Determination Of Cotinine Research Articles

Plasma nicotine and its metabolite as biomarkers of tobacco exposure and their relevance to pulmonary nodule.

Aim: Explore the optimal cut-off values for plasma nicotine and its metabolites in assessing smoking status and quantify the association between individual tobacco exposure and pulmonary nodules (PNs).Materials & methods: A total of 2245 plasma samples were included for the determination of nicotine (Nic), cotinine (Cot) and trans-3'-hydroxycotinine (OHCot) concentrations. The receiver operating characteristic curve was used to determine the optimal biomarkers reflecting smoking status. Binary logistic regression, restricted cubic spline and generalized linear model were used to analyze the association of nicotine and its metabolites with PNs. Quantile g-computation was used to investigate the mixed effects between them.Results: Cot was found to be the best biomarker of self-reported active-passive smoking, with optimal thresholds of 9.06 and 1.26ng/ml, respectively. Except for OHCot, increased concentrations of Cot, Nic, total nicotine equivalent (TNE2) and TNE3 were significantly positively associated with the risk of PNs, whereas nicotine metabolite ratio presented a negative association. The mixed effects of OHCot, Cot and Nic were associated with PNs, with an odds ratio of 1.17 and a 95% CI of 1.05-1.30.Conclusion: Nicotine and its metabolites as potential biomarkers of tobacco exposure were significantly associated with PNs.

Determination of Cotinine, 3'-Hydroxycotinine and Nicotine 1'-Oxide in Urine of Passive and Active Young Smokers by LC-Orbitrap-MS/MS Technique.

Tobacco smoke is probably the most significant factor conducing to toxic xenobiotics exposure to humans. The aim of the study was to develop a rapid and sensitive method for the determination of selected nicotine metabolites in urine of tobacco smokers and passive smokers. The method for removing protein and extracting the metabolites involved the centrifugation of urine with acetonitrile. Cotinine, trans-3'-hydroxycotinine, and (2'S)-nicotine 1'-oxide in the supernatant were determined using the LC-Orbitrap-MS/MS technique, with the selected ion monitoring (SIM) and parallel reaction monitoring (PRM) modes used. The recovery of these analytes added to the urine samples ranged from 72% to 101%. Repeatability and reproducibility were less than 3.1% and 10.1%, respectively. The study was carried out among medical students. The group was selected as representatives of young people and who as future physicians should be more aware of the effects of nicotine use. Concentration levels of cotinine and trans-3'-hydroxycotinine determined in ng/mL in the urine of cigarette smokers were 70- and 58-fold higher, respectively, compared to passive smokers. Higher concentrations were recorded in the urine of those passively exposed to tobacco smoke than in non-smokers, confirming that passive exposure to tobacco smoke is not harmless to the human body. However, no significant differences were observed in the concentration of (1'S,2'S)-nicotine 1'-oxide in the samples of individuals from various groups.

Gas chromatography-mass spectrometry determination of nicotine and cotinine in urine: A study of the effect of passive smoking.

Recent data suggest that passive smoking has a risk comparable to active smoking. Passive smoking is considered dangerous in children and is suspected as a cause of asthma. However, some reports are opposing such claims, indicating the need for solid results and large-scale studies. This scientific work aims to develop a method for the determination of nicotine (NCOT) and major nicotine's metabolite cotinine (COT) in urine samples, using gas chromatography-mass spectrometry (GC-MS). Analysis was performed using a gas chromatograph Agilent Technologies 7890A with an MS 5975C inert XL, EI/CI MSD with Triple-Axis detector. For sample preparation, liquid-liquid extraction was applied after an optimization study with different extraction media. Eventually, 1 mL of dichloromethane was selected for the extraction of 0.5mL of urine. Suitable chromatographic conditions were found for the rapid and accurate determination of NCOT and COT. Injection of 2μL was performed using GC-MS, and selected ion monitoring (SIM) analysis was performed with the following ions (m/z): 162 (quantifier ion) and 84, 133, 161 qualifier ions for NCOT, and 176 (quantifier ion) and 98, 118, 119, 147 qualifier ions for COT. Nicotine-D4 (NCOT-D4) and cotinine-D3 (COT-D3) were used as internal standards with quantifier ions 101 and 166, respectively. The retention time (Rt) for NCOT was 7.557 min and 9.743 min for COT. The method was validated following international principles, assessing characteristics such as absolute recovery, carryover, linearity, specificity, selectivity, accuracy, precision, and stability. The method showed a linear dynamic range from 0.5 to 50 ng/mL, and the limits of detection and quantification were for both NCOT and COT 0.2 and 0.5 ng/mL, respectively. Validation results were found satisfactory.Finally, the method was applied to the analysis of 60 clinical pediatric samples obtained from Aristotle University's pediatric clinic to check for possible exposure to smoke. Concentration levels ranged between 0.5 and 16.2ng/mL for NCOT and between 1.0 and 25.1ng/mL for COT. A rapid, sensitive, accurate, and simple method was developed and used as a tool for the confirmation of passive smoking in children. It is the first method applied to the analysis of such samples belonging to nonsmokers of young age. The total runtime of the GC-MS analysis was short (20 min), and the pretreatment protocol was simple, giving the ability for analysis of a large number of samples on a daily routine basis.

Determination of cotinine and 3-hydroxynicotinine in human serum by liquid chromatography-tandem mass spectrometry and its application

Determination of cotinine and 3-hydroxynicotinine in human serum by liquid chromatography-tandem mass spectrometry and its application

Determination of nicotine and cotinine in human hair using online solid phase extraction coupled with liquid chromatography-tandem mass spectrometry and their relation to hair cortisol and cortisone

Tobacco smoking is one of the critical public health threats all over the world. Since nicotine and its metabolite cotinine have been routinely used as the biomarkers to estimate the exposure to tobacco smoking, hair nicotine and cotinine analyses can provide of a retrospective index of nicotine and cotinine integrated over extended periods of several months prior to hair sampling to estimate the long-term exposure to tobacco smoking. Since the relationship between tobacco smoking and hypothalamic-pituitary-adrenal (HPA) axis is implicated in both stress response and nicotine addiction, better understanding of the association between hair nicotine, cotinine levels and hair cortisol, cortisone levels is an important prerequisite toward more adequate use of this method in future research. We here presented an online solid phase extraction (SPE) coupled with liquid chromatography- tandem mass spectrometry (LC-MS/MS) method for quantification of long-term integrated nicotine and cotinine in human hair. This method was applied to the analysis of hair nicotine and cotinine in 40 participants of smokers and nonsmokers (mean ± SD age: 46.25 ± 11.92 years; 40 % male) and the investigation of their association with hair cortisol and cortisone. Methanol together with glass tube was used for hair nicotine and cotinine extraction during the incubation time of 18-h. The limits of quantification were 1 pg/mg for nicotine as well as 0.1 pg/mg for cotinine. The inter- and intra-day coefficients of variation were below 15 %. The method recovery ranged between 90 % and 104 %. Group-level analyses revealed that smokers exhibited higher hair nicotine and cotinine levels compared to nonsmokers. Hair nicotine and cotinine levels showed significant positive associations with hair cortisol and cortisone levels in smokers (nicotine and cortisol: Spearman's ρ = 0.619, p = 0.005; cotinine and cortisol: Spearman's ρ = 0.468, p = 0.043; nicotine and cortisone: Spearman's ρ = 0.773, p = 0.000; cotinine and cortisone: Spearman's ρ = 0.531, p = 0.016), but not in nonsmokers. The presented online SPE LC-MS/MS method provides a simply and highly specific analytical strategy for the detection of nicotine and cotinine concentrations in human hair for the retrospective assessment of cumulative long-term nicotine and cotinine exposure. Furthermore, hair nicotine, cotinine levels correlate with hair cortisol, cortisone levels in smokers other than nonsmokers.

Investigation of the relationship between nicotine and cotinine concentrations in human biological samples by a GC-MS method

In this study, a gas chromatography-mass spectrometry method was developed for the determination of nicotine and cotinine wherein human plasma, urine, and saliva. In addition, it was aimed to determine statistically the correlation between nicotine and cotinine levels in urine and saliva samples and nicotine and cotinine levels in blood samples. The limit of quantification was ≤0.83 ng/mL and precision were ≤4.91 and accuracy (RE%) was between (-4.93) and 4.90. Recovery was detected between 95.4% and 104.7%. The method was employed to determining the nicotine and cotinine concentrations in plasma, saliva, and urine total of 91 samples belong to non-smokers (n=37) and active smokers (n=54) who were healthy (n=65) and COPD patients (n=27) and the statistical relationship within the nicotine and cotinine values of the samples were investigated. It was found a correlation (r=0.752, p≤0.01) between plasma and saliva cotinine levels and estimation equation calculated as y=1.56x+43.24. Also, the correlation between plasma and urine cotinine levels was found (r=0.787, p≤0.01) by the equation that y=0.31x+34.59. The results show that by accurately determining the amount of cotinine in both saliva and urine, the exposure risks of both active smokers and those exposed to cigarette smoke with the ETS can be estimated.

Influence of Selective Extraction/Isolation of Heme/Hemoglobin with Hydrophobic Imidazolium Ionic Liquids on the Precision and Accuracy of Cotinine ELISA Test.

In this study, ionic liquids were used for the selective extraction/isolation of hemoglobin from human serum for cotinine determination using the ELISA Kit. The suitability of hydrophobic imidazolium-based ionic liquids was tested, of which OMIM BF4 (1-methyl-3-octylimidazolium tetrafluoroborate) turned out to be the most suitable for direct extraction of hemoglobin into an ionic liquid without the use of any additional reagent at one extraction step. Hemoglobin was separated quantitatively (95% recovery) from the remaining types of proteins remaining in the aqueous phase. Quantum mechanical calculations showed that the interaction of the iron atom in the heme group and the nitrogen atom of the ionic liquid cation is responsible for the transfer of hemoglobin whereas molecular dynamics simulations demonstrated that the non-covalent interactions between heme and solvent are more favorable in the case of OMIM BF4 in comparison to water. The opposite trend was found for cotinine. Selective isolation of the heme/hemoglobin improved the ELISA test's accuracy, depending on the cotinine level, from 15% to 30%.

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 a 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. The 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 (ISs). Other non-deuterated ISs such as ritonavir, N-ethylnorcotinine, and milrinone were also used. For both nicotine and cotinine, the calibration range was 0.005-35,000 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 1-10days, at -80°C for up to 6months, and after three to six freeze-thaw cycles. Comedications did not affect nicotine and cotinine analyses.

Paper-Based Competitive Immunochromatography Coupled with an Enzyme-Modified Electrode to Enable the Wireless Monitoring and Electrochemical Sensing of Cotinine in Urine

This paper proposes a combined strategy of using paper-based competitive immunochromatography and a near field communication (NFC) tag for wireless cotinine determination. The glucose oxidase labeled cotinine antibody specifically binds free cotinine in a sample, whereas the unoccupied antibody attached to BSA-cotinine at the test line on a lateral flow strip. The glucose oxidase on the strip and an assistant pad in the presence of glucose generated H2O2 and imposed the Ag oxidation on the modified electrode. This enabled monitoring of immunoreaction by either electrochemical measurement or wireless detection. Wireless sensing was realized for cotinine in the range of 100–1000 ng/mL (R2 = 0.96) in PBS medium. Undiluted urine samples from non-smokers exhibited an Ag-oxidation rate three times higher than the smoker’s urine samples. For 1:8 diluted urine samples (smokers), the proposed paper-based competitive immunochromatography coupled with an enzyme-modified electrode differentiated positive and negative samples and exhibited cotinine discrimination at levels higher than 12 ng/mL. This novel sensing platform can potentially be combined with a smartphone as a reader unit.

Third-hand exposure at homes: Assessment using salivary cotinine

Background/ObjectivesWhile exposure to secondhand smoke (SHS) is a well-established problem, exposure to third-hand smoke (THS) is scanty known and needs to be studied. The objective of this work is to characterize salivary cotinine concentrations among people who self-reported exposure to SHS and THS at home. MethodsCross-sectional study of a representative sample (n = 736) of the adult population (≥16 years) from the city of Barcelona carried out in 2013–2014. A questionnaire on tobacco use and passive exposure was administered, and a saliva sample was collected for cotinine determination. For this study, the information of the non-smoker participants who provided saliva sample (n = 519) was used. The geometric means (GM) and geometric standard deviations (GSD) of the cotinine concentration were compared according to the type of self-reported exposure at home: (1) Not exposed to SHS or THS; (2) Exposed to SHS and THS; and (3) Only exposed to THS. We used log-linear models to compare the cotinine concentration of each exposed group with respect to the unexposed group, adjusting for sex, age, educational level, and tobacco exposure in other settings. ResultsThe GM of the salivary cotinine concentration was 0.34 ng/ml (GSD = 0.16) among individuals reporting SHS and THS exposure, 0.22 ng/ml (GSD = 0.15) among those reporting only THS exposure and 0.11 ng/ml (GSD = 0.04) among those who declared not to be exposed to SHS nor THS (p-value for trend <0.001). The regression model showed a statistically significant increase in cotinine concentration among those exposed to SHS and THS (188% higher, 95% CI: 153%; 223%), and only exposed to THS (106% higher, IC95. %: 74.5%; 137.0%) when comparing with the unexposed group. No statistically significant differences in cotinine concentration were observed between those exposed to SHS and THS compared to the THS group (−25.8%, 95% CI: −69.5%; 17.9%). Conclusions/RecommendationsPeople exposed to third-hand smoke at home had quantifiable cotinine levels in saliva. No differences in cotinine levels were found between those exposed to second-hand and third-hand smoke at home. The reduction of exposure to third-hand smoke at home should be put into the agenda of tobacco control.

Determination of cotinine in human urine by high-performance liquid chromatography

A reversed-phase liquid chromatography with ultraviolet detection is described for the determination of cotinine. A mobile phase consisted of an acetate buffer with sodium octanesulfonate as an ion pair reagent and methanol was used to resolve cotinine from theobromine, theophylline, arecoline and nicotine. Using an octadecyl-type column, a good separation was achieved in 12 min. The wavelength of UV detector was set at 260 nm. With p-nitroaniline as internal standard, human urine samples were cleaned up by liquid-liquid extraction. The regression equations obtained from both the standard and the biological samples were linear between 0.1 - 10.0 μg/mL (r > 0.999). The detection limit for cotinine is 30.0 ng/mL. The R.S.D. and R.E. of intraday and interday are less than 3.93% and 3.07%, respectively (n = 6). The recoveries are all greater than 96.44%. This method has been successfully applied to the determination of urinary cotinine content in several heavy smokers.

High throughput bar adsorptive microextraction: A simple and effective analytical approach for the determination of nicotine and cotinine in urine samples

A simple, effective, convenient and environmentally friendly methodology using high throughput bar adsorptive microextraction (HT-BAμE) with microliquid desorption in combination with large volume injection-gas chromatography-mass spectrometry operating in the selected-ion monitoring acquisition mode (LVI–GC–MS(SIM)) was applied for the determination of nicotine and cotinine in urine samples. Under optimized experimental conditions, the developed methodology allowed for linear dynamic ranges between 20.0 and 2000.0 μg L-1 with determination coefficients of 0.9991 and 0.9992, as well as average recovery yields of 61.7–67.5% and 53.9–57.8% for nicotine and cotine, respectively. The developed methodology was applied to monitor urine samples from 86 volunteers having different smoking habits, where nicotine and cotinine were quantified in the range from 23.6 to 2612.6 μg L-1.The target compounds were extracted in a HT-BAμE apparatus, which allows for simultaneous microextraction and subsequent back-extraction of up to 100 samples. This is a major improvement over other microextraction techniques.The data from the proposed methodology were satisfactory and in line with current green analytical chemistry guidelines, and proved to be an effective sample preparation alternative with substantial potential for high throughput bioanalysis.

Self-Reported Smoking Compared to Serum Cotinine in Bariatric Surgery Patients: Smoking Is Underreported Before the Operation

BackgroundSmoking has been associated with postoperative complications and mortality in bariatric surgery. The evidence for smoking is based on self-report and medical charts, which can lead to misclassification and miscalculation of the associations. Determination of cotinine can objectively define nicotine exposure. We determined the accuracy of self-reported smoking compared to cotinine measurement in three phases of the bariatric surgery trajectory.MethodsPatients in the phase of screening (screening), on the day of surgery (surgery), and more than 18 months after surgery (follow-up) were consecutively selected. Self-reported smoking was registered and serum cotinine was measured. We evaluated the accuracy of self-reported smoking compared to cotinine, and the level of agreement between self-report and cotinine for each phase.ResultsIn total, 715 patients were included. In the screening, surgery, and follow-up group, 25.6%, 18.0%, and 15.5%, respectively, was smoking based on cotinine. The sensitivity of self-reported smoking was 72.5%, 31.0%, and 93.5% in the screening, surgery, and follow-up group, respectively (p < 0.001). The specificity of self-report was > 95% in all groups (p < 0.02). The level of agreement between self-report and cotinine was 0.778, 0.414, and 0.855 for the screening, surgery, and follow-up group, respectively.ConclusionsUnderreporting of smoking occurs before bariatric surgery, mainly on the day of surgery. Future studies on effects of smoking and smoking cessation in bariatric surgery should include methods taking into account the issue of underreporting.

Simultaneous determination of plasma nicotine and cotinine by UHPLC-MS/MS in C57BL/6 mice and its application in a pharmacokinetic study.

Plasma concentrations of nicotine and its active metabolite cotinine are highly correlated with its biological effects. A UHPLC-MS/MS method was developed, validated and applied for nicotine and cotinine analysis in mice plasma. Chromatographic separation was achieved on a BEH HILIC column using acetonitrile (0.1% formic acid) and 10 mm ammonium formate as mobile phase. The gradient elution was performed at 0.4 mL/min with a run time of 3.6 min. The quantitative ion transition was m/z 163.1 > 130.0 for nicotine, m/z 177.1 > 80.0 for cotinine and m/z 167.1 > 134.0 for nicotine-D4 (internal standard, IS). For both nicotine and cotinine, the calibration range was 5-500 ng/mL with 5 ng/mL as the lower limit of quantitation, and the intra- and inter-day bias and imprecision were -4.61-12.00% and <11.12%. The IS normalized recovery was 90.62-98.95% for nicotine and 89.18-101.53% for cotinine, and the IS normalized matrix factor was 106.00-116.44% for nicotine and 100.34-109.85% for cotinine. Both nicotine and cotinine were stable under conventional storage conditions. The validated method has been applied to a pharmacokinetic study in mice to calculate the pharmacokinetic parameters for both analytes.

A comparison of levels of nicotine and cotinine in hair of tobacco smokers and users of e-cigarettes using GC-MS

The objective of this research project was to develop and validate an analytical method for the determination of nicotine and cotinine in hair samples. Following analysis, a comparison was made in the levels of nicotine and cotinine found in the hair of e-cigarette and tobacco cigarette smokers. The differences in Environmental Tobacco Smoke exposure were also investigated to determine whether e-cigarettes or tobacco cigarettes result in a greater level of nicotine exposure. A total of 23 hair samples were collected from volunteers, and sectioned as both 0–3 cm overview sections, in addition to 3 × 1 cm segmental analysis (subject to sufficient sample). Hair sections were washed, submitted to methanol sonication, alkaline digestion, liquid-liquid extraction, and clean-up using solid-phase extraction [1] . All samples were submitted to GC-MS/MS using a TRACE 1310 GC coupled to TSQ 8000 Evo tandem mass spectrometer from Thermo Fisher Scientific (Waltham, MA, USA) utilising timed-SRM acquisition. Chromatographic separation was achieved using a Thermo Scientific TraceGOLD TG-5MS (20 m × 0.18 mm, 0.18 μm) column. Mean analysis results obtained are presented in Table 1 . When comparing the relative levels of nicotine and cotinine from tobacco smokers and e-cigarette users, the results indicate that tobacco exposure results in nicotine concentrations, approximately 37% higher than those detected in users of e-cigarettes. Hair from e-cigarette users generally contained a higher level of cotinine in all samples, compared to nicotine. A more effective absorption of nicotine may account for a higher level of metabolite (cotinine) detection in the e-cigarette samples. Results indicate there are higher concentrations of the analytes, nicotine and cotinine, in the untreated hair samples when compared to levels detected treated hair samples. The study also investigated the effect of hair colour; grey, white and blonde hair samples contained lower nicotine and cotinine concentrations than brown or black hair in both tobacco and e-cigarette users. A full method validation was performed, providing an analytical method with a measurement of uncertainty at 18% (at cut-off level), linearity was observed for both nicotine and cotinine up to 8 times the top calibrator and within method validation acceptance criteria of R2 > 0.99. The research indicates the usefulness of hair analysis to assess exposure to nicotine and cotinine. The pattern of results indicates a more effective absorption of nicotine from e-cigarette vapour, when compared to nicotine contained within tobacco smoke. The effective bioavailability may vary as a function of solution pH and other ingredients in the vapour liquid [2] .

The effect of maternal tobacco smoking and second-hand tobacco smoke exposure on human milk oxidant-antioxidant status

BackgroundMany women who smoke tobacco continue to do so during lactation, and many non-smoking women are exposed to second-hand tobacco smoke (SHS) during the period that she wishes to breastfeed. There are reports documenting the adverse effects of maternal smoking during lactation on their infant's health; however, the pathophysiological mechanisms underlying these effects are incompletely understood. ObjectivesOur study purpose was to examine the influence of tobacco smoke on biochemical markers reflecting the intensity of oxidative stress using concentration of total protein (TP), trolox equivalent antioxidant capacity (TEAC), S-nitrosothiols (RSNO), nitric oxide (NO), thiobarbituric acid reactive substances (TBARS), reduced glutathione (GSH), glutathione S-transferase (GST), glutathione peroxidase (GPx), superoxide dismutase (SOD), catalase (CAT) in the plasma, colostrum, and mature milk of women who smoke, those only exposed to SHS, and non-smokers. MethodsQuestionnaire data on the tobacco smoking status were verified based on the determination of cotinine by high performance liquid chromatography with diode array detector (HPLC-DAD). Relevant markers of oxidative stress and biochemical parameters were determined using spectrophotometric methods. ResultsWe found that tobacco smoking during lactation increases oxidative stress in the mother's plasma, colostrum, and mature milk, and lesser so in those exposed to SHS. Tobacco smoke significantly increase TBARS and decrease TEAC in colostrum and mature milk. In response to ROS generated by tobacco smoke increase the activity of antioxidant enzymes (SOD, GST, GPx and CAT), p < 0.05. DiscussionSuch exposure to tobacco smoke influences the antioxidant barrier of human colostrum and mature milk that can adversely affect their infant's health. Greater public health awareness of the adverse effects of tobacco smoking during lactation on breast milk quality and its protective effects is urgently needed.

Biomarkers of Exposure to Secondhand and Thirdhand Tobacco Smoke: Recent Advances and Future Perspectives.

Smoking is the leading preventable disease worldwide and passive smoking is estimated to be the cause of about 1.0% of worldwide mortality. The determination of tobacco smoke biomarkers in human biological matrices is key to assess the health effects related to the exposure to environmental tobacco smoke. The biomonitoring of cotinine, the main nicotine metabolite, in human biofluids—including urine, serum or saliva—has been extensively used to assess this exposure. However, the simultaneous determination of cotinine together with other tobacco biomarkers and the selection of alternative biological matrices, such as hair, skin or exhaled breath, would enable a better characterization of the kind and extent of tobacco exposure. This review aims to perform a critical analysis of the up-to-date literature focused on the simultaneous determination of multiple tobacco smoke biomarkers studied in different biological matrices, due to the exposure to secondhand smoke (SHS) and thirdhand smoke (THS). Target biomarkers included both tobacco-specific biomarkers—nicotine and tobacco specific nitrosamine biomarkers—and tobacco-related biomarkers, such as those from polycyclic aromatic hydrocarbons, volatile organic compounds, metals and carbon monoxide. To conclude, we discuss the suitability of determining multiple biomarkers through several relevant examples of SHS and THS exposure.

Determination of Cotinine in Urine and Wastewaters by High Performance Liquid Chromatography Coupled with Tandem Mass-Spectrometric Detection

A technique of extracting cotinine in urine and wastewaters, followed by its quantitative determination, using high performance liquid chromatography combined with tandem mass-spectrometric detection is presented. The method is characterized by low detection limits and high levels of efficiency and sensitivity. The optimal conditions for the solid-phase extraction of cotinine from urine and wastewaters are found. This technique makes it possible to reliably estimate the content of cotinine in the urine of active and passive smokers and in wastewaters.

Application of response surface methodology to vortex-assisted dispersive liquid-liquid extraction for the determination of nicotine and cotinine in urine by gas chromatography-tandem mass spectrometry.

A method of vortex-assisted dispersive liquid-liquid extraction coupled with gas chromatography and tandem mass spectrometry for the determination of nicotine and cotinine in urine was developed. Response surface methodology was applied to obtain the optimum extraction conditions. In this method, Plackett-Burman design was utilized to evaluate the impact of five selected factors on pretreatment procedure. Then, three main factors were optimized using a Box-Behnken design. The optimized method showed good linearities at 1-2000μg/L with correlation coefficients of 0.9998 for nicotine and 0.9986 for cotinine. Recovery was 91.4-106 and 91.7-108% for nicotine and cotinine, respectively. The intraday relative standard derivations of determination were 1.47-4.06% for nicotine and 0.41-3.16% for cotinine, and interday relative standard derivations were 3.03-6.70% for nicotine and 1.64-6.38% for cotinine. The method detection limits for nicotine and cotinine were 0.33 and 0.34μg/L, respectively. A total of 87 urine samples from smokers and nonsmokers were tested with the proposed method. Urinary nicotine and cotinine were 23.0-6.67 × 103 and 18.4-4.17 × 103 μg/(g·cr) for smokers and 1.31-286 and 1.39-131μg/(g·cr) for nonsmokers, respectively. The method is sensitive, suitable and reliable for the determination of nicotine and cotinine in urine and meets the requirements for evaluating short-term tobacco exposure.

Determination of Acetaminophen, Dexchlorpheniramine, Caffeine, Cotinine and Salicylic acid in 100 μL of Whole Blood by UHPLC–MS/MS

A sensitive and robust ultra-high-performance liquid chromatography-tandem mass spectrometry method has been developed and validated for the quantification of acetaminophen, dexchlorpheniramine, caffeine, cotinine and salicylic acid in postmortem blood samples from children younger than 4 years. The sample was prepared by a protein precipitation with ice-cold methanol/acetonitrile mixture (85:15, v/v). The organic phase was evaporated to dryness and the residue was dissolved in the mobile phase. Separation, with gradient elution and an acidic mobile phase, was achieved on an Acquity UPLC® HSS T3 column. The compounds were quantified using a multiple reaction-monitoring mode. Two transitions were monitored for each compound and one for the deuterated internal standards. The mass spectrometric detection in the positive ion mode was performed for all the compounds except salicylic acid which was detected in the negative ionization mode. The limits of quantification were as follows: acetaminophen 0.30 mg/L, dexchlorpheniramine 0.0050 mg/L, caffeine 0.099 mg/L, cotinine 0.00035 mg/L and salicylic acid 1.3 mg/L. Between-assay and within-assay precisions were ≤15% (biases: -10% to 26%) and ≤10%, respectively. Extraction recoveries varied from 93% to 137%. The matrix effects in blood, corrected with deuterated internal standards, were 100% ± 10% for all compounds except dexchlorpheniramine (111%) and caffeine (138%).