A liquid chromatography-mass spectrometry method for nicotine and cotinine; utility in screening tobacco exposure in patients taking amiodarone

Review of HPLC-MS methods for the analysis of nicotine and its active metabolite cotinine in various biological matrices

In recent years, tobacco smoking is a risk factor for a series of diseases including cardiovascular diseases, cerebrovascular diseases, and cancers. Nicotine, the primary component of tobacco smoke, is mainly transformed to its active metabolite cotinine, which is often used as biomarker for tobacco exposure for its higher blood concentration and longer residence time than nicotine. Various analytical methods have been developed for the determination of nicotine and cotinine in biological matrices. This article reviewed the HPLC-MS based methods for nicotine and/or cotinine analysis in various biological matrices. The sample preparation, mass and chromatographic conditions and method validation results of these methods have been summarized and analyzed. Sample was mainly pretreated by protein precipitation and/or extraction. Separation was achieved using methanol and/or acetonitrile:water (with or without ammonium acetate) on C18 columns, and acetonitrile:water (with formic acid, ammonium acetate/formate) on HILIC columns. Nicotine-d3, nicotine-d4 and cotinine-d3 were commonly used internal standards. Other non-deuterated IS were also used such as ritonavir, N-ethylnorcotinine, and milrinone. For both nicotine and cotinine, the calibration range was 0.005-35000 ng/mL, the matrix effect was 75.96% - 126.8% and the recovery was 53% - 124.5%. The two analytes were stable at room temperature for 1-10 days, at -80 °C for up to 6 months, and after 3-6 freeze-thaw cycles. Comedications did not affect nicotine and cotinine analysis.

Application of HPLC-QQQ-MS/MS and New RP-HPLC-DAD System Utilizing the Chaotropic Effect for Determination of Nicotine and Its Major Metabolites Cotinine, and trans-3'-Hydroxycotinine in Human Plasma Samples

The routine techniques currently applied for the determination of nicotine and its major metabolites, cotinine, and trans-3′-hydroxycotinine, in biological fluids, include spectrophotometric, immunoassays, and chromatographic techniques. The aim of this study was to develop, and compare two new chromatographic methods high-performance liquid chromatography coupled to triple quadrupole mass spectrometry (HPLC-QQQ-MS/MS), and RP-HPLC enriched with chaotropic additives, which would allow reliable confirmation of tobacco smoke exposure in toxicological and epidemiological studies. The concentrations of analytes were determined in human plasma as the sample matrix. The methods were compared in terms of the linearity, accuracy, repeatability, detection and quantification limits (LOD and LOQ), and recovery. The obtained validation parameters met the ICH requirements for both proposed procedures. However, the limits of detection (LOD) were much better for HPLC-QQQ-MS/MS (0.07 ng mL⁻¹ for trans-3′-hydroxcotinine; 0.02 ng mL⁻¹ for cotinine; 0.04 ng mL⁻¹ for nicotine) in comparison to the RP-HPLC-DAD enriched with chaotropic additives (1.47 ng mL⁻¹ for trans-3′-hydroxcotinine; 1.59 ng mL⁻¹ for cotinine; 1.50 ng mL⁻¹ for nicotine). The extraction efficiency (%) was concentration-dependent and ranged between 96.66% and 99.39% for RP-HPLC-DAD and 76.8% to 96.4% for HPLC-QQQ-MS/MS. The usefulness of the elaborated analytical methods was checked on the example of the analysis of a blood sample taken from a tobacco smoker. The nicotine, cotinine, and trans-3′-hydroxycotinine contents in the smoker’s plasma quantified by the RP-HPLC-DAD method differed from the values measured by the HPLC-QQQ-MS/MS. However, the relative errors of measurements were smaller than 10% (6.80%, 6.72%, 2.04% respectively).

Role of Environmental Factors in the Development of Pediatric Eosinophilic Esophagitis

BACKGROUND

Despite accumulating data on the pathogenesis of eosinophilic esophagitis, not much is known about risk factors for the development of the disease. The role of factors such as smoking, breastfeeding, early antibiotic exposure and other factors that have been associated with other allergic diseases has not been well studied in children with eosinophilic esophagitis.

AIM

To explore the role of environmental and medication exposures in the development of pediatric eosinophilic esophagitis.

METHODS

We conducted a cross-sectional case-control study, utilizing a parent and child questionnaire and medical chart review. Urine cotinine levels, measured by high-performance liquid chromatography, were obtained as objective evidence for smoking exposure.

RESULTS

One hundred and two children with eosinophilic esophagitis and 167 controls were recruited. The controls were mainly diagnosed with functional gastrointestinal disorders (33%) and gastroesophageal reflux disease (29%). Food allergy, specifically for peanuts and tree nuts, and allergy to pollen, tree, and grass were significantly higher among eosinophilic esophagitis children. Smoking exposure, both primary and secondary, was not associated with pediatric eosinophilic esophagitis when compared to controls (odds ratio 0.96, 95% confidence interval 0.58-1.59). Furthermore, early smoking exposure in the first year of life was higher among controls. Common accepted risk factors for allergy and atopy, such as breastfeeding practices, antibiotics exposure, animals' exposure, and others, were not found to be associated with eosinophilic esophagitis in our study.

CONCLUSION

Common risk factors in other allergic and atopic conditions were not found to be associated with eosinophilic esophagitis.

Recent advances in MS methods for nicotine and metabolite analysis in human matrices: clinical perspectives

Tobacco smoking is a major global health issue and represents the leading cause of preventable death in the developed countries. Nicotine is a major alkaloid found in tobacco products and its detection with its metabolites in human matrices is generally used for assessing tobacco consumption and second hand exposure. Several analytical techniques have been developed for the detection of nicotine and its metabolites, and MS coupled with chromatography is considered the standard reference method because of its superior sensitivity and specificity. In this work, we reviewed nicotine metabolism, clinical MS and the latest (2009-2014) development of MS-based techniques for measurement of nicotine and metabolites in human matrices. Appropriate biomarker and matrix selection are also critically discussed.

Estimation of cutoff values of cotinine in urine and saliva for pregnant women in Poland

Setting appropriate cutoff values and the use of a highly sensitive analytical method allow for correct classification of the smoking status. Urine-saliva pairs samples of pregnant women in the second and third trimester, and saliva only in the first trimester were collected. Offline SPE and LC-ESI-MS/MS method was developed in the broad concentration range (saliva 0.4-1000 ng/mL, urine 0.8-4000 ng/mL). The mean recoveries were 3.7 ± 7.6% for urine and 99.1 ± 2.6% for saliva. LOD for saliva was 0.12 ng/mL and for urine 0.05 ng/mL; LOQ was 0.4 ng/mL and 0.8 ng/mL, respectively. Intraday and interday precision equaled, respectively, 1.2% and 3.4% for urine, and 2.3% and 6.4% for saliva. There was a strong correlation between salivary cotinine and the uncorrected cotinine concentration in urine in the second and third trimesters of pregnancy. The cutoff values were established for saliva 12.9 ng/mL and urine 42.3 ng/mL or 53.1 μg/g creatinine with the ROC curve analysis. The developed analytical method was successfully applied to quantify cotinine, and a significant correlation between the urinary and salivary cotinine levels was found. The presented cut-off values for salivary and urinary cotinine ensure a categorization of the smoking status among pregnant women that is more accurate than self-reporting.

The effect of nicotine on sensorimotor gating is modulated by a CHRNA3 polymorphism

RATIONALE

Prepulse inhibition (PPI) of the acoustic startle response, a measure of sensorimotor gating, can be enhanced by nicotine. Moreover, the TT genotype of the nicotinic acetylcholine receptor (nAChR) α3-subunit (CHRNA3) rs1051730 polymorphism has previously been associated with diminished PPI and nicotine dependence.

OBJECTIVES

We tested whether this CHRNA3 polymorphism also modulates the nicotine-induced enhancement of PPI.

METHODS

We assessed the effect of nicotine on PPI, startle reactivity, and habituation in 52 healthy nonsmoking volunteers genotyped for CHRNA3 rs1051730 in a double-blind, placebo-controlled, counterbalanced, within-subjects design. Additionally, cotinine plasma levels were measured.

RESULTS

Nicotine significantly enhanced PPI in TT homozygotes only and tended to worsen PPI in TC and CC carriers. Additionally, nicotine significantly reduced startle habituation.

CONCLUSIONS

The present findings imply that the effect of nicotine on sensorimotor gating is modulated by nAChR α3-subunits. Thus, genetic variation in nicotinic receptor genes might be an important connecting link between early attentional processes and smoking behavior.

Nicotine enhances antisaccade performance in schizophrenia patients and healthy controls

Nicotine has been proposed to be a cognitive enhancer, particularly in schizophrenia patients. So far, the published studies of nicotine effects on antisaccade performance in schizophrenia patients only tested participants who were deprived smokers. Thus, we aimed to test both smoking and non-smoking patients as well as healthy controls in order to extend previous findings. Moreover, we employed a paradigm using standard and delayed trials. We hypothesized that, if nicotine is a genuine cognitive enhancer, its administration would improve antisaccade performance both in smoking and non-smoking participants. A total of 22 patients with schizophrenia (12 smokers and 10 non-smokers) and 26 controls (14 smokers and 12 non-smokers) completed the study. The effects of a nicotine patch (14 mg for smokers, 7 mg for non-smokers) on antisaccade performance were tested in a randomized, double-blind, placebo-controlled, cross-over trial. Schizophrenia patients made significantly more antisaccade errors than controls (p = 0.03). Both patients and controls made fewer antisaccade errors in the delayed trials than in the standard trials (p < 0.0001). Nicotine significantly reduced antisaccade error rate in the standard trials, but not in the delayed trials (p = 0.02). Smoking status did not influence the nicotine effect on antisaccade error rate (p = 0.10) indicating an equal procognitive effect of nicotine in smokers and non-smokers. Overall the present findings indicate that beneficial effects of nicotine on antisaccade performance are not confined to smoking schizophrenia patients. Instead, the findings likely represent genuine nicotine-induced enhancement of cognitive performance.

Simultaneous quantification of nicotine, cotinine, trans-3'-hydroxycotinine, norcotinine and mecamylamine in human urine by liquid chromatography-tandem mass spectrometry

BACKGROUND

Mecamylamine is a nicotine antagonist under investigation in combination with nicotine replacement for smoking treatment.

METHODS

A simple, rapid and reliable liquid chromatography tandem mass spectrometry (LCMSMS) method was developed and validated for quantifying nicotine, cotinine, trans-3'-hydroxycotinine, norcotinine and mecamylamine in human urine. Chromatography was performed on a Synergi PolarRP column with a gradient of 0.1% formic acid and 0.1% formic acid in acetonitrile at 0.25 ml/min with an 8-min total runtime. Analytes were monitored by positive mode electrospray ionization and multiple reaction monitoring mass spectrometry.

RESULTS

Linear dynamic ranges were 1-500 ng/ml for nicotine and norcotinine, 0.5-500 ng/ml for trans-3'-hydroxycotinine, 0.2-500 ng/ml for cotinine, and 0.1-100 ng/ml for mecamylamine; correlation coefficients were consistently greater than 0.99, and all calibrator concentrations were within 20% of target. Extensive endogenous and exogenous interferences were evaluated. At 3 concentrations spanning the linear dynamic range of the assay, mean extraction efficiencies from urine were 55.1-109.1% with analytical recovery (bias) 82.0-118.7% and total imprecision of 0.7-9.1%. Analytes were stable for 24h at room temperature, 72 h at 4 °C, 72 h in autosampler at 15 °C and after three freeze/thaw cycles.

CONCLUSION

This method is useful for monitoring mecamylamine, nicotine and nicotine metabolites in smoking cessation and other clinical nicotine research.

Analysis of alkaloids from different chemical groups by different liquid chromatography methods

Alkaloids are biologically active compounds widely used as pharmaceuticals and synthesised as secondary methabolites in plants. Many of these compounds are strongly toxic. Therefore, they are often subject of scientific interests and analysis. Since alkaloids — basic compounds appear in aqueous solutions as ionized and unionized forms, they are difficult for chromatographic separation for peak tailing, poor systems efficiency, poor separation and poor column-to-column reproducibility. For this reason it is necessity searching of more suitable chromatographic systems for analysis of the compounds. In this article we present an overview on the separation of selected alkaloids from different chemical groups by liquid chromatography thus indicating the range of useful methods now available for alkaloid analysis. Different selectivity, system efficiency and peaks shape may be achieved in different LC methods separations by use of alternative stationary phases: silica, alumina, chemically bonded stationary phases, cation exchange phases, or by varying nonaqueous or aqueous mobile phase (containing different modifier, different buffers at different pH, ion-pairing or silanol blocker reagents). Developments in TLC (NP and RP systems), HPLC (NP, RP, HILIC, ion-exchange) are presented and the advantages of each method for alkaloids analysis are discussed.