In order to accurately determine N-nitroso nornicotine(NNN) and its metabolites in rabbit blood,a high-performance liquid chromatography/tandem mass spectrometry method was established by optimizing chromatographic conditions and mass spectrometric conditions and using NNN-d4 as an internal standard.The samples were successively pretreated by protein precipitation,separated by a Waters-HILIC column,and analyzed by tandem mass detector under multi-reaction monitoring(MRM) mode.The results showed that the recoveries of NNN and its metabolites ranged from 80% to 111% with the relative standard deviations(RSDs) of 0.5% to 8.62% and the limits of detection of 0.039 to 0.217 ng/mL.This method is simple,sensitive,rapid,and suitable for the analysis of NNN and its metabolites in blood.
In this paper, we propose a new strategy for separation and determination of tobacco-specific N-nitrosamines (TSNAs), a group of strong carcinogens found only in tobacco products, by using CZE and CE-MS associated with SPE. Six TSNAs: N'-nitrosonornicotine, N'-nitrosoanatabine, N'-nitrosoanabasine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol, and 4-(methylnitrosamino)-4-(3-pyridyl)-1-butanol were simultaneously separated by either of two CZE methods, one of which worked with ammonium formate buffer (pH 2.5) and another with citrate buffer (pH 2.4), as well as a CE-MS method. The CZE conditions including pH and concentration of running buffer, capillary length, applied voltage, and capillary temperature were systematically optimized. For CE-MS method, an optimized sheath liquid consisted of methanol-water was used at a flow rate of 10 muL/min. With SPE procedure, our proposed CE-MS method was successfully applied to determine TSNAs after 15 min metabolism in rabbits. A comparison study between CZE and CE-MS methods for quantitative purposes was carried out, showing that both methods provided similar separation efficiency, selectivity, repeatability, linearity, and recovery. However, CE-MS method was better suited for the analysis of TSNAs in complicated biological samples for its sensitivity and extra information on molecular structure. Having good accordance with our previous work by using LC-MS, the new CE-MS method is expected to be an alternative to the LC-MS method and applied to study the metabolism of TSNAs.
To obtain insight into the key roasted sweet aroma compounds in mainstream cigarette smoke, 14 smoke components previously identified by application of sensory-directed analysis were simultaneously quantified by a gas chromatography-mass spectrometry (GC-MS) method. The targeted compounds were well separated in 22 minutes and showed good linear correlation (R2 more than 0.99) using the method. Mainstream smoke from 12 flue-cured and 3 blended cigarettes was analyzed with this method. 2-Hydroxy-3-methyl-2-cyclopenten-1-one showed the highest amount in all samples. The odor threshold in ethanol for each compound was determined and the odor activity value (OAV) was calculated as the ratio of its concentration in mainstream smoke to its odor threshold. This allowed an evaluation of the flavor compound's contribution to the smoke matrix. The result showed that, of the 14 compounds analysed, the contributions of 4-hydroxy-2, 5-dimethyl-3(2H)-furanone, 5-methylfurfural, and 3, 4-dimethyl-1, 2-cyclopentanedione to the roasted sweet aroma of mainstream smoke were the most significant according to OAV.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)