HS) analysis method. Based on the theoretical analysis on the sampling principle of HS, the HP-HS concept was proposed in section one, indicative of possibility to achieve excellent signal response. In the proposed HP-HS technology, the complete transfer of gas sample from HS to GC column is achieved in a very short purge-off time in the splitless injection of GC using the high-pressure carrier gas. The sampling size was increased by adopting high-pressure auxiliary gas. The dilution effect of venting process on detected substance was greatly reduced by controlling the terminal pressure of venting process at a high level. With the HP-HS analysis technology, the optimal equilibration temperature and signal response for analytes with high or medium volatility in ten common solvents was determined, and the results showed that the HP-HS-GC method can achieve very high signal response and very low solvent effect on GC. For aqueous samples, the signal response of HP-HS-GC can be up to three times than that of the splitless GC analysis. The present technology has a great potential, in particular, in high sensitivity analysis of complicated samples with serious substrate effect.
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ANALYTICAL CHEMISTRY
·
2021
·
IF 6.986
Caiming Tang,Jianhua Tan,Caixing Tang,Deyun Liu,Peilin Zhang,Xianzhi Peng
Distributions of chlorine isotopologues are potentially a fingerprint feature of organochlorines. However, the exact distributions remain little known. This study measured compound-specific chlorine isotopologue distributions of six polychlorinated organic compounds (POCs) for source identification. Complete chlorine isotopologues of POCs were detected by gas chromatography coupled to high-resolution mass spectrometry. The measured relative abundances (Ameas), theoretical relative abundances (Atheo), and relative variations between Ameas and Atheo (ΔA) of chlorine isotopologues were determined. These ΔA values were applied to characterize differences in isotopologue distribution patterns, and the ΔA patterns directly illustrated the distribution characteristics. Perchloroethylene (PCE) and trichloroethylene (TCE) from two manufacturers were chosen as model analytes to develop and validate the analytical method, including precision, concentration dependency, and temporal drift. The ΔA values of isotopologues of the PCE and TCE chemicals were from −82.5 to 19.9‰ with standard deviations (SDs) of 0.3–16.9‰. In addition, the ΔA values of the first three isotopologues (with 0–2 37Cl atoms) were from −15.5 to 19.9‰ with SDs of 0.3–1.6‰, showing sufficient precisions. No concentration dependency and temporal drift of ΔA were observed. The method has been successfully applied to source identification for PCE and TCE in commercial chemicals and plastic materials, and four polychlorinated biphenyls in chemicals and sediments, demonstrating that the ΔA values and ΔA patterns were discernable for POCs from different sources. This study demonstrates that compound-specific chlorine isotopologue distributions of POCs are differentiable and measurable, proposing a novel approach to perform fingerprinting analysis for the distributions, which is anticipated to facilitate source identification for organochlorine pollutants.
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Egyptian Journal of Forensic Sciences
·
2019
·Vol. 9
·期 1
·1-13
·
IF 0
Middha Deepak,Negi Archna
Water-pipe tobacco smoking obsession has again spread worldwide. Especially, the younger generation is besotted with mu’assel (shisha) and avidly use these for smoking. Numbers of additives are being added in commercial brands of mu’assel (shisha) to impart diverse taste with amusing aroma. The name of only one of the masking flavours like strawberry, chocolate, vanilla etc. and not the chemical ingredients are printed on the packets of mu’assel. The manufactures remain silent about mentioning the chemical ingredients used for flavourings as they may not have scientific data about chemical compounds attributing to multiple flavours. There is also a shortfall in quality control owing to non-availability of technical procedure(s) to identify masking multiple flavouring additives. Many of these flavoured additives are either carcinogenic or potentially hazardous for human health. Ignoring health hazards, the avaricious manufacturers are intentionally adding multiple additives to make their products more addictive in order to increase their sales. The need of the hour is to unequivocally establish a technique for chemical profiling of the flavouring additives in mu’assel. In this paper, seven popular commercial brands of mu’assel were extracted, sonicated and analysed by GC-MS technique for detection of flavouring additives.Twenty-eight flavouring additives, i.e. camphor, linalool, benzyl ethanol, β-citronellol, menthol, vanillin, ethyl vanillin, eugenol, eucalptol, patchouli alcohol, nerol, rheosmin, musk ambrette, musk ketone, phenyl ethyl methyl ether, anethole, estragole, limonene, benzaldehyde, terpineol, phenyl ethyl butyrate, phenethyl isobutyrate, piperonal, methyl isobutyrate, methyl dihydro jasmonate, anisyl alcohol, trans-geraniol and sabinene along with nicotine were detected in varied proportions by GC-MS technique in seven seized popular commercial brands of mu’assel.A study on chemical profiling of flavouring additives in commercial mu’assel has yet not been reported. Henceforth, this forensic attempt was aimed to secure public health by chemically profiling the flavouring additives of mu’assel. Many of the detected additives may cause severe health problems. Moreover, the smoker may suffer from neuroticism and psychoticism that may lead to a number of cases pertaining to physical assaults and sexual harassment.
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SN Applied Sciences
·
2019
·Vol. 2
·期 1
·1-11
·
IF 0
Li Genrong,Yu Wenqin,Xiao Zhaojing,Long Mei,Tong Lanyan,Qiu Yue
A rapid, sensitive, and practical QuEChERS method coupled with gas chromatography–mass spectrometry was developed for the simultaneous determination of 16 chemical adjuvant residues in samples of fruits (apple, nectarine, grape) and vegetables (tomato, cucumber, spinach). All target compounds were separated in less than 16 min. Samples were extracted with acetonitrile, and the types of extraction salt and cleanup sorbent were optimized. The optimized method was validated by evaluating the linearity, accuracy, precision, and matrix effect. The recoveries of the 16 pesticides adjuvants ranged from 61.2 to 116.3% with relative standard deviations lower than 11.6%. Limits of detection ranged from 0.21 to 3.02 μg/kg, and limits of quantification ranged from 0.71 to 10.07 μg/kg. Finally, the developed method was successfully employed to identify and quantify pesticide adjuvant residues in the analysis of 30 real fruit and vegetable samples.
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HOLZFORSCHUNG
·
2018
·Vol. 72
·期 11
·973-978
·
IF 2.079
Hui-Chao Hu,Tong Zeng,Shaokai Zhang,Lihui Chen,Liulian Huang,Yonghao Ni
A solvent-assisted and pyrogallol (PG)-protected headspace gas chromatography (HS-GC) method was developed to determine the pinene (α- and β-pinene) content in the kraft pulping black liquor (BL). Ethanol (EtOH) addition eliminated pinene’s micelles in BL by complete dissolution in the EtOH/BL medium. PG was applied to protect pinene from oxidation during the sample storage and measurement. The results showed that, with a 25% (v/v) of EtOH content and a 0.1 g of PG in 5-ml of sample solution, a rapid and stable pinene HS extraction can be obtained in 20 min at 80°C. The method has high precision with relative standard deviations within 4.2%. The sensitivity [limits of quantification (LOQ) are ~140 μg l −1 ] was high, and a good accuracy (recovery=96.0–104%) was typical for the pinene detection. The presented method is simple, rapid, accurate and is suitable for pinene quantification in biorefinery related processes and it leads to the preparation of high-value chemicals.
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JOURNAL OF CHROMATOGRAPHY A
·
2024
·
IF 3.8
Wenhui Lu,Chunli Ding,Mingshuo Zhu
The process of globalization and industrialization has resulted in a rise in the theft of coal and other related products, thereby becoming a focal point for forensic science. This situation has engendered an escalated demand for effective detection and monitoring technologies. The precise identification of coal trace evidence presents a challenge with current methods, owing to its minute quantity, fine texture, and intricate composition. In this study, we integrated machine learning with the identification of volatiles to accurately differentiate coal geographical origins through the application of headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS). The topographic distribution of volatiles in coals was visually depicted to elucidate the subtle distinctions through spectra and fingerprint analysis. Additionally, four supervised machine learning algorithms were developed to quantitatively predict the geographical origins of natural coals utilizing the HS-GC-IMS dataset, and these were subsequently compared with unsupervised models. Remarkable volatile compounds were identified through the quantitative analysis and optimal Random Forest model, which offered a rapid readout and achieved an average accuracy of 100 % in coal identification. Our findings indicate that the integration of HS-GC-IMS and machine learning is anticipated to enhance the efficiency and accuracy of coal geographical traceability, thereby providing a foundation for litigation and trials.
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Foods
·
2024
·Vol. 13
·期 20
·3243
·
IF 4.7
Cun Ao,Xiaojun Niu,Daliang Shi,Xuxia Zheng,Jizhong Yu,Yingbin Zhang
Flat black tea (FBT) has been innovatively developed to alleviate homogenisation competition, but the dynamic changes in aroma components during the process remain unclear. This study employed HS-SPME-GC-MS to analyse the aroma components of tea samples from various processing stages of FBT, and to make a comparative assessment with conventional strip-like Congou black tea (SBT). Additionally, a proteomic analysis was conducted on fresh leaves, withered leaves, and frozen–thawed leaves. Significant changes were observed in the aroma components and proteins during the processing. The results of the multivariate and odour activity value analysis demonstrated that the principal aroma components present during the processing of FBT were linalool, (E)-2-hexen-1-al, methyl salicylate, geraniol, hexanal, benzeneacetaldehyde, (Z)-3-hexenyl butyrate, dimethyl sulphide, 2-methylbutanal, 2-ethylfuran, nonanal, nonanol, 3-methylbutanal, (Z)-3-hexen-1-ol, 2-pentylfuran, linalool oxide I, and β-myrcene. Freezing–thawing and final roasting are the key processing steps for forming the aroma quality of FBT. The final roasting yielded a considerable quantity of pyrazines and pyrroles, resulting in a high-fried aroma, but caused a significant reduction in linalool, geraniol, β-myrcene, and esters, which led to a loss of floral and fruity aromas. The freezing–thawing treatment resulted in an accelerated loss of aroma substances, accompanied by a decrease in the expression level of lipoxygenase and 2-C-methyl-D-erythritol 2,4-cyclodiphosphate synthase. The formation of aroma substances in the linoleic acid metabolic pathway and terpenoid metabolic process was hindered, which had a negative impact on tea aroma. This study elucidates the causes of unsatisfactory aroma quality in tea products made from frozen tea leaves, providing theoretical support for the utilisation of frostbitten tea leaves, and helps us to understand the mechanism of aroma formation in black tea.
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Food Chemistry-X
·
2024
·
IF 6.5
Shan Jiang,Pengfei Jiang,Dingding Feng,Meiran Jin,Hang Qi
The flavor of algae was one of the key factors for consumer acceptance. The objective of this study was to investigate the characteristic volatile compounds in cooking and seasoned cooking edible brown seaweeds ( Undaria pinnatifida and Laminaria japonica ). The gas chromatography-ion mobility spectrometry (GC-IMS) and electronic nose (E-nose) analysis showed that baking resulted in significant difference in flavor of brown seaweeds. However, the overall effect of cooking was not as significant as that of the seasoning solution treatment. Additionally, brown seaweeds treated with the seasoning solution were more acceptable. Undaria pinnatifida was found to contain 72 volatile flavor compounds, while Laminaria japonica had a total of 70. This study proved the applicability of GC-IMS combined with E-nose technology to detect the changes of volatile components of brown seaweeds after processing, providing beneficial knowledge and basic theory for the deep processing of brown seaweeds.
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FOOD RESEARCH INTERNATIONAL
·
2024
·
IF 7
Wenkui Guo,Meiru Cheng,Xuemei Dong,Chuan Liu,Yu Miao,Peng Du,Hong Chu,Chun Li,Libo Liu
This study employed a combination of principal component analysis (PCA) and gas chromatography-ion mobility spectrometry (GC-IMS) to examine the distinctive taste mixtures produced by Chinese spicy cabbage (CSC) fermented at varying temperatures. As the fermentation progressed, the pH gradually decreased and stabilized after the 11 days of fermentation, and the total content of organic acids and short-chain fatty acids increased. A total of 49 volatile mixtures were detected during CSC fermentation and storage for 21 days. These included 7 aldehydes, 6 alcohols, 7 esters, 6 ketones, 5 pyrazines, 4 sulfides, 4 phenols, 2 ethers, 2 olefins, and 1 acid. With time, the content of most volatile flavor substances decreased. PCA of the signal intensities of the volatile chemicals in the samples showed significant differences in the flavor of CSC fermented at different temperatures; consequently, the samples fermented at different temperatures were effectively separated in relatively independent regions of CSC. Therefore, low-temperature fermentation and storage at 4 °C were more suitable for CSC. Based on the identified volatile chemicals, HS-GC-IMS and PCA could effectively construct the flavour fingerprints of CSC samples. This study provided a theoretical basis for improving the fermentation quality of CSC.
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JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE
·
2017
·Vol. 98
·期 4
·1574-1583
·
IF 2.463
Shanshan Yu,Yufan Zhang,Yun Ran,Wenyi Lai,Zhaoshou Ran,Jilin Xu,Chengxu Zhou,Xiaojun Yan
BACKGROUND Steryl glycosides (SGs) are sterol conjugates found in various plants, especially in those making up human diets. It has been demonstrated that SGs have potential health benefits, and they could be used as food supplements in a variety of food matrixes. Marine microalgae are a potential resource for human food and ingredients. In this study, gas chromatography–triple quadrupole mass spectrometry (GC–QQQ-MS) was used to characterize unknown SGs in eight microalgae belonging to different classes ( Isochrysis galbana 3011, Pavlova viridis , Platymonas helgolandica , Conticribra weissflogii , Thalassiosira pseudonana , Nitzschia closterium , Gymnodinium sp., and Karlodinum veneficum ). RESULTS The SGs were first extracted from lyophilized algae with chloroform–methanol, purified by solid-phase extraction and analyzed as trimethylsilyl derivatives. Nine SGs have been identified. In particular, new SGs like occelasteryl glycoside and stellasteryl glycoside were found in Gymnodinium sp., 24-methylene cholesteryl glycoside was detected in P. helgolandica , and 4,24-dimethylcholestan-3-yl glycoside was identified as the main constituent of microalga K. veneficum . The results also showed that the compositions of SGs in different microalgae varied, with a range of 5.234 to 0.036 g kg −1 , and microalga P. viridis contained the most abundant SGs. CONCLUSION GC–QQQ-MS is a powerful tool to detect SGs with different structures from a variety of microalgae. The compositions of SGs in different microalgae varied greatly. Microalgae are a good source of highly valued SGs. © 2017 Society of Chemical Industry
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POLYMER
·
2024
·
IF 4.1
Sitong Liu,Jie Yi,Rui Dai,Meng Wai Woo,Zhulian He,Hui Chen
In this work, the migration of urea and/or formamide plasticizers in crosslinked starch/polyvinyl alcohol (PVA) films under UV irradiation has been accurately quantified by using a combination of GC-MS/MS and UV–Vis analysis. The crosslinked starch/PVA films, prepared with different amide plasticizers (urea, formamide, urea-formamide), were characterized via scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and X-ray photoelectron spectroscopy (XPS). After 7 days of UV irradiation, the starch/PVA film plasticized with urea-formamide (A 7 -SPF-UF) exhibited a flat surface morphology, high crystal stability, and highest thermal stability. The migration ratio of urea and formamide for A 7 -SPF-UF was also quantified to be 3.2 % and 4.5 %, respectively, using GC-MS/MS and UV–Vis analysis, indicating optimal migration resistance. The synergistic effect of urea and formamide as plasticizers built the dense network structure of A n -SPF-UF and improved the UV aging resistance, toughness and durability of the film. On one hand, this enhances the market competitiveness of the products; on the other hand, it promotes the development of environmentally friendly materials, aligning with sustainability requirements.
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EUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY
·
2019
·Vol. 121
·期 6
·1800521
·
IF 1.852
Honglei Mu,Haiyan Gao,Hangjun Chen,Xiangjun Fang,Yongjun Zhou,Weijie Wu,Qiang Han
Walnut ( Carya cathayensis Sarg.) oil contains over 85% unsaturated fatty acids, which are easily oxidized during storage. As a result, a large number of volatile oxidation compounds (VOCs) are formed during oxidation. The qualitative composition of VOCs in walnut oil and quantitative prediction of the oxidation parameters (peroxide value [POV], acid value [AV], and p -anisidine value [ p -AnV]) by VOCs are investigated through SPME/GC-MS combined with partial least-squares (PLS) regression analysis. Eighteen VOCs including aldehydes, alcohols, and acids are detected by SPME/GC-MS. According to the comprehensive scores of principal component analysis (PCA), 2-octenal, hexanal, 2-heptenal, 1-octen-3-ol, hexanoic acid, and nonanal are the main products formed during oxidation. Then PLS regression is applied to developing quantitative prediction models of oxidation parameters (POV, AV, and p -AnV) by VOCs. The PLS prediction models have a good performance, with determination coefficients (R 2 p ) of 0.993–0.997 for the prediction sets of the three oxidation parameters. Practical Applications : The quantitative relationship between VOCs and oxidation parameters is developed in this study, which provided a new method for monitoring the quality of walnut oil. The SPME/GC-MS combined with PLSR is a feasible and potential method for simultaneous qualitative and quantitative analysis of oxidation process. This method is proven to have a precise predictive ability and provided a potential application in the quality assessment of other nut products. Volatile oxidation compounds (VOCs) are detected by SPME/GC-MS in oxidized walnut ( Carya cathayensis Sarg.) oil. Following this determination, partial least-squares regression (PLSR) is applied to developing quantitative prediction models of oxidation parameters by VOCs.
研究领域:
食品科学
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分析化学
·
植物学
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危险品化学品经营许可证（带存储）