Specific detection of anabasine, nicotine, and nicotine metabolites in urine by liquid chromatography-tandem mass spectrometry

Quantitation of Urine Nicotine, Cotinine, and 3-OH-Cotinine by Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)

Nicotine is a naturally occurring and highly addictive chemical used in e-cigarettes, cigarettes, chewing tobacco, and other tobacco products as well as in nicotine replacement therapies. The negative health consequences of using nicotine-containing products are well known. In fact, smoking remains the leading cause of preventable disease, disability, and death in the United States. Measurement of nicotine and its metabolites, cotinine and 3-OH-cotinine, offers an objective method to evaluate nicotine exposure and the associated health risks. In this chapter, we describe a quick and reliable isotope dilution LC-MS/MS method for the quantitation of these three compounds in 60 μL of human urine following a simple sample preparation procedure. Electrospray Ionization (ESI) in positive mode is used to introduce the analytes into the mass spectrometer and quantitation is achieved using Multiple Reaction Monitoring (MRM). The analytical measurable ranges for nicotine and cotinine are 10-2500 ng/mL and 20-5000 ng/mL for 3-OH-cotinine.

Determination of nicotine in newborn meconium by high-Resolution ambient mass spectrometry using wooden-Tip spray

Prenatal exposure to nicotine that are mainly produced from tobacco smoke has been reported to affect infants. Therefore, nicotine exposure is one of important health concerns for newborn screening. Detecting nicotine and its metabolites such as cotinine in meconium were widely used to evaluate the tobacco exposure of pregnancy. In this study, disposable wooden tips were applied for touch sampling of meconium from newborn infants, and then were directly mounted on mass spectrometer (MS) to perform rapid screening of nicotine and cotinine. Choice of extraction/spray solvents was optimized. The limits of detection, reproducibility, linear response for direct analysis of meconium were also investigated. It is found the limits of detection (S/N = 3) to be as low as 0.36 ng/mg and 1.18 ng/mg for nicotine and cotinine, respectively, while the limits of quantitation (S/N = 10) to be 1.19 ng/mg and 3.94 ng/mg for nicotine and cotinine, respectively. The relative standard deviations (RSD) were found to be at 8.4%-19.8% (n = 6) for nicotine and cotinine, a good linear range from 5-500 ng/mL (R ² > 0.99). These analytical performances are well-accepted levels for ambient mass spectrometer analysis. In this study, evaluation of nicotine and cotinine in 22 puerpera volunteers were conducted by the established wooden-tip spray mass spectrometry (WTS-MS). These results showed that wooden-tip spray mass spectrometry would be useful for newborn screening of nicotine and cotinine in meconium with high reproducibility, speed, sensitivity, and specificity. Owing to the use of disposable wooden tips that involves no sample preparation and no chromatographic separation, our results show that wooden-tip spray mass spectrometry is a powerful tool for determination of nicotine in newborn meconium.

A Simple and High-throughput LC-MS/MS Method for Simultaneous Measurement of Nicotine, Cotinine, 3-OH cotinine, Nornicotine, and Anabasine in Urine and its Application in the General Korean Population

Measuring nicotine metabolites is the most objective method for identifying smoke exposure. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) can measure multiple metabolites and is sensitive enough to detect low concentrations of metabolites. Therefore, we developed a simple and high-throughput method for measuring nicotine, cotinine, trans-3'-hydroxycotinine (3-OH cotinine), nornicotine, and anabasine for population-based studies using LC-MS/MS. Each 30 µl of urine sample was diluted with 90 µL of acetonitrile containing five deuterated internal standards. Chromatographic separation used a C18 column and LC-MS/MS analysis was performed with a multiple reaction monitoring mode. The chromatographic run time for each sample was 6.5 min. The method was validated by evaluating selectivity, interference, limit of detection, lower limit of quantification, precision, accuracy, linearity, extraction recovery, matrix effect, and carry-over according to guidelines. Our methods required a short preparation time (about 20 minutes) while simultaneously measuring five markers for smoking status. No endogenous or exogenous interference was found. Our method showed excellent precision and accuracy: within-run CV 2.9-9.4%, between-run CV 4.8-8.7%, and bias -10.1 to 5.3%. Linear dynamic ranges were 1-10,000 ng/mL for nicotine, nornicotine, and anabasine; 2-5,000 ng/mL for cotinine; and 5-15,000 ng/mL for 3-OH cotinine. Extraction recovery was consistent (87-109%) across concentrations. No significant matrix effect or carry-over was observed. The validated method was applied to 849 urine samples. In samples from the 125 current smokers, nicotine, cotinine, 3-OH cotinine, nornicotine, and anabasine were detected in 97.6%, 99.2%, 98.4%, 96.8%, and 87.2%, respectively. No markers were detected in 93.9% of 609 non-smokers. The overlapping detection of multiple markers made it possible to identify smoking status even in current smokers with low concentration of cotinine. Our LC-MS/MS method using a simple sample preparation technique is sensitive and effective for screening of smoking status in the general population.

Automated Trapping Column Exchanger for High-Throughput Nanoflow Liquid Chromatography

As compared to conventional high-performance liquid chromatography (HPLC) techniques, nanoflow HPLC exhibits improved sensitivity and limits of detection. However, nanoflow HPLC suffers from low throughput due to instrument failure (e.g., fitting fatigue and trapping column failure), limiting the utility of the technique for clinical and industrial applications. To increase the robustness of nanoflow HPLC, we have developed and tested a trapping column exchanging robot for autonomous interchange of trapping columns. This robot makes reproducible, automated connections between the active trapping column and the rest of the HPLC system. The intertrapping column retention time is shown to be sufficiently reproducible for scheduled selected reaction monitoring assays to be performed on different trapping columns without rescheduling the selection windows.

Comparison of SemiQuantitative Cotinine Values Obtained by the DRI Immunoassay and Values Obtained by a Liquid Chromatography-Tandem Mass Spectrometry-Based Method: The DRI Immunoassay is Suitable for Screening Purposes Only Because Semiquantitative Values May Be Unreliable

BACKGROUND

DRI cotinine assay is suitable only for screening for cotinine in urine specimens. We studied the reliability of DRI cotinine semiquantitative values by comparing them with the cotinine concentration obtained with a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method.

METHODS

Semiquantitative cotinine concentrations in 39 urine specimens obtained by the DRI immunoassay were compared with cotinine concentrations obtained by LC-MS/MS.

RESULTS

The DRI cotinine assay consistently overestimated cotinine values obtained by the LC/MS/MS method (y = 1.1529 x + 252.24, n = 39, R² = 0.8899) indicating that semiquantitative values obtained using the DRI assay may be unreliable. However, no false-negative results were observed using the DRI assay.

CONCLUSION

DRI cotinine assay is suitable only for screening cotinine in urine specimens.

Quantitation of the Minor Tobacco Alkaloids Nornicotine, Anatabine, and Anabasine in Smokers' Urine by High Throughput Liquid Chromatography-Mass Spectrometry

Nicotine is the most abundant alkaloid in tobacco accounting for 95% of the alkaloid content. There are also several minor tobacco alkaloids; among these are nornicotine, anatabine, and anabasine. We developed and applied a 96 well plate-based capillary LC-tandem mass spectrometry method for the analysis of nornicotine, anatabine, and anabasine in urine. The method was validated with regard to accuracy and precision. Anabasine was quantifiable to low levels with a limit of quantitation (LOQ) of 0.2 ng/mL even when nicotine, which is isobaric, is present at concentrations >2500-fold higher than anabasine. This attribute of the method is important since anatabine and anabasine in urine have been proposed as biomarkers of tobacco use for individuals using nicotine replacement therapies. In the present study, we analyzed the three minor tobacco alkaloids in urine from 827 smokers with a wide range of tobacco exposures. Nornicotine (LOQ 0.6 ng/mL) was detected in all samples, and anatabine (LOQ, 0.15 ng/mL) and anabasine were detected in 97.7% of the samples. The median urinary concentrations of nornicotine, anatabine, and anabasine were 98.9, 4.02, and 5.53 ng/mL. Total nicotine equivalents (TNE) were well correlated with anatabine (r(2) = 0.714) and anabasine (r(2) = 0.760). TNE was most highly correlated with nornicotine, which is also a metabolite of nicotine. Urine samples from a subset of subjects (n = 110) were analyzed for the presence of glucuronide conjugates by quantifying any increase in anatabine and anabasine concentrations after β-glucuronidase treatment. The median ratio of the glucuronidated to free anatabine was 0.74 (range, 0.1 to 10.9), and the median ratio of glucuronidated to free anabasine was 0.3 (range, 0.1 to 2.9). To our knowledge, this is the largest population of smokers for whom the urinary concentrations of these three tobacco alkaloids has been reported.

Evaluation of the effect of nicotine and metabolites on the periodontal status and the mRNA expression of interleukin-1β in smokers with chronic periodontitis

Background and Objective:

Smoking is an important environmental risk factor involved in the causation and progression of periodontal disease. Smoking can impair various components of the host immune response and immune system. The virulence factors of periodontal pathogens stimulate inflammatory cytokine expression by mononuclear cells. IL-1β is the key mediator involved in the pathogenesis and disease progression. Therefore, whole gingival biopsy samples are assessed for this increased expression of IL-1.

Materials and Methods:

29 male subjects’ age and gender matched were divided into three groups based on the periodontal and smoking status (Group A:healthy, Group B: non-smokers suffering from chronic periodontitis, Group C: smokers suffering from chronic periodontitis). Periodontal parameters like plaque index, gingival index, probing pocket depth and clinical attachment level were recorded at baseline and post scaling. The mRNA expression of IL-1β was determined by real time polymerase chain reaction and correlated with the periodontal and smoking status.

Results:

The improvement in the periodontal parameters was statistically significant in the non- smokers (Group B) and there was a 2 fold increase in the mRNA expression in this group. The smokers (Group C) showed lesser improvement in the periodontal parameters and there was an 8 fold increase in the mRNA expression of IL-1β.

Conclusion:

Association of smoking status with periodontal destruction can thus be correlated with the increased mRNA expression of IL-1β in chronic periodontitis patients.

The chemical components of electronic cigarette cartridges and refill fluids: review of analytical methods

INTRODUCTION

To date, several concerns have been raised on the purity of ingredients employed in the manufacturing processes of refill fluids and cartridges, the device functionality, and the quality control of electronic cigarettes. This article reviews analytical methods so far described for the analysis of liquids to detect their chemical components and to investigate the presence of toxicants and carcinogens that can potentially occur as impurities of ingredients or as a consequence of their degradation.

RESULTS AND DISCUSSION

Based on the scientific literature, high-performance liquid chromatography with diode-array detection (HPLC/DAD) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) are most appropriate for determining nicotine and related compounds in fluids and cartridges, whereas LC-MS/MS has been successfully used to determine nitrosamines. Content analyses of glycols have been performed using gas chromatography equipped with flame ionization detector or gas chromatography/mass spectrometry (GC/MS), whereas carbonyl and other volatile organic compounds determinations have been performed by HPLC/DAD and GC/MS, respectively. Content analyses of heavy metals have been performed by inductively coupled plasma optical emission spectroscopy or inductively coupled plasma mass spectrometry. Since new potentially toxic substances may be created during heating, it is also necessary to investigate the chemical composition of generated aerosol. In this case, similar methods applied for tobacco smoke can be adopted.

CONCLUSIONS

A broad range of analytical techniques are available for the detection of constituents and toxicants in e-liquids and cartridges. Analyses of liquids have been performed with pharmacopeia procedures and methods (International Organization for Standardization, Environmental Protection Agency, and American Public Health Association) developed for other matrices but applicable to e-liquids. Because new potentially harmful substances may be produced during heating process, analyses of aerosol are needed to correlate its composition to the chemical components of liquids.

Zinc Sulfate, a Recently Introduced Urinary Adulterant Can Invalidate Urine Cotinine Test Using Immunoassay but Has Less Effect on Liquid Chromatography Combined With Tandem Mass Spectrometry-Based Test

OBJECTIVE

Zinc sulfate is a recently introduced urinary adulterant, which causes false-negative results with immunoassays used for screening drugs of abuse in urine but whether zinc sulfate also could invalidate urine cotinine assay using immunoassay or liquid chromatography combined with mass spectrometry has never been studied.

DESIGN AND METHOD

Four urine pools containing none detected to high levels of cotinine were analyzed using DRI cotinine immunoassay on the Olympus 640 analyzer as well as using liquid chromatography combined with tandem mass spectrometry. Specimens were reanalyzed after supplementing with various amounts of zinc sulfate that are known to invalidate immunoassays used for drugs of abuse testing.

RESULTS

Zinc sulfate in all concentrations studied caused false-negative results using immunoassays, but zinc sulfate also reduced cotinine values by approximately 2.1%-38.4% when analyzed using liquid chromatography combined with mass spectrometry.

CONCLUSIONS

Zinc sulfate caused false-negative cotinine result when DRI immunoassay was used and also had small to moderate impact on liquid chromatography combined with tandem mass spectrometry-based assay for urine cotinine.

Validation of a LC-MS/MS method for quantifying urinary nicotine, six nicotine metabolites and the minor tobacco alkaloids--anatabine and anabasine--in smokers' urine

Tobacco use is a major contributor to premature morbidity and mortality. The measurement of nicotine and its metabolites in urine is a valuable tool for evaluating nicotine exposure and for nicotine metabolic profiling--i.e., metabolite ratios. In addition, the minor tobacco alkaloids--anabasine and anatabine--can be useful for monitoring compliance in smoking cessation programs that use nicotine replacement therapy. Because of an increasing demand for the measurement of urinary nicotine metabolites, we developed a rapid, low-cost method that uses isotope dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS) for simultaneously quantifying nicotine, six nicotine metabolites, and two minor tobacco alkaloids in smokers' urine. This method enzymatically hydrolyzes conjugated nicotine (primarily glucuronides) and its metabolites. We then use acetone pretreatment to precipitate matrix components (endogenous proteins, salts, phospholipids, and exogenous enzyme) that may interfere with LC-MS/MS analysis. Subsequently, analytes (nicotine, cotinine, hydroxycotinine, norcotinine, nornicotine, cotinine N-oxide, nicotine 1'-N-oxide, anatabine, and anabasine) are chromatographically resolved within a cycle time of 13.5 minutes. The optimized assay produces linear responses across the analyte concentrations typically found in urine collected from daily smokers. Because matrix ion suppression may influence accuracy, we include a discussion of conventions employed in this procedure to minimize matrix interferences. Simplicity, low cost, low maintenance combined with high mean metabolite recovery (76-99%), specificity, accuracy (0-10% bias) and reproducibility (2-9% C.V.) make this method ideal for large high through-put studies.

Assessment of nicotine for second hand smoke exposure in some public places in Romania by UPLC-MS

BACKGROUND

Air nicotine monitoring is a well-known procedure for estimation of exposure to second hand smoke. Few research studies were realized in Romania to evaluate environmental tobacco smoke (ETS) exposure of humans in different public places. The levels of airborne nicotine from environmental tobacco smoke and urinary cotinine and nicotine levels of some subjects were analyzed. In order to better implement/enforce the European legislation regarding the interdiction of smoking in the public places the national authorities need a rapid and reliable analytical method to quickly asses the state of the pollution with cigarette smoke of these populated areas.

RESULTS

The nicotine concentration in the air from different types of public buildings was determined. The median concentration of nicotine in the air from 32 pubs where the smoking was allowed was 590 ng · L(-1), comparing with the pubs where the smoking was not permitted (22 locations) where the median concentration of nicotine was only 32 ng · L(-1). Similarly, the median concentration of nicotine in restaurants where the smoking was allowed (23 locations) was 510 ng · L(-1), in comparison with the restaurants where the smoking was prohibited (11 places) where the median value was 19 ng · L(-1). The lowest concentrations of nicotine were found in high schools (8 locations, median concentration 7.4 ng · L(-1)), universities (5 locations, 23 ng · L(-1)) and hospitals (6 locations, 16 ng · L(-1)).

CONCLUSIONS

The method was validated and gave good linearity, precision, accuracy and limit of detection. The buildings included hospitals, high schools, universities, pubs and restaurants. The presence of air nicotine was recorded in all buildings studied. The highest median levels of air nicotine were found in pubs and restaurants. The presence of air nicotine in indoor public buildings indicates weak implementation of the smoke free law in Romania.

Simultaneous determination of cotinine and trans-3-hydroxycotinine in urine by automated solid-phase extraction using gas chromatography-mass spectrometry

A gas chromatography–mass spectrometry method was developed and validated for the simultaneous automated solid-phase extraction and quantification of cotinine and trans-3-hydroxycotinine in human urine. Good linearity was observed over the concentration ranges studied (R² > 0.99). The limit of quantification was 10 ng/mL for both analytes. The limits of detection were 0.06 ng/mL for cotinine (COT) and 0.02 ng/mL for trans-3-hydroxycotinine (OH-COT). Accuracy for COT ranged from 0.98 to 5.28% and the precision ranged from 1.24 to 8.78%. Accuracy for OH-COT ranged from −2.66 to 3.72% and the precision ranged from 3.15 to 7.07%. Mean recoveries for cotinine and trans-3-hydroxycotinine ranged from 77.7 to 89.1%, and from 75.4 to 90.2%, respectively. This analytical method for the simultaneous measurement of cotinine and trans-3-hydroxycotinine in urine will be used to monitor tobacco smoking in pregnant women and will permit the usefulness of trans-3-hydroxycotinine as a specific biomarker of tobacco exposure to be determined. © 2014 The Authors. Biomedical Chromatography published by John Wiley & Sons Ltd.

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.

Nicotine exposure and metabolizer phenotypes from analysis of urinary nicotine and its 15 metabolites by LC-MS

Smokers who inhale less deeply are exposed to lower amounts of the toxic substances present in tobacco smoke. In order to more rigorously assess tobacco smoke exposure, it is necessary to have an accurate method for quantifying nicotine and all of its known metabolites.

METHODS

A stable-isotope dilution LC-MRM/MS assay has been developed for quantification of urinary nicotine and the 15 possible metabolites that could arise from known metabolic pathways. Nicotine, cotinine, trans-3´-hydroxy-cotinine, nicotine-N-oxide, cotinine-N-oxide, nornicotine, norcotinine and 4-hydroxy-4-(3-pyridyl)butanoic acid were quantified by direct analysis. The corresponding glucuronide metabolites were quantified after urine hydrolysis with β-glucuronidase.

RESULTS

Nicotine and all 15 nicotine metabolites were quantified by LC-MRM/MS in most urine samples from 61 tobacco smokers. Urinary nicotine and metabolite concentrations ranged from 7.9 to 337.8 µM (mean 75.5 ± 67.8 µM). Three nicotine metabolizer phenotypes were established as reduced metabolizers (ratio < 8), normal metabolizers (ratio 8-30), and extensive metabolizers (ratio > 30). 4-hydroxy-4-(3-pyridyl)butanoic acid, which has not been quantified previously, was an abundant metabolite in all three phenotypes.

CONCLUSION

Using this assay it will now be possible to determine whether there are relationships between nicotine exposure and/or metabolizer phenotype with exposure to toxic substances that are present in tobacco smoke and/or to biological response biomarkers to tobacco smoking. This will help in identifying individuals at high risk for developing smoking-related diseases as well as those amenable to smoking cessation programs.

Electron ionization mass spectral study of oxo- and thio derivatives of minor tobacco alkaloids

The electron-ionization mass spectra (EI-MS) of oxo- and thio-derivatives of minor tobacco alkaloids and structurally similar piperidine alkaloids, i.e. thiocotinine (1), 2'-oxo-N-methylanabasine (2), 2'-thio-N- methylanabasine (3), 2'-oxoanabasamine (4) and 2'-thioanabasamine (5) are discussed and general fragmentation routes of their molecular cations are proposed. Comparison of the data obtained for 1 with the EI-MS data of metameric metabolites of nicotine: 3'-hydroxycotinine, (A) and 5'-hydroxycotinine, (B) allows a differentiation between these metamers. The data will be useful for the identification of metabolites of alkaloids of these types in biological matrices.

High-throughput simultaneous analysis of five urinary metabolites of areca nut and tobacco alkaloids by isotope-dilution liquid chromatography-tandem mass spectrometry with on-line solid-phase extraction

BACKGROUND

Areca nut and tobacco are commonly used drugs worldwide and have been frequently used in combination. We describe the use of on-line solid-phase extraction and isotope-dilution liquid chromatography-tandem mass spectrometry for the simultaneous measurement of five major urinary metabolites of both areca nut and tobacco alkaloids, namely, arecoline, arecaidine, N-methylnipecotic acid, nicotine, and cotinine.

METHODS

Automated purification of urine was accomplished with a column-switching device. After the addition of deuterium-labeled internal standards, urine samples were directly analyzed within 13 minutes. This method was applied to measure urinary metabolites in 90 healthy subjects to assess areca nut/tobacco exposure. Urinary time course of arecoline, arecaidine, and N-methylnipecotic acid was investigated in five healthy nonchewers after oral administration of areca nut water extracts.

RESULTS

The limits of detection were 0.016 to 0.553 ng/mL. Interday and intraday imprecision were <10%. Mean recoveries of five metabolites in urine were 97% to 114%. Mean urinary concentrations of arecoline, arecaidine, N-methylnipecotic acid, nicotine, and cotinine in regular areca nut chewers also smokers were 23.9, 5,816, 1,298, 2,635, and 1,406 ng/mg creatinine, respectively. Time course study revealed that after administration of areca nuts extracts, the major urinary metabolite was arecaidine with a half-life of 4.3 hours, followed by N-methylnipecotic acid with a half-life of 7.9 hours, and very low levels of arecoline with a half-life of 0.97 hour.

CONCLUSIONS

This on-line solid-phase extraction liquid chromatography-tandem mass spectrometry method firstly provides high-throughput direct analysis of five urinary metabolites of areca nut/tobacco alkaloids.

IMPACT

This method may facilitate the research into the oncogenic effects of areca nut/tobacco exposure.

A novel validated procedure for the determination of nicotine, eight nicotine metabolites and two minor tobacco alkaloids in human plasma or urine by solid-phase extraction coupled with liquid chromatography-electrospray ionization-tandem mass spectrometry

A novel validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) procedure was developed and fully validated for the simultaneous determination of nicotine-N-beta-D-glucuronide, cotinine-N-oxide, trans-3-hydroxycotinine, norcotinine, trans-nicotine-1'-oxide, cotinine, nornicotine, nicotine, anatabine, anabasine and cotinine-N-beta-D-glucuronide in human plasma or urine. Target analytes and corresponding deuterated internal standards were extracted by solid-phase extraction and analyzed by LC-MS/MS with electrospray ionization (ESI) using multiple reaction monitoring (MRM) data acquisition. Calibration curves were linear over the selected concentration ranges for each analyte, with calculated coefficients of determination (R(2)) of greater than 0.99. The total extraction recovery (%) was concentration dependent and ranged between 52-88% in plasma and 51-118% in urine. The limits of quantification for all analytes in plasma and urine were 1.0 ng/mL and 2.5 ng/mL, respectively, with the exception of cotinine-N-beta-D-glucuronide, which was 50 ng/mL. Intra-day and inter-day imprecision were < or = 14% and < or = 17%, respectively. Matrix effect (%) was sufficiently minimized to < or = 19% for both matrices using the described sample preparation and extraction methods. The target analytes were stable in both matrices for at least 3 freeze-thaw cycles, 24 h at room temperature, 24 h in the refrigerator (4 degrees C) and 1 week in the freezer (-20 degrees C). Reconstituted plasma and urine extracts were stable for at least 72 h storage in the liquid chromatography autosampler at 4 degrees C. The plasma procedure has been successfully applied in the quantitative determination of selected analytes in samples collected from nicotine-abstinent human participants as part of a pharmacokinetic study investigating biomarkers of nicotine use in plasma following controlled low dose (7 mg) transdermal nicotine delivery. Nicotine, cotinine, trans-3-hydroxycotinine and trans-nicotine-1'-oxide were detected in the particular sample presented herein. The urine procedure has been used to facilitate the monitoring of unauthorized tobacco use by clinical study participants at the time of physical examination (before enrollment) and on the pharmacokinetic study day.

Quantitation of nicotine, its metabolites, and other related alkaloids in urine, serum, and plasma using LC-MS-MS

We describe a method for the quantitative analysis of nicotine, cotinine, trans-3'-hydroxy cotinine, nornicotine, and anabasine in urine, serum, and plasma using liquid chromatography-tandem mass spectrometry. A mix of deuterium-labeled internal standards (IS) is added to a specimen aliquot. The aliquot is extracted using mixed-mode solid phase extraction and eluted into an autosampler vial for injection into an LC-MS-MS system. An Atlantis silica column is used for LC separation in hydrophilic interaction mode. Tandem mass spectrometry detection is performed in positive ion mode with electrospray ionization and two multiple reaction monitoring (MRM) transitions monitored for each analyte and IS.

Optimization and validation of a liquid chromatography-tandem mass spectrometry method for the simultaneous quantification of nicotine, cotinine, trans-3'-hydroxycotinine and norcotinine in human oral fluid

An analytical procedure was developed and validated for the simultaneous identification and quantification of nicotine, cotinine, trans-3'-hydroxycotinine, and norcotinine in 0.5 mL of human oral fluid collected with the Quantisal oral fluid collection device. Solid phase extraction and liquid chromatography-tandem mass spectrometry with multiple reaction monitoring were utilized. Endogenous and exogenous interferences were extensively evaluated. Limits of quantification were empirically identified by decreasing analyte concentrations. Linearity was from 1 to 2,000 ng/mL for nicotine and norcotinine, 0.5 to 2,000 ng/mL for trans-3'-hydroxycotinine, and 0.2 to 2,000 ng/mL for cotinine. Correlation coefficients for calibration curves were >0.99 and analytes quantified within +/-13% of target at all calibrator concentrations. Suitable analytical recovery (>91%) was achieved with extraction efficiencies >56% and matrix effects <29%. This assay will be applied to the quantification of nicotine and metabolites in oral fluid in a clinical study determining the most appropriate nicotine biomarker concentrations differentiating active, passive, and environmental nicotine exposure.

Isopropanol protein precipitation for the analysis of plasma free metanephrines by liquid chromatography-tandem mass spectrometry

BACKGROUND

High-performance liquid chromatography-tandem mass spectrometric (LC-MS/MS)1 analysis of plasma free metanephrines is the most diagnostically sensitive and specific screening test for the diagnosis of pheochromocytoma. We sought to develop an in-house method for this expensive test

METHODS

We used off-line isopropanol protein precipitation of plasma to remove interfering substances before LC-MS/MS analysis. We compared the extraction efficiency and limits of quantification of protein precipitation to those of previously reported solid-phase techniques.

RESULTS

The new method had limits of quantification of 0.09 nmol/L and 0.17 nmol/L for metanephrine and normetanephrine, respectively. Method comparison with a previously described solid-phase extraction method revealed Deming regression slopes of 0.904 and 0.994, intercepts of 0.007 and 0.023, and SEs of the residuals (S(y/x)) of 0.071 and 0.284 for metanephrine and normetanephrine, respectively. Extraction efficiency of isopropanol protein precipitation was 66% for metanephrine and 35% for normetanephrine, results that were superior to the efficiencies of 4% and 1% for our adapted solid-phase extraction method. No ion suppression was observed at the retention times for metanephrine and normetanephrine.

CONCLUSIONS

Isopropanol protein precipitation is a novel and effective off-line sample preparation method for metanephrines that offers a less expensive alternative to on-line solid-phase extraction for low-volume testing and requires a sample volume of only 200 microL. The mass spectrometric analysis time is equivalent to that of solid-phase techniques.

Quantification of nicotine, cotinine, trans-3'-hydroxycotinine, nornicotine and norcotinine in human meconium by liquid chromatography/tandem mass spectrometry

There are no analytical methods that simultaneously quantify nicotine, cotinine, trans-3'-hydroxycotinine, nornicotine and norcotinine in human meconium. Such a method could improve identification of in utero tobacco exposure, determine if maternal dose-meconium concentration relationships exist, and whether nicotine meconium concentrations predict neonatal outcomes. The first liquid chromatography/atmospheric pressure chemical ionization tandem mass spectrometry method for simultaneous quantification of these analytes in meconium was developed and validated. Specimen preparation included homogenization, enzyme hydrolysis and solid phase extraction. The linear range was 1.25 or 5-500ng/g. Method applicability was evaluated with meconium collected from an in utero tobacco exposed infant.

Analysis of [3',3'-d(2)]-nicotine and [3',3'-d(2)]-cotinine by capillary liquid chromatography-electrospray tandem mass spectrometry

A selective and sensitive LC/MS/MS assay was developed for the quantification of d(2)-nicotine and d(2)-cotinine in plasma of current and past smokers administered d(2)-nicotine. After solid phase extraction and liquid-liquid extraction, HPLC separation was achieved on a capillary hydrophilic interaction chromatography phase column. The analytes were monitored by tandem mass spectrometry with electrospray positive ionization. Linear calibration curves were generated for d(2)-nicotine (0.03-6.0 ng/ml plasma) and d(2)-cotinine (0.15-25 ng/ml plasma). The lower limits of quantitation were 0.15 ng/ml and 0.25 ng/ml for d(2)-nicotine and d(2)-cotinine, respectively. The coefficient of variation was 3.7% for d(2)-nicotine and 2.5% for d(2)-cotinine. The method was applied to two ongoing studies of d(2)-nicotine metabolism in prior and current smokers. Preliminary analysis of a subset of subjects from these studies detected a significantly lower rate of nicotine conversion to cotinine by past smokers compared to current smokers.