Analysis of exhaled breath from smokers,passive smokers and non‐smokers by solid‐phase microextraction gas chromatography/mass spectrometry

In this study, 38 samples of expired air were collected and analyzed from 20 non‐smoking volunteers, four passive smokers and 14 smokers (21 women and 17 men). Measurements were carried out using solid‐phase microextraction (SPME) as an isolation and preconcentration technique. The determination and identification were accomplished by gas chromatography coupled with mass spectrometry (GC/MS). Our data showed that ca 32% of all identified compounds in the breath of healthy non‐smokers were saturated hydrocarbons. In the breath of smoking and passive smoking volunteers hydrocarbons were predominant, but also present were more exogenous analytes such as furan, acetonitrile and benzene than in the breath of non‐smokers. Acetonitrile, furan, 3‐methylfuran, 2,5‐dimethylfuran, 2‐butanone, octane and decane were identified in breath of smoking and passive smoking persons. Copyright © 2008 John Wiley & Sons, Ltd.     

Chromatographic analysis of VOC patterns in exhaled breath from smokers and nonsmokers

Cigarette smoking harms nearly every organ of the body and causes many diseases. The analysis of exhaled breath for exogenous and endogenous volatile organic compounds (VOCs) can provide fundamental information on active smoking and insight into the health damage that smoke is creating. Various exhaled VOCs have been reported as typical of smoking habit and recent tobacco consumption, but to date, no eligible biomarkers have been identified. Aiming to identify such potential biomarkers, in this pilot study we analyzed the chemical patterns of exhaled breath from 26 volunteers divided into groups of nonsmokers and subgroups of smokers sampled at different periods of withdrawal from smoking. Solid‐phase microextraction technique and gas chromatography/mass spectrometry methods were applied. Many breath VOCs were identified and quantified in very low concentrations (ppbv range), but only a few (toluene, pyridine, pyrrole, benzene, 2‐butanone, 2‐pentanone and 1‐methyldecyclamine) were found to be statistically significant variables by Mann–Whitney test. In our analysis, we did not consider the predictive power of individual VOCs, as well as the criterion of uniqueness for biomarkers suggests, but we used the patterns of the only statistically significant compounds. Probit prediction model based on statistical relevant VOCs‐patterns showed that assessment of smoking status is heavily time dependent. In a two‐class classifier model, it is possible to predict with high specificity and sensitivity if a subject is a smoker who respected 1 hour of abstinence from smoking (short‐term exposure to tobacco) or a smoker (labelled "blank smoker") after a night out of smoking (long‐term exposure to tobacco). On the other side, in our study "blank smokers" are more like non‐smokers so that the two classes cannot be well distinguished and the corresponding prediction results showed a good sensitivity but low selectivity.     

Development of an impurity‐profiling method for source identification of spilled benzene series compounds by gas chromatography with mass spectrometry: Toluene as a case study

In this study, an impurity profiling method was established for the source identification of spilled benzene series compounds. Toluene was used as a case study to demonstrate the feasibility of this approach. Gas chromatography with mass spectrometry was applied for identification and quantification of the impurities including ethyl benzene, p‐xylene, m‐xylene, and o‐xylene in toluene. Impurities in toluene were detected at very low levels by applying mass spectrometry in selected‐ion monitoring mode. Eight authentic toluene samples collected from different manufacturers were analyzed by the developed gas chromatography with mass spectrometry method to construct the characteristic impurity profiling of toluene. Then, combined with scatter distribution, similarity analysis and t‐test, a suite of diagnostic ratios based on the impurity distribution was used for the differentiation of toluene from different sources. Results indicated that scatter distribution method can discriminate the original toluene samples from different manufacturers. Similarity calculation and t‐test methods can identify effectively the weathered toluene samples. The proposed impurity profiling method was useful for discrimination between toluene samples from different sources. Statistical analysis of these impurity profiles demonstrated the potential to investigate whether two questioned spilled toluene samples encountered in forensic casework are from the same source.     

Evaluation of serum metal profile in relation to biri smoking using ICP-MS

The metals intake through tobacco smoking is associated with adverse effects for human health. The present study was aimed to understand the effects of biri smoking on smoker’s serum metal profile. Seven metals, cadmium (Cd), nickel (Ni), lead (Pb), chromium (Cr), copper (Cu), iron (Fe) and zinc (Zn), were analysed in serum samples of 20 biri smokers and 20 non-smokers from North India. The Cd, Ni, Pb, Cr and Cu concentrations were higher while Fe and Zn concentrations were lower in smokers compared to non-smokers. The Fe concentrations, the highest among all metals, seemed to be unassociated with the smoking activity. This study indicated that biri smoking is a contributor to the body burden of Cd, Ni, Cu and Cr in the smoker’s body. The Cd, Ni, Cu and Fe concentrations are non-significantly associated with the age of smokers at p < 0.01 significance level, whereas Pb and Cr concentrations increase and Zn concentrations decrease with the increase in the age of smokers. Serum metal concentrations in the smoker subjects of North India are higher compared to the results of other similar studies. This could be linked to the poor quality of tobacco used in biri. We recommend conducting more detailed and controlled studies in this regard as a smoker is also subjected to other sources of exposure to metals.     

Simultaneous analysis of 28 urinary VOC metabolites using ultra high performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (UPLC-ESI/MSMS)

Volatile organic compounds (VOCs) are ubiquitous in the environment, originating from many different natural and anthropogenic sources, including tobacco smoke. Long-term exposure to certain VOCs may increase the risk for cancer, birth defects, and neurocognitive impairment. Therefore, VOC exposure is an area of significant public health concern. Urinary VOC metabolites are useful biomarkers for assessing VOC exposure because of non-invasiveness of sampling and longer physiological half-lives of urinary metabolites compared with VOCs in blood and breath. We developed a method using reversed-phase ultra high performance liquid chromatography (UPLC) coupled with electrospray ionization tandem mass spectrometry (ESI/MSMS) to simultaneously quantify 28 urinary VOC metabolites as biomarkers of exposure. We describe a method that monitors metabolites of acrolein, acrylamide, acrylonitrile, benzene, 1-bromopropane, 1,3-butadiene, carbon-disulfide, crotonaldehyde, cyanide, N,N-dimethylformamide, ethylbenzene, ethylene oxide, propylene oxide, styrene, tetrachloroethylene, toluene, trichloroethylene, vinyl chloride and xylene. The method is accurate (mean accuracy for spiked matrix ranged from 84 to104%), sensitive (limit of detection ranged from 0.5 to 20 ng mL⁻¹) and precise (the relative standard deviations ranged from 2.5 to 11%). We applied this method to urine samples collected from 1203 non-smokers and 347 smokers and demonstrated that smokers have significantly elevated levels of tobacco-related biomarkers compared to non-smokers. We found significant (p < 0.0001) correlations between serum cotinine and most of the tobacco-related biomarkers measured. These findings confirm that this method can effectively quantify urinary VOC metabolites in a population exposed to volatile organics.     

Applications of Hadamard transform-gas chromatography/mass spectrometry to online detection of exhaled breath after drinking or smoking

A Hadamard transform-gas chromatography/mass spectrometry (HT-GC/MS) technique was employed for the online detection of ethanol or toluene in exhaled breath after drinking or smoking, respectively. Exhaled breath samples, collected from volunteers, were directly injected into the GC inlet by a Hadamard-injector without any pretreatment. In the case of breath from a drinker, using a conventional single injection, a small ion peak (corresponding to ∼0.1 ng of ethanol), the intensity of which was approximately equal to or less than the limit of detection. When the HT technique was applied, the signal-to-noise (S/N) ratio was dramatically improved. Furthermore, in the case of breath from a smoker, using conventional injection, a weak ion peak (corresponding to ∼0.7 pg of toluene) was marginally detected. However, the HT technique led to an improvement in the S/N ratio, with the peak corresponding to the limit of detection. In both cases, the HT technique permitted specific components in exhaled breath to be determined, without the need for any extraction procedures.     

Thermochemical Studies for Determination of the Standard Molar Enthalpies of Formation of Alkyl-Substituted Furans and Some Ethers

The standard molar enthalpies of vaporization _l ^g H _m ^º of 2,5-dimethylfuran, 2-tert-butylfuran, 2,5-di-tert-butylfuran, cyclopentenyl methyl ether, cyclohexenyl methyl ether, and tert-amyl methyl ether were obtained from the temperature variation of the vapor pressure measured in a flow system. The standard (p° = 0.1 MPa) molar enthalpies of formation _f H _m ^º (1) at the temperature T = 298.15 K were measured using combustion calorimetry for 2,5-dimethylfuran, 2-tert-butylfuran, and 2,5-di-tert-butylfuran. From the derived standard molar enthalpies of formation for gaseous compounds, ring correction terms and non-nearest neighbor interactions useful in the application of the Benson group additivity scheme were calculated.     

Recognition of benzene, toluene and xylene using TGS array integrated with linear and non-linear classifier

Three volatile organic compounds (VOCs): benzene, toluene and xylene were measured with an array of six Taguchi gas sensors in the air with variable humidity content. The recognition of single compounds was performed, based on measurement results. The principal component analysis (PCA) pointed at humidity as the main classification factor in the measurement data set. The linear discriminant analysis (LDA) was applied to overcome this drawback and enforce classification with respect to benzene, toluene or xylene. It was shown that discriminant function analysis (DFA), which is an LDA method allowed for 100% success rate in test samples recognition of benzene. It did not allow for accurate recognition of test samples of toluene or xylene. Following, the non-linear classifier, radial basis function neural network (RBFNN) was applied. A specific configuration of input ‘s was found, which provided for successful recognition of each single compound: benzene, toluene or xylene in air with variable humidity content.     

Comparison of cannabinoid concentrations in oral fluid and whole blood between occasional and regular cannabis smokers prior to and after smoking a cannabis joint

A cross-over controlled administration study of smoked cannabis was carried out on occasional and heavy smokers. The participants smoked a joint (11 % Δ9-tetrahydrocannabinol (THC)) or a matching placebo on two different occasions. Whole blood (WB) and oral fluid (OF) samples were collected before and up to 3.5 h after smoking the joints. Pharmacokinetic analyses were obtained from these data. Questionnaires assessing the subjective effects were administered to the subjects during each session before and after the smoking time period. THC, 11-hydroxy-THC (11-OH-THC) and 11-nor-9-carboxy-THC (THCCOOH) were analyzed in the blood by gas chromatography or liquid chromatography (LC)-tandem mass spectrometry (MS/MS). The determination of THC, THCCOOH, cannabinol (CBN), and Δ9-tetrahydrocannabinolic acid A (THC-A) was carried out on OF only using LC-MS/MS. In line with the widely accepted assumption that cannabis smoking results in a strong contamination of the oral cavity, we found that THC, and also THC-A, shows a sharp, high concentration peak just after smoking, with a rapid decrease in these levels within 3 h. No obvious differences were found between both groups concerning THC median maximum concentrations measured either in blood or in OF; these levels were equal to 1,338 and 1,041 μg/L in OF and to 82 and 94 μg/L in WB for occasional and heavy smokers, respectively. The initial WB THCCOOH concentration was much higher in regular smokers than in occasional users. Compared with the occasional smokers, the sensation of confusion felt by the regular smokers was much less while the feeling of intoxication remained almost unchanged.

In situ analysis of solvents on breath and blood: a selected ion flow tube mass spectrometric study

We report measurements of residual vapour levels of xylenes and trimethylbenzenes, present following a floor re-surfacing procedure, using the technique of selected ion flow tube mass spectrometry (SIFT-MS). A subject exposed to controlled amounts of xylene and mesitylene was monitored by direct breath exhalation over a 4-hour period after exposure to the volatile organic compounds (VOCs) had stopped. The headspace gases above 5 mL blood samples taken over this period were also monitored. The decays of the solvent levels with time were fitted to a two-compartment model with residence times for xylene and mesitylene of 0.37 h and 0.38 h, respectively (compartment one) and 2.5 h and 2.8 h, respectively (compartment two).     

Determination of urinary t-t muconic acid as biomarker of environmental benzene intake and its interference factors

The target of our study was the determination of urinary t,t muconic acid concentration, as a biomarker of benzene intake in a population. Urinary samples of 101 subjects, males and females were obtained to whom. Information regarding modification and confounding factors were recorded by questionnaire. The samples were analysed by HPLC, after extraction of trans,trans muconic acid on strong anionic exchange cartridges. In these analytical conditions the detection limit with good care is 10 micrograms/l. A concentration range from 10 to 1300 micrograms/l was found. High levels found in the population could explained by confounding factors present. The obtained results were correlated with sex, age and smoking or non smoking. There was a significant difference in mean concentrations between heavy smokers (160 micrograms/l) and non smokers (110 micrograms/l), that showed tobacco as an interference factor. The study showed that it is strictly necessary carry out a thorough anamnesis before sampling with the objective of finding eventual interference factors such as smoking, diet and drugs taken.     

Quantitative analysis of trace‐level benzene,toluene, ethylbenzene,and xylene in cellulose acetate tow using headspace heart‐cutting multidimensional gas chromatography with mass spectrometry

This study describes a method for the quantification of trace‐level benzene, toluene, ethylbenzene, and xylene in cellulose acetate tow by heart‐cutting multidimensional gas chromatography with mass spectrometry in selected ion monitoring mode. As the major volatile component in cellulose acetate tow samples, acetone would be overloaded when attempting to perform a high‐resolution separation to analyze trace benzene, toluene, ethylbenzene, and xylene. With heart‐cutting technology, a larger volume injection was achieved and acetone was easily cut off by employing a capillary column with inner diameter of 0.32 mm in the primary gas chromatography. Only benzene, toluene, ethylbenzene, and xylene were directed to the secondary column to result in an effective separation. The matrix interference was minimized and the peak shapes were greatly improved. Finally, quantitative analysis of benzene, toluene, ethylbenzene, and xylene was performed using an isotopically labeled internal standard. The headspace multidimensional gas chromatography mass spectrometry system was proved to be a powerful tool for analyzing trace volatile organic compounds in complex samples.     

聚氧乙烯-聚氧丙烯嵌段共聚物加溶作用的研究

本文对聚氧乙烯-聚氧丙烯嵌段共聚物Pluronic的加溶性质和机制进行了研究. 结果表明仅有合适的HLB值的样品才具有加溶作用. L64的水溶液对芳烃有加溶作用, 对烷烃几乎没有. 随温度升高,发生加溶作用的L64最小浓度下降. 此外, 水也能被加溶在L64的二甲苯溶液中. 加溶有水的反胶团的大小比加溶有二甲苯的正胶团要大得多. 紫外光谱与核磁共振谱的研究表明, 对于PPO-PEO嵌段共聚物, 被加溶的二甲苯插在胶团内部的PPO链段之间。     

Chemiluminescence detection of five-membered heteroaromatic compounds using electrogenerated tris(2,2'-bipyridine)-ruthenium(III).

Heteroaromatic compounds, such as 2,5-dimethylthiophene, 2,5-dimethylpyrrole, and 2,5-dimethylfuran, were found to act as reducing agents for the tris(2,2'-bipyridine)ruthenium(III), Ru(bpy)3(3+), chemiluminescent reaction. In order to characterize the chemiluminescent reaction of Ru(bpy)3(3+) with heteroaromatic compounds, we have investigated various mono-, di-, and tri-heteroaromatic compounds. The pi-electron density and stability of aromatic rings influence the chemiluminescent efficiency of the reaction. Above all, 2,5-dimethylthiophene produced strong chemiluminescence under acidic conditions. In addition, we confirmed that the rate of the chemiluminescent reaction of Ru(bpy)3(3+) with 2,5-dimethylthiophene is very fast.     

Lewis acid-catalyzed reactions of donor-acceptor cyclopropanes with furan derivatives

Lewis acid-catalyzed reactions of dialkyl 2-arylcyclopropane-1,1-dicarboxylates with 2,5-dimethylfuran were found to give products of [3+2]-cycloaddition to C(2)-C(3) bond, which contain reactive vinyl ether moiety. These adducts can be further transformed into various products depending on the Lewis acid, the nucleophilicity of aryl group in starting cyclopropane and the ratio of reagents. The vinyl ether moiety can attack the appropriate nucleophilic center in intramolecular or intermolecular mode or can undergo cycloaddition to the second equivalent of donor-acceptor cyclopropane. Alternatively, 2,5-diphenylfuran formed Friedel-Crafts products only when reacted with donor-acceptor cyclopropanes.     

Detection of cysteine- and lysine-based protein adductions by reactive metabolites of 2,5-dimethylfuran

Many furan-containing compounds are known to be toxic and/or carcinogenic. Metabolic activation of toxic furans to cis-enediones (cis-enedials or γ-ketoenals) is generally considered as the initial step towards the processes of their toxicities. Sequential modification of key proteins by the electrophilic reactive intermediates is suggested to be an important mechanism of the toxic actions. In the present study, we developed a novel and simple analytical platform to detect protein modification resulting from metabolic activation of model compound 2,5-dimethylfuran (DMF). 4-Bromobenzylamine and 4-bromobenzylmercaptan were employed to trap protein adductions at cysteine and lysine residues, respectively. The resulting protein samples were proteolytically digested by chymotrypsin and Pronase E, followed by LC–MS/MS analysis. Modifications of cysteine and lysine residues of proteins were observed in microsomal incubations and animals after exposure to DMF. In conclusion, the approach established has been proven highly selective and reliable. This advance allows us not only to detect the protein adductions but also to define the structural identities of amino acid residues modified. This technique provides a unique platform to assess protein modifications arising from metabolic activation of potentially harmful furan-containing compounds. Hepatic protein adductions were found to be proportional to the hepatotoxicity of DMF.     

Turn‐On Fluorogenic and Chromogenic Detection of Small Aromatic Hydrocarbon Vapors by a Porous Supramolecular Host

Benzene, toluene, ethylbenzene, the isomers of xylene, and trimethylbenzene are harmful volatile organic compounds and pose risks to human health and the environment. However, there are currently no effective chemosensors for vapors of these compounds. A porous supramolecular host for turn‐on fluorogenic and chromogenic detection of the vapors of small aromatic hydrocarbons is presented. The host was constructed from a naphthalenediimide derivative that was supramolecularly connected to tris(pentafluorophenyl)borane. The amorphous powder form of the host allowed for effective accommodation of vapors of small aromatic hydrocarbons, resulting in a guest‐dependent fluorescence emission. Increases in the fluorescence yield of 76‐, 46‐, and 37‐fold were observed with toluene, benzene, and m‐xylene, respectively. Negligible responses were obtained with common organic solvents. This simple supramolecular host could be applied as a useful sensor of small aromatic hydrocarbon vapors.     

A New Protocol to Generate Catalytically Active Species of Group 4–6 Metals by Organosilicon-Based Salt-Free Reductants

Herein, we provide a new protocol to reduce various transition-metal complexes by using organosilicon compounds in a salt-free fashion with the great advantage of generating pure low-valent metal species and metallic(0) nanoparticles, in sharp contrast to reductant-derived salt contaminants obtained by reduction with metal reductants. The organosilicon derivatives 1,4-bis(trimethylsilyl)-2,5-cyclohexadiene ( 1 a ), 1-methyl-3,6-bis(trimethylsilyl)-1,4-cyclohexadiene ( 1 b ), 1,4-bis(trimethylsilyl)-1,4-diaza-2,5-cyclohexadiene ( 2 a ), 2,5-dimethyl-1,4-bis(trimethylsilyl)-1,4-diaza-2,5-cyclohexadiene ( 2 b ), 2,3,5,6-tetramethyl-1,4-bis(trimethylsilyl)-1,4-diaza-2,5-cyclohexadiene ( 2 c ), and 1,1′-bis(trimethylsilyl)-1H,1′H-4,4′-bipyridinylidene ( 3 ) all served as versatile reductants for early transition-metal complexes and produced only easy-to-remove organic compounds, such as trimethylsilylated compounds and the corresponding aromatics, for example, benzene, toluene, pyrazine, and 4,4′-bipyridyl, as the byproducts. The high solubility of the reductants in organic solvents enabled us to monitor the catalytic reactions directly and to detect any catalytically active species so that we could elucidate the reaction mechanism.     

Development and optimization of an HPLC–DAD method for quantification of six petroleum hydrocarbon compounds in aqueous samples

Benzene, toluene, and xylene isomers (BTXs) and pyrene, benzo(b)fluoranthene, and benzo(a)pyrene (polycyclic aromatic hydrocarbons) are common pollutants found in many industrial effluents and in aquifers due to fossil fuels spill from underground storage reservoirs. For these reasons, the determination of these compounds has gained importance in the last decades. In this work, a simultaneous, fast, and accurate quantification of six petroleum hydrocarbon compounds (such as BTXs, pyrene, benzo(b)fluoranthene, and benzo(a)pyrene) using a high-performance liquid chromatography–diode array detector method has been demonstrated. The proposed method is suitable for the direct aqueous sample evaluation and also brings advantages, including the use of small volumes of organic solvents, with high resolution, reducing the analysis cost. The method was also checked using synthetic and real samples, including those containing surfactants, commercial gasoline, and river water samples spiked with petroleum hydrocarbon compounds.     

The Influence of Smoking Status on Exhaled Breath Profiles in Asthma and COPD Patients

Breath analysis using eNose technology can be used to discriminate between asthma and COPD patients, but it remains unclear whether results are influenced by smoking status. We aim to study whether eNose can discriminate between ever- vs. never-smokers and smoking <24 vs. >24 h before the exhaled breath, and if smoking can be considered a confounder that influences eNose results. We performed a cross-sectional analysis in adults with asthma or chronic obstructive pulmonary disease (COPD), and healthy controls. Ever-smokers were defined as patients with current or past smoking habits. eNose measurements were performed by using the SpiroNose. The principal component (PC) described the eNose signals, and linear discriminant analysis determined if PCs classified ever-smokers vs. never-smokers and smoking <24 vs. >24 h. The area under the receiver–operator characteristic curve (AUC) assessed the accuracy of the models. We selected 593 ever-smokers (167 smoked <24 h before measurement) and 303 never-smokers and measured the exhaled breath profiles of discriminated ever- and never-smokers (AUC: 0.74; 95% CI: 0.66–0.81), and no cigarette consumption <24h (AUC 0.54, 95% CI: 0.43–0.65). In healthy controls, the eNose did not discriminate between ever or never-smokers (AUC 0.54; 95% CI: 0.49–0.60) and recent cigarette consumption (AUC 0.60; 95% CI: 0.50–0.69). The eNose could distinguish between ever and never-smokers in asthma and COPD patients, but not recent smokers. Recent smoking is not a confounding factor of eNose breath profiles.