Simultaneous determination of NNK and its metabolites in mouse tissue for evaluating the effects of chronic alcohol consumption on the metabolism of NNK in mouse liver and lung.

A hydrophilic-interaction liquid chromatography-tandem mass spectrometry (HILIC-MS-MS) method was developed for the determination of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and its metabolites in mouse liver and lung. The limits of detection of all analytes were in the range 0.017-0.057 ng mL(-1), and recovery ranged from 88.4-119.8 % with intra and inter-day precision in the range 0.89-6.03 % and 1.01-6.97 %, respectively. This simple and accurate method was used to evaluate the effect of chronic alcohol consumption on NNK bioactivation in mouse tissue. Time-course curves for NNK and its metabolites were generated, and the areas under the curves (AUCs) were compared. It was found that target tissues of NNK carcinogenesis in C57BL/6 mice contained high levels of α-hydroxylation metabolites of NNK and its carbonyl reduction metabolite, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL). The most pronounced effect of alcohol was to enhance α-hydroxylation of NNK in mouse lung and liver, which suggests that chronic alcohol consumption may increase the risk of carcinogenicity associated with NNK in mice.

SPE-HPLC-MS/MS method for the trace analysis of tobacco-specific N-nitrosamines and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol in rabbit plasma using tetraazacalix[2]arene[2]triazine-modified silica as a sorbent.

Tobacco-specific N-nitrosamines (TSNAs), including N'-nitrosonornicotine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, N'-nitrosoanatabine, and N'-nitrosoanabasine, have been implicated as a source of carcinogenicity in tobacco and cigarette smoke. We present a rapid and effective method comprising SPE based on tetraazacalix[2]arene[2]triazine-modified silica as sorbent and analysis with HPLC-MS/MS for the determination of TSNAs and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), a metabolite of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, in rabbit plasma. The linear dynamic ranges were 10-2000 pg/mL for NNAL and 4-2000 pg/mL for the four TSNAs with good correlation coefficients (>0.9965). The LODs were in the range of 0.9-3.7 pg/mL, and the LOQs were between 2.9 and 12.3 pg/mL. The accuracies of the method were also evaluated and found to be in the range of 90.1-113.3%. This method is promising to be applied to the preconcentration and determination of TSNAs and NNAL in smoke and human body fluids.

Simultaneous determination of NNK and its seven metabolites in rabbit blood by hydrophilic interaction liquid chromatography-tandem mass spectrometry.

A hydrophilic interaction liquid chromatographic-tandem mass spectrometric (HILIC-MS-MS) method for investigation of the in vivo metabolism of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), a potent carcinogen, in rabbit blood has been developed and validated. This method achieved excellent repeatability and accuracy. Recovery ranged from 76.9 to 116.3 % and precision (as RSD) between 0.53 and 6.52 %. Linearity was good for all compounds (R(2)>0.9990) and the limit of detection (LOD) ranged from 0.016 to 0.082 ng mL(-1). Pharmacokinetic analysis indicated that NNK was rapidly eliminated in vivo in rabbit blood and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) was the major metabolite. The hydroxy acid, keto acid, and NNAL-N-oxide were also important metabolites in rabbit blood. It is probable that α-methylene hydroxylation was the major pathway of α-hydroxylation of NNK and NNAL in the rabbit.

Analysis of N'-nitrosonornicotine and its metabolites in rabbit blood with liquid chromatography/tandem mass spectrometric method.

N'-nitrosonornicotine (NNN) is a strong carcinogen. The metabolic study of NNN in vivo will help us to further understand it, however, trace detection in complex matrices requires highly sensitive detection methods. After the chromatographic conditions and mass spectrometric conditions had been optimized and confirmed, a method for determining NNN and its metabolites in rabbit blood by high-performance liquid chromatography/tandem mass spectrometry (HPLC-MS/MS) was established. The results showed that precisions (R.S.Ds) were between 0.5% and 8.62%, the recoveries ranged from 80% to 111%. Linearity was observed for all compounds with detection limits ranging from 0.039 ng mL⁻¹ to 0.217 ng mL⁻¹. Metabolic curves and pharmacokinetic parameters were obtained for NNN and its metabolites. The elimination half-life of NNN was 30 min and the main metabolite of NNN was 4-hydroxy-4-(3-pyridyl)-butyric acid (hydroxy acid) and the major metabolic pathway was 5'-hydroxylation and subsequent secondary metabolite formation.