Simultaneous determination of nicotine, cotinine and five additional nicotine metabolites in the urine of smokers using pre-column derivatisation and high-performance liquid chromatography

Effects of Medicinal Herb Tea on the Smoking Cessation and Reducing Smoking Withdrawal Symptoms

Medicinal herbs (21 species) were screened for the antioxidant activity and nicotine degradation activity (NDA) in vitro. Eleven of them with higher antioxidant activity and NDA were selected for preparation of the medicinal herb tea (MHT) and the effects of MHT on smoking cessation and reducing smoking withdrawal symptoms were evaluated in 100 male human smokers.

Among these medicinal herbs, Eugenia aromaticum and Astragalus membranaceus Bunge showed the highest antioxidant activity ( IC 50 of 30.0 μg/mL) and NDA (1.81), respectively. MHT showed relatively high antioxidant activity ( IC 50 of 50.6 μg/mL) and NDA (1.23). The urinary cotinine level, a metabolite of nicotine, increased in the first 2 weeks and greatly decreased from the 2nd to 4th week in the MHT taking group, which indicates that MHT accelerates the conversion of nicotine into cotinine. Human groups taking MHT for 4 weeks underwent reduced smoking withdrawal symptoms compared to the non-MHT taking subjects, and 38% of subjects taking MHT succeeded in smoking cessation, while only 12% of non-MHT taking subjects succeeded in quitting smoking.

Metabolism of myosmine in Wistar rats

The alkaloid myosmine is present not only in tobacco products but also in various foods. Myosmine is easily nitrosated, yielding 4-hydroxy-1-(3-pyridyl)-1-butanone (HPB) and the esophageal tobacco carcinogen N'-nitrosonornicotine. Due to its widespread occurrence, investigations on the metabolism and activation of myosmine are needed for risk assessment. Therefore, the metabolism of myosmine has been studied in Wistar rats treated with single oral doses of [pyridine-5-3H]myosmine at 0.001, 0.005, 0.5, and 50 micromol/kg body weight. Oral administration was achieved by feeding a labeled apple bite. Radioactivity was completely recovered in urine and feces within 48 h. At the two lower doses, 0.001 and 0.005 micromol/kg, a higher percentage of the radioactivity was excreted in urine (86.2 +/- 4.9% and 88.9 +/- 1.7%) as compared with the higher doses, 0.5 and 50 micromol/kg, where only 77.8 +/- 7.3% and 75.4 +/- 6.6% of the dose was found in urine. Within 24 h, urinary excretion of radioactivity was nearly complete with less than 4% of the total urinary output appearing between 24 and 48 h. The two major metabolites accounting for >70% of total radioactivity in urine were identified as 3-pyridylacetic acid (20-26%) and 4-oxo-4-(3-pyridyl)butyric acid (keto acid, 50-63%) using UV-diode array detection and gas chromatography-mass spectrometry measurements. 3-Pyridylmethanol (3-5%), 3'-hydroxymyosmine (2%) and HPB (1-3%) were detected as minor metabolites. 3'-Hydroxymyosmine is exclusively formed from myosmine and therefore might be used as a urinary biomarker for myosmine exposure in the future.

Measuring tobacco smoke exposure: quantifying nicotine/cotinine concentration in biological samples by colorimetry, chromatography and immunoassay methods

Procedures to assess tobacco smoke exposure are reviewed and biomarkers used for determining the smoking status of an individual are compared. Methods used to extract these biomarkers from saliva, urine, and blood and the advantages and disadvantages of the assays are discussed. Finally, the procedures used to measure the levels of cortisol, a stress hormone speculated to be linked to nicotine metabolism, are discussed.

Determination of nicotine and cotinine in tobacco harvesters’ urine by solid-phase extraction and liquid chromatography

A solid-phase extraction method using Drug Test-1 column containing chemically modified silica as a solid support for sample clean up and reversed phase ion-paired high-pressure liquid chromatography method have been developed for the simultaneous determination of nicotine and its metabolite cotinine from the urine samples. Mobile phase was consisted of acetate buffer (containing 0.03 M sodium acetate and 0.1 M acetic acid) pH 3.1 and acetonitrile (78:22% (v/v)) containing 0.02 M sodium octanosulfonate as an ion pair agent. pH of the mobile phase was adjusted to 3.6 with triethylamine for better resolution and to prevent peak tailing. The linearity was obtained in the range of 0.5-10 microg/ml concentrations of nicotine and cotinine standards. The correlation coefficients were 0.998 for cotinine and 0.999 for nicotine. The recoveries were obtained in the range of 79-97% with average value of 85% for nicotine and in the range of 82-98% with average value of 88% for cotinine. The limit of detection was 2 ng/ml for cotinine and 5 ng/ml for nicotine with 2 ml urine for extraction, calculated by taking signal to noise ratio 10:3. The intra-day co-efficient of variation (CV) were <4 and 7% and inter-day CV were <9 and 7% for nicotine and cotinine, respectively. The method was applied to the urine samples of tobacco harvesters, who suffer from green tobacco sickness (GTS) to check the absorption of nicotine through dermal route during the various processes of tobacco cultivation due to its good reproducibility and sensitivity.

Exposure related mutagens in urine of rubber workers associated with inhalable particulate and dermal exposure

AIMS

To determine the relation of the inhalation and dermal exposure routes and mutagenic activity in the urine of rubber workers (n = 105).

METHODS

Mutagenic activity of ambient total suspended particulate matter (TSPM), surface contamination wipes, and Sunday and weekday urine samples was assessed with S typhimurium YG1041 in the presence of a metabolic activation system. Each subject was grouped into one of two exposure categories for dermal exposure (high (>/=25 revertants/cm(2)), low (<25 revertants/cm(2))) based on the mutagenic activity detected on likely skin contact surfaces and into two airborne mutagenic exposure categories (high (>/=210 revertants/m(3)), low (<210 revertants/m(3))). The potential influence of skin aberrations and acetylation status (NAT2) on urinary mutagenicity levels was also evaluated.

RESULTS

A non-significant increase of +1605 revertants/g creatinine in urinary mutagenicity during the workweek relative to levels observed on Sunday was observed for the total population. Subsequent multivariate regression analyses, with the subjects' weekday urinary mutagenicity levels as the dependent variable, revealed associations with environmental and mainstream tobacco smoke exposure, with the level of mutagenic contamination on surfaces with which the subjects had likely contact, with the subjects' inhalable particulate exposure level, with observed mild skin aberrations, and when the subjects had a slow acetylation phenotype. Similar associations, although weaker were observed with Sunday urinary mutagenicity levels as well, except for the association with slow acetylation phenotype. Based on measured exposure levels it could be estimated that a high potential for exposure to surface contamination with mutagenic activity increased weekday urinary mutagenicity by about 62% when compared to low exposed workers, while high inhalable particulate exposure levels increased weekday urinary mutagenicity levels by about 21%. Subjects with mild skin aberrations had an additional, non-significant, increase in weekday urinary mutagenic activity compared to subjects without any skin aberrations.

DISCUSSION

Results suggest that the dermal exposure route may contribute more to the level of genotoxic compounds in urine of rubber workers than the inhalation route. Although the study was limited in size, the results warrant further investigation in the importance of and ways to effectively control the dermal exposure route in the rubber industry.

Determination of Nicotine and Its Major Metabolite Cotinine in Plasma or Serum by Gas Chromatography-Mass Spectrometry Using Ion-Trap Detection

A specific method has been developed for the quantitative determination of nicotine and its major metabolite cotinine in plasma or serum of active and passive smokers. Deuterium-labelled nicotine and cotinine were used as internal standards. The amounts of nicotine and cotinine present in a sample of plasma or serum were extracted with a simple extraction procedure (liquid-liquid or solid-phase extraction). The extracts were analysed by gas chromatography coupled with mass spectrometry using ion-trap detection. The analysis was done in positive chemical ionisation with methanol as the liquid reagent. The method has been demonstrated to be linear up to 1000 microg/l. Limits of quantification for nicotine and cotinine are 10 and 5 microg/l, respectively with liquid-liquid extraction, and 1 microg/l for each of the compounds with solid-phase extraction. The present method has been applied to several real cases.

Urothelial cell DNA adducts in rubber workers

Workers employed in the rubber industry appear to have a significant excess cancer risk in a variety of sites, including cancer of the urinary bladder. In this cross-sectional study, we investigated the occurrence of DNA adducts in exfoliated bladder cells of currently exposed, nonsmoking rubber workers (n = 52) and their relationship with occupational exposure estimates and acetylation phenotype (NAT2). Four DNA adducts were identified, with the proportion of positive samples (e.g., DNA samples with quantifiable levels of a specific DNA adduct) ranging from 3.8 to 79%. The highest proportion of positive samples and the highest relative adduct labeling levels were in workers involved in the production functions "mixing" and "curing," areas with potential for substantial exposure to a wide range of chemical compounds used in rubber manufacturing (P < 0.05 for adducts 2 and/or 3, compared to all other departments). No statistically significant relationships were found between identified DNA adducts and urinary mutagenicity or personal inhalable and dermal exposure estimates. Interestingly, subjects with a fast NAT2 acetylation phenotype tended to have higher levels of DNA adducts. This study suggests that rubber workers engaged in mixing and curing may be exposed to compounds that can form DNA adducts in urothelial cells. Larger studies among rubber workers should be conducted to study in more detail the potential carcinogenicity of exposures encountered in these work areas.

Separation of nicotine metabolites by capillary zone electrophoresis and capillary zone electrophoresis/mass spectrometry

The use of capillary zone electrophoresis (CZE) and capillary zone electrophoresis/mass spectrometry (CZE/MS) has been demonstrated, in principle, for the separation of nicotine and nicotine metabolites. The buffer system developed for separation and detection by CZE/UV was modified for use in CZE/MS analysis. Several of the metabolites are isobaric and tandem mass spectrometric (MS/MS) techniques have been used to differentiate such analytes.

Improved highly sensitive method for determination of nicotine and cotinine in human plasma by high-performance liquid chromatography

A highly sensitive and reliable method for the determination of nicotine and its metabolite cotinine in human plasma by high-performance liquid chromatography was developed. Nicotine and cotinine were extracted from alkalinized plasma with dichloromethane and the volatility of nicotine was prevented by the addition of conc. HCl to the organic solvent during evaporation. The sensitivity of quantification at 260 nm absorption was improved by using a noise-base clean Uni-3 to 0.2 ng/ml nicotine and 1.0 ng/ml cotinine. The method was validated over linear ranges of 0.2-25.0 ng/ml for nicotine and 1.0-80.0 ng/ml for cotinine. The intra-day precision and accuracy were < or = 15.9% relative standard variation (RSD) and 89.9-103.5% for nicotine and < or = 8.0% RSD and 98.7-103.0% for cotinine. The inter-day precision and accuracy were < or = 17.0% RSD and 94.2-100.9% for nicotine and < or = 8.2% RSD and 98.0-105.1% for cotinine.

Analysis of Nicotine, 3-Hydroxycotinine, Cotinine, and Caffeine in Urine of Passive Smokers by HPLC-Tandem Mass Spectrometry

Background: A method is described for the simultaneous analysis of nicotine and two of its major metabolites, cotinine and 3-hydroxycotinine, as well as for caffeine from urine samples. The method was developed to assess exposure of restaurant and hotel workers to environmental tobacco smoke.

Methods: The method includes sample pretreatment and reversed-phase HPLC separation with tandem mass spectrometric identification and quantification using electrospray ionization on a quadrupole ion trap mass analyzer. Sample pretreatment followed standard protocols, including addition of base before liquid-liquid partitioning against dichloromethane on a solid matrix, evaporation of the organic solvent using gaseous nitrogen, and transferring to HPLC vials using HPLC buffer. HPLC separation was run on-line with the electrospray ionization-tandem mass spectrometric detection.

Results: The detection limits of the procedure were in the 1 μg/L range, except for nicotine (10 μg/L of urine). Still lower detection limits can be achieved with larger sample volumes. Recoveries of the sample treatment varied from 99% (cotinine) to 78% (3-hydroxycotinine).

Conclusions: The method described is straightforward and not labor-intensive and, therefore, permits a high throughput of samples with excellent prospects for automation. The applicability of the method was demonstrated in a small-scale study on restaurant employees.

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A solid phase extraction method for determination of nicotine in serum and urine by isotope dilution gas chromatography/mass spectrometry with selected ion monitoring

A rapid method for measuring nicotine concentration in serum and urine is described. Deuterated nicotine is used as an internal standard. Nicotine and deuterated nicotine are extracted using a copolymeric-bonded phase silica column. The extract is analysed by gas chromatography coupled with mass spectrometry (GC/MS) operating in selected ion monitoring mode. The method has a lower limit of detection of approximately 2 micrograms/L and is linear to at least 2000 micrograms/L. Within-run percentage coefficients of variation (% CV) are < 4 in both assays over a nicotine concentration range of 10-2000 micrograms/L. Between-run % CV in the serum assay are 5.4, 5.2, 4.8 and 5.9, respectively, at nicotine concentrations of 10, 15, 25, and 50 micrograms/L. Between-run % CV in the urine assay are 5.9, 4.5, 2.7 and 5.2, respectively, at nicotine concentrations of 100, 250, 500, and 2000 micrograms/L. The absolute recovery of nicotine is 61 +/- 6% (mean +/- SD) over the range of 10-250 micrograms/L. The assay has been used to measure serum nicotine concentrations and 24-h urinary excretion of nicotine to monitor the extent of replacement in subjects receiving transdermal nicotine therapy for smoking cessation.

Determination of nicotine, cotinine and caffeine in meconium using high-performance liquid chromatography

A high-performance liquid chromatographic method with diode-array detection for the determination of nicotine and its metabolites, cotinine and caffeine, in meconium is described. This method is suitable to assess foetus exposure to tobacco smoke. The analytes were extracted by solid-phase extraction before chromatography. From among 30 meconium samples 11 were positive for cotinine (20-86 ng/g) and 27 for caffeine (10-45 ng/g). No nicotine was present in the samples because of its rapid metabolism into cotinine.

Use of Salmonella typhimurium TA 98, YG 1024 and YG 1021 and deconjugating enzymes for evaluating the mutagenicity from smokers' urine

Four smokers were chosen for their different smoking habits, and their declared cigarette consumption confirmed by urinary measurement of nicotine and its metabolites. The promutagenicity of their urine was evaluated by the Ames test, modified according to Kado et al. (Mutation Res., 31 (1983)25-32) after extraction on XAD2 Amberlite resin. The different Salmonella typhimurium strains TA 98, YG 1021 and YG 1024 were compared to determine the presence of amino aromatic compounds in the urine of smokers of blond and black tobacco. The strain YG 1024 shows higher mutagenicity than TA 98 for extracts from the smoker's urine and more particularly from black tobacco smokers. In addition, the pretreatment of urine by external enzymatic systems (beta-glucuronidase or arylsulfatase) reveals the presence in the urine of glucurono- and sulfoconjugated forms of promutagens, including amino aromatic compounds.

Urinary promutagens of smokers: comparison of concentration methods and relation to cigarette consumption

Different extraction techniques can be used to concentrate the promutagens of cigarette smokers' urine before evaluation of their mutagenic potency by Ames test. In this study, three solid adsorbents, C18, XAD2 and CN were compared for their ability to concentrate the promutagens of smokers' urine prior to acetone elution. C18 extracts were observed to have a higher promutagenicity than XAD2 and CN extracts. The mutagenicity of smokers' urine depended on the smoking habits, and a strong correlation was observed between urinary promutagenicity, daily cigarette consumption, and the tobacco type (black or blond). Smokers of black tobacco had a higher urinary genotoxicity than smokers of blond tobacco, after taking into account the level of tobacco consumption. Urinary promutagenicity did not appear to depend on the tar level of cigarettes.

Behavioral anti-smoking trial in chronic obstructive pulmonary disease patients

Smoking causes chronic obstructive pulmonary disease (COPD), but few controlled studies have tested anti-smoking treatments in COPD. With procedures likely to attract unmotivated persons we recruited 49 quite-ill, smoking COPD patients. During one or two daily home visits for 85 days, breath carbon monoxide (CO) and self-reports of daily smoking were obtained. Patients, given quit dates and nicotine gum (2-mg pieces, up to 30 per day), were assigned randomly to three groups: Experimentals were reinforced with lottery tickets for CO < 10 ppm. Cigarette Self Report (CSR) patients were reinforced for reporting no smoking that day. Controls received non-contingent payments. Each group's mean CO level fell at the quit date. Thereafter, reinforced patients maintained significantly lower CO levels than Controls. Although many more 24-h abstentions occurred in the intervention period than in baseline, few patients sustained abstinence; the groups did not differ in that regard. Outcome was predicted by decisions to throw away cigarettes when intervention began, but not by motivation scales nor Fagerstrom dependence scores. Pay schedules apparently exaggerated self-reports of reduced smoking. Although results are statistically significant, there is still no proven, practical treatment for smoking in advanced COPD.

Variables affecting nicotine metabolism

Nicotine metabolism is exceedingly sensitive to perturbation by numerous host factors. To reduce the large variations and discrepancies in the literature pertaining to nicotine metabolism, investigators in future studies need to recognize and better control these host factors. Recent advances in the understanding of nicotine metabolism have suggested new approaches to elucidating underlying mechanisms of certain toxic effects associated with cigarette smoking.

Simple high-performance liquid chromatographic method to verify the direct barbituric acid assay for urinary cotinine

An isocratic HPLC method is described to determine urinary concentrations of nicotine and cotinine after derivatization with cyanogen chloride and barbituric acid. This method has been used to assess the reliability of the direct barbituric acid assay to determine smoking status. It is concluded that the direct barbituric acid assay is a very reliable indicator of smoking status, provided that urine blank samples are prepared to correct for background absorbance. If the direct barbituric acid assay is in disagreement with self-reported smoking status, this HPLC procedure is a useful method to resolve the discrepancy.

Femtogram on-column detection of nicotine by isotope dilution gas chromatography/negative ion detection mass spectrometry

A gas chromatographic method, utilizing detection by negative chemical ionization (NCI) mass spectrometry, is presented for the detection of nicotine. The method incorporates derivatization with heptafluorobutyric anhydride/pyridine to yield the ring-opened addition product, 1-[4-(3'-pyridyl)-4-heptafluorobutyryloxybutyl]-1- methylheptafluorobutanamide. The resulting heptafluorobutanamide is both relatively stable and an excellent electron scavenger. This methodology provides for the detection of nicotine at femtogram on-column levels, the measurement of nicotine over three orders of magnitude, and the minimization of contamination due to environmental nicotine.

Comparison of a mechanized version of the 'König' reaction and a fluorescence polarization immunoassay for the determination of nicotine metabolites in urine

Smoking can be detected by the determination of cotinine in urine. We compared the performance of an automated modification of the 'König' reaction adapted to a centrifugal analyzer with an automated commercial fluorescence polarization immunoassay (TDX system). In the latter assay, cotinine, as the primary metabolite of nicotine, can be measured with high specificity. In contrast, the 'König' reaction also detects nicotine metabolites other than cotinine by a group colour reaction. Analysis speed of the 'König' reaction was about 66 samples/h with a detection limit 2 S.D. above the mean value of urine samples of non-smokers. Analysis speed of the TDX system was 41 samples/h. The coefficient of variation (C.V.) of both methods in smokers' urine was 8.6% ('König' reaction) vs. 3.4% (TDX system) in the high range and 16.4% vs. 9.5% in the low range. In a controlled, prospective study recruiting 86 cigarette-smoking volunteers, 83.7% were correctly classified as being smokers by both systems, 13.9% were classified as smokers by the 'König' reaction only and 2.4% were misclassified as non-smokers by both systems. Thus, the sensitivity of the 'König' reaction seems to be higher than in the TDX system (97.6% vs. 83.7%). Of 33 non-smoking individuals, 81.8% were correctly classified as non-smokers by both systems, 18.2 were misclassified as smokers by the 'König' reaction and no person was misclassified by the fluorescence polarization immunoassay. Thus, the specificity of the TDX system seems to be higher than that of the 'König' reaction (100% vs. 81.8%). We conclude that both systems are applicable to detect individuals who smoke regularly by simple urine testing. The higher specificity of the TDX system is outweighed by the higher sensitivity of the 'König' reaction at much lower cost.

Chemical analyses as validators in smoking cessation programs

This review addresses the use of chemical analyses to validate the smoking status of a participant in a smoking cessation program. Pharmacokinetic and chemical validation literature leads to the conclusion that chemical analyses are most reliably used to confirm abstinence from smoking rather than as quantitative measures of nicotine intake or smoking activity. Analytical methodologies used in smoking validation studies are reviewed with their advantages and disadvantages. Close collaboration of behavioral scientists and analytical chemists is encouraged to validate the smoking status of participants in a smoking cessation program.

High-performance liquid chromatographic determination of nicotine and its urinary metabolites via their 1,3-diethyl-2-thiobarbituric acid derivatives

The 1,3-diethyl-2-thiobarbituric acid (DETBA) assay for nicotine metabolites has been improved so that it can be used to determine the concentrations of nicotine and up to 12 metabolites in the urine of humans and laboratory animals, including phase 2 metabolites. The products of beta-glucuronidase cleavage found in human urine were mainly trans-3'-hydroxycotinine, cotinine, and a small amount of nicotine. Following isolation, spectroscopic analyses showed the structure of the nicotine DETBA derivative to be the one-to-one ring-opening product of DEBTA and the cyanopyridinium salt of nicotine.

Determination of nicotine and two major metabolites in serum by solid-phase extraction and high-performance liquid chromatography, and high-performance liquid chromatography-particle beam mass spectrometry

A rapid and selective assay of nicotine, cotinine and trans-3'-hydroxycotinine in human serum, based on high-performance liquid chromatography with UV detection has been developed. The compounds were subjected to solid-phase extraction, using Extrelut 1 cartridges. Recoveries were ca. 95% for nicotine, 90% for cotinine and 50-55% for trans-3'-hydroxycotinine. The limit of quantitation observed with this method was 10 ng/ml for nicotine and 5 ng/ml for each of the metabolites. The compounds were also identified using high-performance liquid chromatography with particle beam mass spectrometry, to confirm their presence in human serum.

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.

Simultaneous determination of cotinine and trans-3'-hydroxycotinine in human serum by high-performance liquid chromatography

A high-performance liquid chromatographic method with ultraviolet photometric detection has been developed for the quantitation of cotinine and trans-3'-hydroxycotinine in human serum. A solid-phase extraction procedure was performed for the analytes and the internal standard, N-ethylnorcotinine, before chromatography. The use of a 30-cm reversed-phase column and a mobile phase of water-methanol-0.1 M sodium acetate-acetonitrile (67:24.5:6.5:2, v/v), pH 4.3, prevented the co-elution of caffeine with cotinine. The limit of quantitation observed with this method was 5 ng/ml for both cotinine and trans-3'-hydroxycotinine. The present method proved useful for the determination of serum levels of these metabolites, correlating with nicotine daily intake.

Identification of cis-3'-hydroxycotinine as a urinary nicotine metabolite

1. cis-3'-Hydroxycotinine was detected as an S(-)-nicotine metabolite in the urine of smokers as well as in the urine of rats and hamsters dosed with nicotine. 2. The excreted amount of cis-3'-hydroxycotinine is lower than that of the trans-isomer.