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To achieve accurate and highly sensitive determination of advanced glycation end products (AGEs) in baked food, a magnetic solid phase extraction (MSPE) technique based on magnetic covalent organic frameworks (COFs) material was established to achieve the selective and efficient enrichment of two major AGEs (i. e. Nε-carboxymethyl)lysine (CML) and Nε-(carboxyethyl) lysine (CEL)) in baked foods. The quantitative analysis of CML and CEL was conducted with high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) method. Results showed that the synthesized magnetic COFs material showed big specific surface area and strong magnetism, which was suitable for MSPE. The optimum conditions of MSPE were as follows: the amount of adsorbent was 20 mg, the time of vortex extraction was 20 min, the elution solvent was 5% ammonia/methanol solution, the volume of elution solvent was 4 mL, the elution time was 15 min. The limits of detection of CML and CEL for the established method were 2.05 ng/mL and 2.31 ng/mL, respectively, while the limits of quantification were 6.83 ng/mL and 7.71 ng/mL, respectively. And intra-day and inter-day precisions were good (RSDintra-day ≤ 4.74%, RSDinter-day ≤ 5.38%). The recoveries of CML and CEL in typical food matrixes (i. e. biscuits and nuts) were in the range of 90.70% ~ 108.74% and 85.50% ~ 113.00%, respectively. Applying the analytical method established in this article to the determination of CML and CEL contents in 26 commercially available baked goods, it was found that the contents of CML and CEL in biscuits and pastries were in the range of (9.60 ± 0.16) ~ (78.10 ± 1.12) mg/kg, and (4.37 ± 0.23) ~ (26.70 ± 1.27) mg/kg, respectively; while the contents of CML and CEL in nuts were in the range of (6.49 ± 0.13) ~ (82.00 ± 0.98) mg/kg, and (6.65 ± 0.30) ~ (55.90 ± 0.67) mg/kg, respectively. The established method could effectively purify samples and significantly reduce matrix effect, and thus showed high accuracy for quantitative analysis. Furthermore, the synthesized magnetic COFs material could be recycled for 5 times, which was suitable for the determination of CML and CEL in baked food. [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]

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]

Through graded salting out with ammonium sulfate and dialysis, esterases were extracted and purified from goose liver, chicken liver and pig liver respectively, then their structures were characterized, and their inhibition responses to carbaryl as a pesticide model were further investigated. Results showed that the yield of goose liver esterase was the highest (14.58%), and that of chicken liver esterase was the lowest (8.82%) with the best thermal stability, while the protein mass concentration of pig liver esterase was the highest (12.47mg/mL); the protein molecular weights of all three kinds of animal liver esterases were 30 ~ 110 kDa with the leading one of 55 kDa, and that in chicken liver esterase was the highest (16.74%) while the lowest was in that of pig liver esterase (14.31%); these three kinds of animal liver esterases showed different sizes of protein particles with flake structures and smooth surfaces; in the carbaryl concentration range of 0.5~10.0 mg/L, the linear range (0.5~5.0 mg/L), the detection limit (0.29 mg/L) and IC50 (7.74 mg/L) of chicken liver esterase were the lowest, which could be used as a potential sensitive enzyme source for rapid detection of carbaryl. [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]