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According to the normal production conditions, 13 kinds of n-alkanes were added to the core material sheet production process to prepare heated tobacco products, and a GC-MS analysis method suitable for re-alkanes in the core material, filter and mainstream smoke particulate matter of heated tobacco products was established. The transfer behavior of re-alkanes in heated tobacco products was studied by measuring the content, release and mouth-to-mouth release of re-alkanes in heated tobacco products. The results showed that: 1) The particle phase transfer rates of 13 re-alkanes in mainstream smoke were 0~53. 5 %, the filter interception rate was 12. 6% ~ 50. 0%, the smoke support retention rate was 0. 2% ~ 35. 4%, the smoke core residue rate was 6. 4% ~ 29. 3%, and the loss rate was 0. 6% ~ 81. 5%; With the increase of relative molecular mass and boiling point, the transfer rate of particulate matter and the interception rate of filter in mainstream smoke of n-alkane compounds increased first and then decreased, the residual rate of cigarette core increased gradually, and the retention rate of cigarette support increased first and then stabilized. The smoke retention rate and filter rejection rate showed a good positive correlation with the boiling point of the compound within a certain range. 2) With the increase of the number of suction ports, the release amount of re-alkanes increased first and then decreased, but the order of the maximum release amount was inconsistent. The lower the boiling point of the compound, the earlier the order of the maximum release amount. 3) The coefficient of variation of the puff-by-puff release of re-alkanes ranged from 0. 28 to 0. 44. The coefficient of variation of the puff-by-puff release of tridecane ( boiling point 235°C) and tetradecane ( boiling point 254 °C) was small, and the puff-by-puff release stability was good. Based on the evaluation data of the retention rate of re-alkanes in heated tobacco products, the transfer rate of particulate matter in mainstream smoke, and the stability of puff-by-puff release, the boiling point range of additives suitable for heated tobacco products was proposed to be about 250 °C. [ABSTRACT FROM AUTHOR]

Introduction The comprehensive complication index (CCI) is a new index to comprehensively and systematically evaluate complication severity. The objective of this study was to evaluate the predictive ability of CCI on short—and long-term overall survival(OS) in patients with esophageal squamous cell carcinoma (ESCC) undergoing minimally invasive esophagectomy (MIE) based on a propensity Score Matching (PSM) analysis. Methods A total of 356 patients treated with radical MIE from 2013 to 2017 were included, and the primary outcome was OS, and the secondary outcomes were postoperative hospital stay and hospital costs. Firstly, the optimla cut-off value of CCI was determined by X-tile. PSM was used to balance the baseline characteristics. Second, we compared postoperative hospital stay and hospital costs between high- and low-CCI group. Third, the Kaplan–Meier survival curve was used to analyze survival difference. Fourth, univariate and multivariate Cox analysis was used to explore the independent risk factors of OS. Results The CCI > 24.2 was defined as high-CCI group and CCI≦24.2 was defined as low-CCI group. The high-CCI group had more hospital costs and longer hospital stay than the low-CCI group both before and after PSM (p < 0.001). The K-M analysis indicated that patients with high CCI had worse prognosis both before and after PSM (before matching: P < 0.001; after matching: P = 0.04). CCI was determined as independent prognostic factor both before and after PSM (before PSM, P = 0.002; after PSM, P = 0.025). Conclusion The CCI could quantify postoperative complications after esophagectomy. High CCI is associated with longer hospital stay and hospitalization costs, and is an independent risk factor for poor OS. [ABSTRACT FROM AUTHOR]

The CHIRALPAK-IC was used, and the mixed solution of V (re-hexane) : V (isopropanol) = 95 : 5 was used as the mobile phase, and diethylamine was used as the mobile phase additive. In normal phase chromatography mode, a chiral column-high performance liquid chromatography-diode array detector (HPLC-DAD ) method was developed for the separation and analysis of nicotine optical isomers in tobacco and tobacco products. The characterization and test results of this method indicated:) The linear relationship between S-( -)-nicotine and R-( +)-nicotine was in the range of 15 ~750 µg/mL and 0. 75 ~30. 00 µg/mL, respectively. The detection limit and limit of quantification were 0.2 mg/g and 0. 05 mg/g, respectively. 2) The precision of intra- and inter-day measurements of nicotine was less than 0. 85% and 4. 00%, respectively; the recovery rates of S-( - ) -nicotine and R-( + ) -nicotine were 94. 93% ~ 103. 70% and 92. 50% ~ 117. 50%, respectively. This indicated that the method had good precision and high recovery rate. Using this method to determine the nicotine optical isomers of 26 different types of tobacco and tobacco products, it was found that tobacco was mainly S-( - )-nicotine, only 6 samples were detected by R-( + )-nicotine. The proportion of nicotine quality was 0. 18% ~0.70% ; among the 10 finished cigarettes and their mainstream smoke, the proportion of R-( + )-nicotine in total cigarette smoke was higher than that of cigarette tobacco. [ABSTRACT FROM AUTHOR]

Normal and slim cigarettes with different filter ventilation and cigarette paper air permeability were rolled. The effects of filter ventilation, cigarette paper ventilation and ventilation distribution on nine phenolic aroma components release from mainstream cigarette smoke were investigated. The results showed the filter ventilation rate, paper ventilation rate negatively correlated to the releases of nine phenolic aroma components in cigarette smoke, and with the increase of ventilation rate, the decrease rate of maltol with caramel flavour and smaller molecular weight was higher, while the decrease rate of eugenol with smoky flavor and larger molecular weight was lower. No matter normal or small cigarettes, the paper and filter ventilation rate have different effects on the decrease of smoke composition, and the paper ventilation rate has greater influence than the filter ventilation rate. The effects of filter ventilation rate, paper ventilation rate and ventilation distribution on the release of nine phenolic aroma components in conventional cigarette smoke were greater than those in slim cigarette smoke. When the total ventilation rate was the same, the release of 9 phenolic aroma components in cigarette smoke with high filter ventilation rate and low paper ventilation rate was higher than that with low filter ventilation rate and high paper ventilation rate. [ABSTRACT FROM AUTHOR]

• The CCGlu-enhancing HS-SPME Arrow combined with GC-Orbitrap-MS was developed to determine 34 SACs in tobacco. • This method possessed satisfactory sensitivity with the LOQ values ranging from 0.07 to 5.97 ng/g and 11 analytes identified for the first time in this study. • PCA results of 45 practical samples showed SACs as potential indicators of three aroma types and geographical origins of Virginia tobacco in China. The identification and measurement of sulfur aroma compounds (SACs) to precisely describe tobacco quality and style have remained as significant topics in tobacco research for many years. However, the ultra-trace quantification of SACs in complex tobacco matrices poses a considerable challenge in analytical area. In this study, an accurate and sensitive analysis of SACs in tobacco through a natural deep eutectic solvent (NADES) enhancing headspace-solid-phase microextraction (HS-SPME) Arrow combined with GC-Orbitrap was developed. The NADES system composed of choline chloride and D-glucose (CCGlu) in the pretreatment possessed excellent enhancement of HS-SPME Arrow extraction efficiency for natural tobacco targets. To improve selectivity, GC-Orbitrap was applied that prominently reduced chemical interferences from the tobacco matrix, improving confidence in the determination and identification of SACs in tobacco. During method validation, the limit of quantification (LOQ) ranged from 0.07 to 5.97 ng/g, apparently lower than those reported previously. And acceptable accuracies were attained with relative recoveries ranging from 85.4 % to 111 %. Finally, the developed method was applied to 45 Virginia tobacco samples, and 23 SACs were identified, among which 11 analytes were detected for the first time in this study. The results were preliminarily analyzed using principal component analysis, demonstrating that SACs could be employed as useful variables to characterize the aroma types and geographical origins of tobacco in China, which might be suitable for monitoring tobacco quality. [ABSTRACT FROM AUTHOR]

In order to investigate the effect of different ventilation distribution on organic acid release from mainstream smoke of slim cigarette, the slim cigarette samples with different filter ventilation and cigarette paper air permeability were rolled, and the organic acid in mainstream smoke of samples were analyzed by GC-MS, the prediction models of organic acids release based on both filter and paper ventilation rate were established. The results were as follows: 26 kinds of organic acids were detected. With the increase of filter ventilation rate or paper ventilation rate, the decrease rate of organic acids with smaller molecular weight was higher, while that with larger molecular weight was smaller, and the effect of paper ventilation rate on the release of organic acids in cigarette smoke was greater than that of filter ventilation rate. When the total ventilation rate (V) was constant, the release of organic acids in cigarette smoke with high filter ventilation rate and low paper ventilation rate was higher than that with low filter ventilation rate and high paper ventilation rate. The prediction accuracy of the model of organic acid release was high, and the results further proved that the cigarette organic acid release was higher with the combination of high filter ventilation rate and low paper ventilation rate. [ABSTRACT FROM AUTHOR]

In order to investigate the puff-by-puff discipline of flavor components in the mainstream cigarette smoking, a 20-channel rotary disc smoker modified from a patent in laboratory was used to achieve the puff-by-puff smoking of cigarettes. A GC-MS quantitative analysis method for neutral and alkaline flavor components in single-mouthful particulate phase of mainstream cigarette smoke was established. By using the established analytical method, the puff-by-puff delivery discipline of flavor components and the effects of the permeability of cigarette paper and packaging paper were studied. The results showed that: 1) The established analytical method had a good precision and recovery and was suitable for the quantitative analysis of neutral and alkaline aroma substances in single-mouthful gaseous and granular phase of cigarette smoke. 2) The transport capacity of tar and nicotine in the mainstream cigarette smoke steadily increased with the increase in the number of suction mouths, and decreased with the increase in the permeability of cigarette paper and packaging paper. 3) The transmission of neutral and alkaline aroma components increased with the increase in the number of suction mouths, but the transmission of various flavor components was slightly different, and decreased with the increase of the permeability of cigarette paper and packaging paper. 4) The puff-by-puff contents of neutral and alkaline aroma components in gaseous and granular phase of the mainstream smoke per unit tar and nicotine were the lowest in the first puff, and then were in line with the number of suction puffs. [ABSTRACT FROM AUTHOR]

• An AP combination suitable for seven minor tobacco alkaloids analysis was first presented. • AP provides an overall improvement in ME correction for solvents and samples. • The quantitative results of samples are accurate in different experimental scenarios. • This method possessed good accuracy, precision, and long-term robustness. Tobacco alkaloids are important precursors of carcinogenic tobacco-specific nitrosamines. Therefore, accurate quantification of tobacco alkaloids is highly important. This study investigates the compensation effects of novel analyte protectants (APs) for matrix effects (MEs) to determine seven minor tobacco alkaloids (nornicotine, myosmine, anabasine, anatabine, nicotyrine, 2,3′-bipyridine, and cotinine) in mainstream cigarette smoke with high accuracy and robustness. By comparing the heights and shapes of the chromatographic peaks before and after the addition of APs to standard solutions prepared in dichloromethane and cigarette smoke solutions, the compensation effects of 12 APs and their combinations on the MEs of seven minor tobacco alkaloids were evaluated, and the best combination of 2-pyridylethylamine (2 mg/mL)+1,2-decanediol (1 mg/mL) was identified. This AP combination could effectively improve the shapes and increase the heights (by 7–371%) of chromatographic peaks for standard solutions prepared in dichloromethane and cigarette smoke solutions. Before the addition of this AP combination, the slope ratios of the calibration curves for two types of standard solutions of the seven target chemicals were 71.4–159.8%, while they were 87.4–105.6% after the addition, indicating that this AP combination reduced the matrix difference between pure solvent and cigarette smoke solution. After adding the AP combination, the standard curves of solutions prepared in dichloromethane showed good linearity (r 2 ≥ 0.999), the spiked recoveries were between 80.9% and 119.6%, and the inter- and intraday precisions were between 1.5–9.5% and 3.1–8.5%, respectively. Three commercial cigarette samples and one mixed standard solution were also tested under four different instrument working conditions to verify the long-term accuracy and ruggedness of the approach in routine real-world analysis of the method. The results showed that the RSD values were higher (3.5–25.4%) without the AP combination than that (<6.7%) with the AP combination. Because of its high accuracy, precision, and robustness, this method has good practical prospects. [ABSTRACT FROM AUTHOR]

[Display omitted] • Electromembrane extraction was first used to extract nicotine in inhaled aerosols. • Electromembrane extraction exhibited good selectivity and sample clean-up capability. • This method was used to analyze nicotine in aerosols from different tobacco products. • Wide linear correlation, good accuracy and low detection limit were confirmed. • Heated tobacco products, electronic cigarettes and tobacco cigarettes were compared. Heated tobacco products and electronic cigarettes are considered as alternatives to traditional tobacco cigarettes. However, it is crucial to monitor and compare the nicotine concentration in inhaled aerosols from these tobacco products, owing to the addictive nature and adverse effects of nicotine on human health. This study aimed to provide an electromembrane extraction (EME) combined liquid chromatography method to extract and determine nicotine in different inhaled aerosols. EME showed high extraction efficiency, selectivity, and sample clean-up capability. Under the optimal parameters, the linear range for nicotine was 0.1–200 mg L−1 (r2 > 0.9998), and the limit of detection was 0.02 mg L−1. Good precision was obtained with the intra- and inter-day relative standard deviations of 2.2 % and 2.8 %, respectively. Repeatability was satisfactory (<7.7 %), and recoveries ranged from 81.0 % to 112.8 %. Finally, this method has been successfully used for the determination and comparison of nicotine in aerosols from these three tobacco products. [ABSTRACT FROM AUTHOR]

• A GC-MS/MS combining with silylation method was developed to determine 171 hydroxyl flavour additives in cigarette smoke. • Silylation in combination with GC-MS/MS has advantages in terms of high selectivity and sensitivity. • The novel use of a fused silica splitter simplified installation of backflushing system and exhibited better performance. • This method possessed good accuracy, satisfactory sensitivity and long-term robustness. • The developed method was applied to 270 practical cigarette smoke samples and meaningful results of HFAs were obtained. Flavour additives with carboxyl and hydroxyl groups (FACHs), the key ingredients in characteristic flavours, are frequently detected in cigarette smoke. They are attracting increasing attention in regulating the flavour additives used in tobacco to curb youth tobacco use and prevent the use of additives that are harmful. In this study, a highly robust, sensitive, and precise method based on silylation and GC-MS/MS with an improved backflushing system was developed for the simultaneous analysis of 171 FACHs in cigarette smoke. Silylation has been shown to have advantages in terms of high selectivity and sensitivity to chemicals with carboxyl and hydroxyl groups, especially when combined with GC-MS/MS. The extraction and silylation conditions were optimised. Dichloromethane was used as the extraction agent. BSTFA in combination with 1% TMCS and 0.2% TMSI was selected as silylating agent for high silylation efficiency, particularly for hindered analytes. The method has been validated. The limit of detection (LOD) ranged from 0.6 to 332.3 ng/mL. 91.1% out of the analytes in QC samples had precisions lower than 10% during one month run. The improved backflushing system with a fused silica splitter was shown to be crucial in the excellent long-term robustness of the method. The developed method was used to determine flavour additives in 270 practical cigarette smoke samples with reliable results. A total of 154 FACHs were identified with wide-range levels among different cigarette brands. [ABSTRACT FROM AUTHOR]

[Display omitted] • A GC–MS/MS method was developed to determine 559 aroma compounds in cigarette smoke. • An analyte protectant mixture that suited wide polar range solvents was proposed. • The use of precolumn backflushing markedly improved the instrument robustness. • This method is fit-for-purpose in routine analysis of a large number of samples. Trace analysis of multi-targets in complex matrices such as cigarette smoke has always been a great challenge for analysts. In this paper, a high-throughput qualitative and quantitative method was developed and validated to determine 559 aroma compounds in mainstream smoke using gas chromatography-tandem mass spectrometry. Among four commonly used extraction solvents, dichloromethane showed obvious advantages in extracting the target aroma compounds with different polarity. An analyte protectant mixture consisting of 3-methoxy-1,2-propanediol, 1,2-octandiol, 1,2-nonanediol, and 1,2-tetradecanediol was first presented to compensate for the matrix effect, which was suitable for solvents of a wide polarity range such as hexane, dichloromethane, acetone, acetonitrile, and methanol. Moreover, the introduction of precolumn backflushing markedly improved the instrument robustness in analyzing complex cigarette smoke. The results showed that the system retained good stability after 30 days of injection. The proposed method performed well in terms of key validation parameters: accuracy (70.3–118.8% for 552 compounds), inter/intraday precision (0.1–10.7% and 0.2–18.2%), and sensitivity (limit of detection 0.12–102.54 ng/mL). Finally, this method was successfully applied to analyze 12 different commercial cigarette brands. The proposed method has good application prospects based on its robustness and may be used as a potential tool to transfer the cigarette design from an experience-dependent mode to a digital design mode. This method also shows potential in assaying aroma compounds in essentials, food or plant-based substrates. [ABSTRACT FROM AUTHOR]

• Exogenous dietary AGEs have been suggested to increase health risk. • Oral use tobacco products are used as substitute for cigarette smoking due to their "reduced risk" and no second-hand smoke. • Thus, oral use tobacco products may increase AGEs intake due to their oral form of use. • To the best of our knowledge, no survey of CML and CEL levels in oral use tobacco products has been reported. • The free and total CML and CEL in different oral use tobacco products was determined in this work for the first time. • What's more, the relationship of CML (or CEL) and lysine, total amino acid, reducing carbohydrates was studied also. Exogenous dietary advanced glycation endproducts (AGEs) have been suggested to increase health risk. Oral use tobacco products are used as substitute for cigarette smoking due to their "reduced risk" and no second-hand smoke. They may increase AGEs intake due to their oral form of use. However, research on AGEs in oral use tobacco products is limited. A HPLC-MS/MS method was developed to survey free and total Nε-Carboxymethyllysine (CML) and Nε-Carboxyethyllysine (CEL) levels in different oral use tobacco products in this work. HPLC conditions, such as HPLC column and mobile phase additive were optimized. With the optimized conditions, analytical method performance for three types of oral use tobacco matrix (i.e. CRP2, gum and dissolvable tobacco product) was characterized. CML and CEL showed higher recovery in all three sample matrix, and the recovery of CML and CEL was in the range of 88.7%-120%, 90.0%-110%, respectively. The developed method showed good intra-day and inter-day precision with RSDs for both free and total CML (or CEL) of less than 9.7%. Limit of detections (LODs) of CML and CEL were 0.36 and 0.25 ng/mL, respectively. Sample analysis for 21 oral use tobacco products was conducted with the developed method. As for oral use tobacco products, total CML and CEL was much more than those of their free state, indicating that CML and CEL exist mainly protein adducts. In addition, the content of CML was higher than that of CEL for both free and total state. Oral use tobacco products I (i.e. dry snuff, moist snuff, suns and chew) had the highest CML (i.e. 44.89–608.69 µg/g) and CEL (i.e. 15.98–77.70 µg/g) levels, compared with oral use tobacco products II (i.e. gum) with the least CML (i.e. 0.7–0.8 µg/g) and CEL (i.e. 0.14–0.18 µg/g) levels. It mainly depended on the composition and processing technology of oral use tobacco products. Both total CML and CEL showed linear relationship with lysine and total amino acid (i.e. R > 0.77). However, there was no linear relationship between total CML (or CEL) and total reducing carbohydrates (i.e. R < 0.5). [ABSTRACT FROM AUTHOR]

Gas chromatography–mass spectrometry with electron ionization and positive-ion chemical ionization and comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry (GC × GC–TOF-MS) were applied for the characterization of the chemical composition of complex hydrocarbons in the non-polar neutral fraction of cigarette smoke condensates. Automated data processing by TOF-MS software combined with structured chromatograms and manual review of library hits were used to assign the components from GC × GC–TOF-MS analysis. The distributions of aliphatic hydrocarbons and aromatics were also investigated. Over 100 isoprenoid hydrocarbons were detected, including carotene degradation products, phytadiene isomers and carbocyclic diterpenoids. A total of 1800 hydrocarbons were tentatively identified, including aliphatic hydrocarbons, aromatics, and isoprenoid hydrocarbons. The identified hydrocarbons by GC × GC–TOF-MS were far more than those by GC–MS. [Copyright &y& Elsevier]

• Sulfonated functionalized magnetic COFs were prepared through a facile strategy. • The resultant composite featured mixed-mode and multiple interactions. • It exhibited excellent capture ability for β-agonists and fluoroquinolones. • Validated MSPE–LC–MS/MS method quantified β-agonists and fluoroquinolones in real samples. In this work, an efficient method for the determination of β-agonists and fluoroquinolones was established, based on a mixed-mode sorbent of magnetic sulfonated covalent organic framework composites. By coupling with HPLC–MS/MS, the main factors that affect the extraction procedure were optimized. Under the optimal conditions, the proposed HPLC–MS/MS method was successfully utilized for the extraction of β-agonists and fluoroquinolones in milk and pork meat samples. The method showed good linearities (R 2 ≥ 0.9916), and low LOQs of 0.1–0.2 ng g−1 for β-agonists and fluoroquinolones. The adsorption mechanism was investigated with the assistance of quantum chemistry calculation method, and it is worth noting that the sorbent relied mainly on the multiple adsorption mechanisms, including π–π stacking, hydrophobic, electrostatic attraction and hydrogen-bonding interactions. This work not only provides a simple method for the preparation of a mixed-mode sorbent, but also a routine analysis strategy for monitoring the illegal use of β-agonists and fluoroquinolones. [ABSTRACT FROM AUTHOR]