Rapid and sensitive determination of low concentrations of nicotine in plasma by gas chromatography with nitrogen-specific detection

Effects of chronic inhalation of electronic cigarettes containing nicotine on glial glutamate transporters and α-7 nicotinic acetylcholine receptor in female CD-1 mice

Alteration in glutamate neurotransmission has been found to mediate the development of drug dependence, including nicotine. We and others, through using western blotting, have reported that exposure to drugs of abuse reduced the expression of glutamate transporter-1 (GLT-1) as well as cystine/glutamate antiporter (xCT), which consequently increased extracellular glutamate concentrations in the mesocorticolimbic area. However, our previous studies did not reveal any changes in glutamate/aspartate transporter (GLAST) following exposure to drugs of abuse. In the present study, for the first time, we investigated the effect of chronic exposure to electronic (e)-cigarette vapor containing nicotine, for one hour daily for six months, on GLT-1, xCT, and GLAST expression in frontal cortex (FC), striatum (STR), and hippocampus (HIP) in outbred female CD1 mice. In this study, we also investigated the expression of alpha-7 nicotinic acetylcholine receptor (α-7 nAChR), a major pre-synaptic nicotinic receptor in the glutamatergic neurons, which regulates glutamate release. We found that inhalation of e-cigarette vapor for six months increased α-7 nAChR expression in both FC and STR, but not in the HIP. In addition, chronic e-cigarette exposure reduced GLT-1 expression only in STR. Moreover, e-cigarette vapor inhalation induced downregulation of xCT in both the STR and HIP. We did not find any significant changes in GLAST expression in any brain region. Finally, using liquid chromatography-tandem mass spectrometry (LC-MS/MS) techniques, we detected high concentrations of nicotine and cotinine, a major metabolite of nicotine, in the FC tissues of e-cigarette exposed mice. These data provide novel evidence about the effects of chronic nicotine inhalation on the expression of key glial glutamate transporters as well as α-7 nAChR. Our work may suggest that nicotine exposure via chronic inhalation of e-cigarette vapor may be mediated in part by alterations in the glutamatergic system.

Development of a simple sample preparation technique for gas chromatographic-mass spectrometric determination of nicotine in edible nightshades (Solanaceae)

The purpose of this study was to develop a rapid analytical method for the reliable determination of low concentrations of nicotine in foods for large numbers of samples. Food material was extracted using a simple liquid-liquid extraction method. For processed foods, further clean-up steps had to be employed to eliminate interfering compounds. The determination of nicotine was performed by gas chromatography-mass spectrometry. Quantitative analysis was accomplished using deuterium labeled nicotine as an internal standard. Recoveries of over 95% were obtained for a single step extraction, as well as for a multiple-stage extraction procedure, respectively. The method has been applied to the determination of nicotine in edible nightshades (i.e. tomatoes, potatoes and aubergines) and their processed products.

Simple and sensitive method for determination of nicotine in plasma by gas chromatography

Smoking and other forms of nicotine consumption are among the most important risk factors for cardiovascular disease and cancer. Many of the cessation therapies require administration of nicotine. Accordingly, precision analysis for nicotine in plasma has become increasingly important. Several of the recently published methods require elaborate sample handling and/or processing. We report a simple, rapid and reliable gas chromatography method with a high sensitivity for determination of unchanged nicotine in plasma, which can be used in the processing and quantification of large series of nicotine samples, e.g., in clinical trials of nicotine-based smoking or tobacco cessation drug delivery systems.

Determination of nicotine and cotinine in human plasma by liquid chromatography-tandem mass spectrometry with atmospheric-pressure chemical ionization interface

Here we report a sensitive liquid chromatographic-tandem mass spectrometric (LC-MS-MS) method capable of quantifying nicotine down to 1 ng/ml and cotinine to 10 ng/ml from 1.0 ml of human plasma. The method was validated over linear ranges of 1.0-50.0 ng/ml for nicotine and 10.0-500.0 ng/ml for cotinine, using deuterated internal standards. Compounds were simply extracted from alkalinized human heparinized plasma with methylene chloride, reconstituted into a solution of acetonitrile, methanol and 10 mM ammonium acetate (53:32:15, v/v) after the organic phase was dried down, and analyzed on the LC-MS-MS, which is a PE Sciex API III system equipped with a Keystone BDS Hypersil CI8 column and atmospheric pressure chemical ionization (APCI) interface. The between-run precision and accuracy of the calibration standards were < or = 6.42% relative standard deviation (R.S.D.) and < or = 11.8% relative error (R.E.) for both nicotine and cotinine. The between-run and within-run precision and accuracy of quality controls, (2.5, 15.0, 37.5 ng/ml for nicotine and 25.0, 150.0, 375.0 ng/ml for cotinine), were < or = 6.34% R.S.D. and < or = 7.62% R.E. for both analytes. Sample stabilities in chromatography, in processing and in biological matrix were also investigated. This method has been applied to pharmacokinetic analysis of nicotine and cotinine in human plasma.

Simultaneous determination of nicotine and cotinine in various human tissues using capillary gas chromatography/mass spectrometry

A reliable and sensitive method for the simultaneous determination of nicotine and cotinine concentrations in various human tissues was developed using capillary gas chromatography/mass spectrometry. Nicotine and cotinine were extracted using a 3-step solvent extraction procedure and quinoline as an internal standard. Quantification was carried out by single ion monitoring using ions of m/z 133 for nicotine, m/z 176 for cotinine and m/z 129 for quinoline. The lower limit of detection was 5 ng/g for nicotine and 10 ng/g for cotinine, in each tissue sample. The calibration curves of various tissues were linear in the concentration range from 5-1,200 ng/g for nicotine and 10-1,500 ng/g for cotinine. The accuracy and precision of this method were examined using human tissues and the results were satisfactory. The distribution of nicotine and cotinine was measured in tissues from 10 human autopsies. Nicotine was detected in every tissue examined at a level seen in habitual smokers. The nicotine concentration was high in the liver, kidney, spleen and lung, and low in adipose tissue. The cotinine level was highest in the liver. The tissue/blood concentration ratios of nicotine and cotinine were most stable in skeletal muscle, where the level of these drugs was close to that in whole blood. Skeletal muscle is, therefore, considered to be the most suitable tissue sample for toxicological examination, when acquisition of blood samples is not feasible.

Determination of nicotine and its main metabolites in urine by high-performance liquid chromatography

Nicotine and its main metabolites (cotinine, trans-3'-hydroxycotinine, trans-3'-hydroxycotinine glucuronide, nicotine-1'-N-oxide and 3-pyridylcarbinol) were analysed in urine after liquid-liquid extraction by high-performance liquid chromatography using norephedrine as internal standard, ultraviolet detection at 260 nm and scanning ultraviolet spectra with a photodiode-array detector. The conjugated trans-3'-hydroxycotinine was determined after enzymatic hydrolysis. Specific determination of 3-pyridylcarbinol was also carried out. Owing to its good selectivity, sensitivity and reproducibility, the method was applied to the analysis of urine samples from smokers and non-smokers. The results obtained suggest that the urinary markers used to assess active smoking or exposure to environmental tobacco smoke must be not only nicotine and cotinine, but also their main free and conjugated metabolites.

Gas chromatographic analysis of nicotine and cotinine in hair

Non-invasive validation of cigarette- or cigar-smoking behaviour is necessary for large population studies. Urine or saliva samples can be used for confirmation of recent nicotine intake by analysis of cotinine, the major metabolite of nicotine. However, this test is not suitable for validation of survey data, since the quantification of cotinine in saliva only reflects nicotine exposure during the preceding week. To validate information on tobacco use, we investigated hair samples for quantifying nicotine and cotinine by gas chromatography-mass spectrometry. Hair (about 50-100 mg) was incubated in 1 M sodium hydroxide at 100 degrees C for 10 min. After cooling, samples were extracted by diethyl ether, using ketamine as an internal standard. Drugs were separated on a 12-m BP-5 capillary column, and detected using selected-ion monitoring (m/z 84, 98 and 180 for nicotine, cotinine and ketamine, respectively). Hair from non-smokers and smokers contained nicotine and cotinine. Although it is difficult to determine an absolute cut-off concentration, more than 2 ng of nicotine per milligram of hair can be used to differentiate smokers from non-smokers. Some applications of this technique are developed to determine the status of passive smokers, the gestational exposure in babies and the pattern of an individual's nicotine use by cutting strands of hair into sections of one-month intervals.