Gas Chromatography-tandem Mass Research Articles

Better Together: Tandem Mass Spectrometry Achieves up to 50 Times Lower Quantification of 62 Disinfection Byproducts in Drinking Water.

Disinfection byproducts (DBPs) are ubiquitous contaminants present in nearly all drinking water and are associated with adverse health effects in human epidemiologic studies. The most toxic DBPs are unregulated and often occur at concentrations well below regulated DBPs; thus, quantification at low parts-per-trillion (ng/L) levels is critical in assessing exposure. We developed a new liquid-liquid extraction-gas chromatography-tandem mass spectrometry (LLE-GC-MS/MS) method with the first analysis by tandem gas chromatography-mass spectrometry of 23 priority unregulated DBPs including 13 haloacetamides, 3 haloacetic acids, 2 haloacetonitriles, 1 haloacetaldehyde, 2 haloketones, and 2 halonitromethanes. When combined with our previous GC-MS/MS method for haloacetic acids and previously reported MS/MS transitions that we optimized for this method, the analysis of 62 regulated and priority unregulated DBPs at lower quantification limits is achieved. Limits of quantification for most DBPs were between 5 and 30 ng/L with r2 > 0.99 and an average of 9 times lower limits of quantification (LOQs) compared to LLE-GC-MS using selected ion monitoring (SIM). Relative standard deviations ranged from 0.7 to 30% for 61 DBPs in spiked samples. This new method was validated using tap waters from four US cities, where individual DBP concentrations ranged from 5 to 126,882 ng/L. This project provides the most comprehensive GC-MS/MS method for DBP analysis to date and is capable of analyzing volatile and semivolatile DBPs across nine different compound classes, including a class not previously analyzed by GC-MS/MS.

Accumulation of organophosphorus pollutants in adipose tissue of obese women - metabolic alterations

Organophosphorus pesticides (OPPs) and organophosphate esters (OPEs) are organophosphorus compounds created as substitutes for persistent environmental pollutants, namely organochlorines pesticides and brominated flame retardants, respectively. However, there is evidence that organophosphorus compounds are also widespread across the environment and have adverse effects on biota. In humans, OPPs and OPEs were reported to be carcinogenic, neurotoxic, hepatotoxic, nephrotoxic, amongst others. As lipophilic compounds, these accumulate in fat tissues as adipose tissue. Yet biomonitoring studies and analytical methodologies to assess these compounds in the human body are scarce, particularly in adipose tissue. In this study, the presence of six OPPs and seven OPEs was determined in samples of subcutaneous adipose tissue (scAT) and visceral adipose tissue (vAT) from 188 adult obese women. OPPs and OPEs were quantified by gas chromatography (GC) flame photometric detection and confirmed in GC tandem mass spectrometry. The detection frequencies ranged between 0.5-1.6% and 48–53%, respectively for OPPs and OPEs. Organophosphorus pollutants were present in both adipose tissues and median concentrations were 0.008 ± 0.020 μg/g scAT and 0.009 ± 0.020 μg/g vAT. A total of 32 Spearman's correlations were found between organophosphorus pollutants concentrations in adipose tissue and several biochemical parameters (18 positive and 14 negative). Our results show that anthropometric and hormonal parameters, cholesterol, glycaemia, macrominerals, urea and sedimentation velocity might be influenced by the presence of these compounds. The presence of organophosphorus pollutants in the environmental and their possible effect on female metabolic processes is concerning. Particularly because presently OPEs usage is not controlled or limited by any regulation. More studies are needed to fully understand these pollutants behaviour and hazard effects on human health, biota, and the environment so control regulations can be drawn to prevent and lessen their effects.

Urinary phthalate metabolites and heart rate variability: A panel study

Phthalates exposure is linked with cardiovascular disease. Decreased heart rate variability (HRV) is an early indicator of cardiac autonomic imbalance. We conducted a longitudinal panel study in 127 Chinese adults with 3 repeated visits to explore the associations of individual and mixtures of phthalates exposure with HRV. We quantified 10 urinary phthalate metabolites by gas chromatograph-tandem mass spectrometer (GC-MS/MS) and 6 HRV indices by 3-channel digital Holter monitors. Linear mixed-effect (LME) models and Bayesian kernel machine regression (BKMR) models were separately implemented to evaluate the associations. After multivariate adjustments, we found that urinary mono-ethyl phthalate (MEP), mono-iso-butyl phthalate (MiBP), and mono-n-butyl phthalate (MBP) at lag 0 day were inversely associated with low-frequency power (LF) or total power (TP) (all P-FDR <0.05). In mixture analysis, we observed negative overall associations of phthalate mixtures at lag 0 day with LF or TP, and MiBP was the major contributor. Moreover, stratified analysis suggested that the inverse relationships of MiBP at lag 0 day with LF and TP were more prominent in subjects aged >50 years (all Pinteraction < 0.01). Our findings revealed that exposure to individual and mixtures of phthalates, especially MiBP, were related to decreased HRV.

Machine Learning-Assisted Identification and Quantification of Hydroxylated Metabolites of Polychlorinated Biphenyls in Animal Samples.

Laboratory studies of the disposition and toxicity of hydroxylated polychlorinated biphenyl (OH-PCB) metabolites are challenging because authentic analytical standards for most unknown OH-PCBs are not available. To assist with the characterization of these OH-PCBs (as methylated derivatives), we developed machine learning-based models with multiple linear regression (MLR) or random forest regression (RFR) to predict the relative retention times (RRT) and MS/MS responses of methoxylated (MeO-)PCBs on a gas chromatograph-tandem mass spectrometry system. The final MLR model estimated the retention times of MeO-PCBs with a mean absolute error of 0.55 min (n = 121). The similarity coefficients cos θ between the predicted (by RFR model) and experimental MS/MS data of MeO-PCBs were >0.95 for 92% of observations (n = 96). The levels of MeO-PCBs quantified with the predicted MS/MS response factors approximated the experimental values within a 2-fold difference for 85% of observations and 3-fold differences for all observations (n = 89). Subsequently, these model predictions were used to assist with the identification of OH-PCB 95 or OH-PCB 28 metabolites in mouse feces or liver by suggesting candidate ranking information for identifying the metabolite isomers. Thus, predicted retention and MS/MS response data can assist in identifying unknown OH-PCBs.

Evaluation and optimization of a HS-SPME-assisted GC-MS/MS method for monitoring nitrosamine impurities in diverse pharmaceuticals

The probable carcinogenic nitrosamine impurities, such as N-nitrosodiethylamine (NDEA) and N-nitrosodimethylamine (NDMA), have been detected from various pharmaceuticals in recent years. The sensitive chromatographic methods, including liquid chromatography (LC) and gas chromatography (GC), have been applied for analyzing nitrosamines in the pharmaceutical substrates, such as sartans, ranitidine and metformin. In comparison of LC, the efficacy of GC for analyzing multiple nitrosamines in diverse pharmaceuticals will be limited or attenuated owing to the chemical properties of target analytes or matrix hinderance of pharmaceutical substrates. To extend the applicability of GC analysis for multiple nitrosamines in pharmaceuticals, this study presented a gas chromatograph tandem mass (GC-MS/MS) method for monitoring 14 nitrosamines within 44 pharmaceuticals, whereas the headspace-solid phase microextraction (HS-SPME) sampling mode was introduced. Chromatographic separation was achieved on a DB-heavyWax column (30 m × 0.25 mm; i.d., 0.25 µm), whereas the HS-SPME sampling mode with a 50/30 µm DVB/CAR/PDMS extracting fiber was applied for comparison of the direct injection mode. Meanwhile, the HS-SPME conditions were optimized to evaluate the effects of the parameters on analyzing total nitrosamines in pharmaceuticals by GC-MS/MS. The optimal conditions of HS-SPME were as follows: extracting solution of 90% NaCl, HS incubation time 1 min, SPME adsorbing at 80 ℃ for 30 min, and desorbing at 250 ℃ for 5 min. The limit of quantification (LOQ) for 14 nitrosamines in pharmaceutical matrices under the optimal conditions was 0.05 μg/g for the optimal HS-SPME, whereas the value was 0.05˗0.25 μg/g for direct injection.

An unusual case of fatal hypothermia involving topical diphenhydramine.

Diphenhydramine is an antihistamine drug widely used to alleviate symptoms caused by allergies and the common cold. Diphenhydramine-involved fatalities have been reported in the past but usually involving overdose by ingestion. We report a peculiar case of fatal hypothermia during non-winter season involving topical diphenhydramine. A 23-year-old male with no known preexisting medical conditions was found dead in the bathroom of his apartment with a small amount of running water on his back. Postmortem examinations and toxicological analysis on blood and urine were performed. Color difference was apparent between the right and left cardiac blood. Wischnewski spots were observed in the gastric mucosa. Histological examination revealed no obvious findings that could attribute to serious cardiovascular events. Drug screening by gas chromatograph-tandem mass spectrometry (GC/MS/MS) detected diphenhydramine in blood and urine. Further quantification revealed the postmortem concentrations to be 0.44μg/mL in blood and 2500μg/mL in urine. The cause of death was determined to be hypothermia. Diphenhydramine-induced drowsiness and possible intrinsic cardiac factor may have led to prolonged impaired consciousness, preventing his ability to escape from the running cold water leading to hypothermia and death.

Serum polychlorinated biphenyls levels in some reproductive aged men in Wuhan and the influencing factors in 2013

To measure polychlorinated biphenyls(PCBs) concentrations in serum of some reproductive aged men in Wuhan and explore the influencing factors of PCBs exposure. Based on a cross-sectional study in 2013 on the association between exposure to environmental pollutants and adverse male reproductive health, which was conducted in Wuhan. Levels of dioxins-like PCBs(dl-PCBs) and non-dioxin-like PCBs(ndl-PCBs) in 101 serum samples of men with childbearing age were analyzed via high-resolution gas chromatograph tandem high-resolution mass spectrometer(HRGC-HRMS) method. Multiple linear regression models were used to analyze the associations between PCBs levels and influencing factors. Total concentrations of twelve dl-PCBs(Σdl-PCBs) were in range of 177.85-7271.48 pg/g lipid, the median value was 1530.71 pg/g lipid, and CB-118 was the predominant congener. For six ndl-PCBs, total concentrations(Σndl-PCBs) were in range of 1463.23-40561.47 pg/g lipid, the median value was 5498.37 pg/g lipid, and CB-153 was the predominant congener. The World Health Organization toxicity equivalent(WHO_(2005)-TEQ) of dl-PCBs(ΣTEQ_(dl-PCBs)) were 0.02-162.29 pg TEQ/g lipid, the median value was 1.77 pg TEQ/g lipid. The age was positively correlated with Σmono-ortho PCBs(β=0.01, 95%CI 0.00-0.02), ΣTEQ_(mono-ortho PCBs)(β=0.01, 95%CI 0.00-0.02) and Σndl-PCBs(β=0.02, 95%CI 0.00-0.03). Men who drank alcohol tend to show higher exposure to ΣTEQ_(dl-PCBs)(β=0.56, 95%CI 0.13-1.00) than those did not drink alcohol. And higher levels of Σndl-PCBs(β=0.15, 95%CI 0.04-0.26) was found in the men who reside in urban areas as compared to rural one. There were PCBs exposure in some reproductive aged men in Wuhan. Age, drink alcohol status, and residence were influencing factors on PCBs.

Enantiomeric profiling of amphetamines in wastewater using chiral derivatisation with gas chromatographic-tandem mass spectrometric detection

Enantiomeric profiling can supplement wastewater-based epidemiology (WBE) by providing additional information on drug origin (licit or illicit), improving consumption estimates, i.e., differentiating between disposal and consumption, and offering an insight into the potency of drugs available on the illicit drug market. We report on the enantiomeric profiling of amphetamines in wastewater using R(-)-α-methoxy-α-(trifluoromethyl) phenylacetyl chloride (R-MTPCl), a chiral derivatising agent and GC–MS/MS. The method performed well when evaluated against the SANTE/12682/2019 guidelines in terms of recovery (81–99%), accuracy (99–111%), repeatability (1–8%RSD) and linearity (LOQ–1000 ng/mL). The LOD and LOQ were 120 ng/L and 400 ng/L, respectively. The method was applied to samples of raw wastewater from two Slovene municipalities with unusual levels of amphetamines: Ljubljana (LJ1) and Velenje (VE1). LJ1 had an anomalously high mass load of MDMA (3,4-methylenedioxymethamphetamine) identified during SCORE 2020, and VE1 is a representative sample of the consistently high mass load of amphetamine. A second Ljubljana sample (LJ2) was chosen as a representative sample. The presence of racemic MDMA (EF = 0.511) in LJ1 indicated the disposal of the unused drug into the sewer, while the enrichment of R-MDMA (EF = 0.666) in the combined extract sample from Ljubljana (LJ2) indicated consumption. In the case of Velenje and Ljubljana, it is impossible to distinguish between the direct disposal and consumption of amphetamine and methamphetamine. Also, since amphetamine/methamphetamine-based prescription medications are unavailable in Slovenia, racemic amphetamine in VE1 (EF = 0.514) and LJ2 (EF = 0.459) indicate racemic and the more potent S-amphetamine are sold on the illicit drug market. Only S-methamphetamine was detected in wastewater (LJ2: EF = 0), indicating the presence of only the more potent S-methamphetamine on the illicit drug market. Overall, enantiomeric profiling provided useful information on amphetamine residues. In addition, chiral derivatisation can be a cost-effective alternative to using chiral chromatographic columns for the enantiomeric profiling of amphetamines in wastewater.

Changes in methotrexate polyglutamate concentration in patients with rheumatoid arthritis during treatment and after discontinuation (review of two cases)

Introduction. The dynamics of changes in the concentration of polyglutamates of methotrexate (MTPG) over the past 20 years has been studied by several scientifc groups using various methods. For a number of reasons, the results of these studies cannot be called uniform and cannot be confdently projected onto the Russian population of patients with rheumatoid arthritis (RA). At the same time, therapeutic drug monitoring of methotrexate (MT) with clearly defned target values of metabolites could be an extremely useful tool in routine clinical practice.Purpose of the study. To characterize the concentration of MTPG in dynamics during treatment and 12 weeks after discontinuation of MT.Materials and methods. Two patients with early RA were traced 4, 12, 24 weeks after MT appointment, and also 12 weeks after its cancellation due to nausea that appeared during treatment. At each visit, an analysis was made for MTPG content by tandem gas chromatography-mass spectrometry.Results. Against the background of treatment, the signifcantly predominant metabolite was MTPG with three and gour residues of glutamic acid (the so-called long-chain), while 12 weeks after discontinuation, MTPG 2 was the predominant fraction.Conclusions. Low values of MTPG 3 and MTPG 4 with high values of MTPG 2 may indicate a recent initiation of treatment or MTB cancellation within the next 3 months. In the event of subjective adverse reactions (ADRs), it is advisable to consider the possibility of switching to a drug analogue of another manufacturer.

The human body burden of polychlorinated biphenyls in serum of residents in an area from Hubei Province

Concentrations of dioxin-like polychlorinated biphenyls (dl-PCBs) and non-dioxin-like PCBs (ndl-PCBs) in 26 serum samples of the residents from Hubei Province were analyzed via high-resolution gas chromatograph tandem high-resolution mass spectrometer (HRGC-HRMS) method. Total concentrations of twelve dl-PCBs (Σdl-PCBs) were in range of 366.30-4 945.77 pg/g fat, with the mean value (2 093.76 pg/g fat), and PCB 118 was the predominant congener. For six ndl-PCBs, total concentrations (Σndl-PCBs) were in range of 2 671.32-20 626.26 pg/g fat (mean 12 505.45 pg/g fat), and PCB 153 was the predominant congener. Mean concentration of Σdl-PCBs were significantly and positively associated with age (rs=0.574, P=0.002). The mean World Health Organization toxicity equivalent (WHO-TEQ) of dl-PCBs (ΣTEQdl-PCBs) were range from 0.07 to 8.69 pg/g fat.

A Dieldrin Case Study: Another Evidence of an Obsolete Substance in the European Soil Environment

Soil constitutes a central environmental compartment that, due to natural and anthropogenic activities, is a recipient of several contaminants. Among them, organochlorine pesticides are of major concern, even though they have been banned decades ago in the European Union, due to their persistence and the health effects they can elicit. In the presented work, a gas chromatographic tandem mass spectrometric (GC-MS/MS) developed method was applied to soil samples after the suspected and potential use of formulations containing organochlorine active substance. One soil sample was positive to dieldrin at 0.018 mg kg−1. Predicted environmental concentration in soil (PECsoil) considering a single application of this active substance potentially attributed the finding in its past use. The subsequent health risk assessment showed negligible non-carcinogenic risk and tolerable carcinogenic risk. The latter signifies that repetitive and prolonged sampling can unveil the pragmatic projection of persistent chemicals’ residues in the soil.

Analysis and formation of polycyclic aromatic hydrocarbons and cholesterol oxidation products in thin slices of dried pork during processing

This study aims to determine toxic compounds polycyclic aromatic hydrocarbons (PAHs) and cholesterol oxidation products (COPs) in thin slices of dried pork as affected by different flavorings and roasting temperature treatments through employing a QuEChERS method coupled with gas chromatograph–tandem mass spectrometer (GC-MS/MS) and gas chromatograph–mass spectrometer (GC-MS), respectively. By employing this method, high accuracy and precision was attained for freeze-dried pork hind leg sample. Following addition of 8 different flavorings with roasting temperature at 120, 160, and 200 °C, the levels of total COPs and PAHs in thin slices of dried pork followed a temperature-dependent increase during roasting, which was further confirmed by principle component analysis. High level of soy sauce or sugar inhibited COP formation, while the low-level minimized PAH formation in thin slices of dried pork during roasting. Sugar was more effective in inhibiting COP formation while soy sauce was more efficient in reducing PAH formation.

Method development for the determination of Synthetic Musks and Organophosphorus Pesticides in Human Adipose Tissue

Synthetic musks and organophosphorus pesticides represent a potential risk to the human health since exposure can lead to distinct types of carcinogenesis and endocrine disorders. These are lipophilic compounds as such, prone to deposit and persist in fat tissues, mainly in adipose tissue. Very few studies have reported on the occurrence and accumulation profile of these contaminants in human adipose tissue.Analytical methods for the detection and quantification of synthetic musks and organophosphorus pesticides in adipose tissue are lacking. In this study, the efficacy of different extraction with ultrasonic homogenizer and dispersive solid-phase extraction (d-SPE) clean-up methods were evaluated in human adipose tissue. The relative sample clean-up was assessed by measurement of total lipid content. The quantification of four synthetic musks and six organophosphorus pesticides were performed by gas chromatography (GC) mass spectrometry (MS) and flame photometric detection (FPD), respectively.The d-SPE clean-up with 50 mg PSA, 150 mg MgSO4, 100 mg C18EC and 50 mg Z-Sep provided the most effective clean-up, removing the greatest amount of interfering substances including lipids and simultaneously ensuring good chromatographic separation and recoveries. Method detection limits were between 4 to 9 ng/g for synthetic musk and 1 to 7 ng/g for organophosphorus pesticides in adipose tissue. The proposed method was applied to adipose tissue of obese patients and positive samples were confirmed with GC tandem mass spectrometry. Galaxolide was found in all the samples tested with concentrations ranging from 0.08 to 0.5 μg/g of adipose tissue. No other synthetic musk studied was detected. Organophosphorus pesticides were not found in the analysed samples.The developed analytical procedures were successful and can easily be applied to biomonitoring these compounds in human adipose tissue.

Association between maternal exposure to the pesticide dichlorodiphenyltrichloroethane (DDT) and risk of obesity in middle age.

Background:Obesity is a malnourishment epidemic worldwide. A meta-analysis of prospective human studies across the world demonstrated a consistent positive association between maternal exposure to the pesticide dichlorodiphenyltrichloroethane (DDT) and its metabolite dichlorodiphenyldichloroethylene (DDE) and children with obesity. The present study evaluates the association of maternal exposure to DDT and DDE with the risk of obesity in daughters during their mid-life in a prospective birth cohort with up to 53 years of follow-up.Methods:Gravidas’ blood was collected during their 1959–1967 enrollment into the prospective Child Health and Development Studies birth cohort in California. Their daughters aged 44–53 years had their height, weight, and waist circumference measured during a home visit to evaluate associations of daughters’ adiposity and relative risk of overweight and obesity with their mothers’ prenatal serum levels of DDT and DDE quantified by gas chromatograph-tandem mass spectrometer (n=511).Results:Maternal o,p’-DDT was positively associated with body mass index (beta=0.59 kg/m2 per ln ng/ml (95th percentile confidence interval, 95CI: 0.17, 1.00)) and waist circumference (beta=1.19 cm per ln ng/ml (95CI: 0.26, 2.13)) in multivariable models. Maternal o,p’-DDT was positively associated with a 26% (95CI: 6–49%) to 31% (95CI: 6–62%) higher risk of overweight and the same magnitude of additional risk for obesity, based on waist circumference and BMI definitions respectively, in multivariable models.Conclusions:These data indicate maternal DDT exposure is significantly associated with increased obesity risk among middle-aged women independent of the obesity definition, confounding, and obesity risk factors. Our findings suggest that policies supporting the use of DDT for malaria vector abatement need to consider the obesity risk as a health cost when weighing the benefits of using DDT in malaria vector control.

The pollution profiles and human exposure risks of chlorinated and brominated PAHs in indoor dusts from e-waste dismantling workshops: Comparison of GC–MS, GC–MS/MS and GC × GC–MS/MS determination methods

The toxicities of some chlorinated and brominated polycyclic aromatic hydrocarbons (X-PAHs) are higher than their corresponding parent PAHs. However, the identification and quantitation of X-PAHs in environment are still changeable and limitedly reported. To develop a robust method for routine analysis of X-PAHs in environmental samples, the determination of 34 X-PAHs was performed and compared using different instruments, including gas chromatography-mass spectrometry (GC–MS), gas chromatography-tandem mass spectrometry (GC–MS/MS) in both electron ionization (EI) and negative chemical ionization (NCI) modes, and comprehensive two-dimensional gas chromatograph-tandem mass spectrometer (GC × GC–MS/MS). GC-EI-MS/MS possessed the highest sensitivity with method detection limits of 2.00–40.0 and 2.00–20.0 pg/g dry weight (dw) for Cl-PAHs and Br-PAHs, respectively. This validated method was then applied to analyze X-PAHs in indoor dusts from a typical e-waste dismantling workshop, and the concentrations of Σ18Br-PAHs (8.80–399 ng/g dw) were higher than Σ16Cl-PAHs (7.91–137 ng/g dw). The toxicity equivalency quantities (TEQs) of Cl-PAHs at e-waste dismantling workshop and Br-PAHs at raw materials crushing workshop showed the highest values of 176 and 453 pg·TEQ/g, respectively. Cl-PAHs and Br-PAHs posed a potential health risk to workers through dust ingestion in workshops. Further attention should be payed to the formation mechanism of X-PAHs and the health risk.

New fully automated gas chromatographic analysis of urinary S-phenylmercapturic acid in isotopic dilution using negative chemical ionization with isobutane as reagent gas.

The determination of urinary S-phenylmercapturic acid (S-PMA) represents the most reliable biomarker to monitor the intake risk of airborne benzene. Recently, the European Chemical Agency deliberated new occupational exposure limits for benzene and recommended an S-PMA biological limit value of 2-μg/g creatinine. This limit is an order of magnitude lower than the previous one, and its determination constitutes a challenge in the analytical field. We developed and validated a method that allows the fully automated and sensitive determination of S-PMA by the use of gas-chromatography negative chemical ionization tandem mass spectrometry in isotopic dilution. For negative chemical ionization, we selected a mixture of 1% isobutane in argon as reactive gas, by studying its chemical ionization mechanism and optimal parameters compared with pure isobutane or pure methane. This gas mixture produces a more abundant signal of the target analyte than isobutane or methane, and it extended the operative lifetime of the ion source, enabling us to start a high-throughput approach of the S-PMA analysis. Moreover, energy-resolved mass spectrometry experiments were carried out to refine the MS/MS analysis conditions, testing nitrogen and argon as collision gases. The method optimization was pursued by a chemometric model by using the experimental design. The quantification limit for S-PMA was 0.10 μg/L. Accuracy (between 98.3% and 99.6%) and precision (ranging from 1.6% to 6.4%) were also evaluated. In conclusion, the newly developed assay represents a powerful tool for the robust, reliable, and sensitive quantification of urinary S-PMA, and because of its automation, it is well suited for application in large environmental and biological monitoring.

Development of a Robust and Sensitive Method for Analyzing Butyltins, Phenyltins and Octyltins in Seafood

A new method has been developed and validated for determination of ten organotin compounds (OTCs), including butyltins, octyltins, phenyltins, and tricyclohexyltin, in seafood that preserved the moiety of individual OTCs. The optimized method started with extraction of OTCs by acidified methanol solution and then cleaned up with Florisil solid-phase extraction (SPE). The OTCs in extract were finally derivatized with sodium tetraethylborate. The instrumental determination was carried out by a gas chromatograph coupled to an inductively coupled plasma mass spectrometer (GC-ICP/MS). Besides, gas chromatograph tandem mass spectrometry was also studied and evaluated for OTCs’ sensitivities. The method was validated with various seafood samples, including fishes, crustaceans and mollusks, according to Eurachem guidelines. An adequate linear relationship was obtained in the studied concentration range (0.125–12.5 μg Sn kg−1) in samples; the average spiked recovery values were in the range of 70–120% for the three levels of concentration studied in samples: 1.0, 1.5, and 2.0 μg Sn kg−1. Precision values, expressed as relative standard deviation, were lower than 10% at aforementioned spiking levels. The detection limits and quantification limits were below or equal to 0.25 and 1.0 μg Sn kg−1, respectively. Besides, certified reference material was used to assess the accuracy of the developed method. The developed method was successfully applied for the OTC determination in real samples.

Evidence of sulfur mustard exposure in victims of chemical terrorism by detection of urinary β-lyase metabolites

Background: Sulfur mustard (SM) is a vesicant chemical warfare agent. Ocular, dermal, and respiratory systems are the primary targets of SM exposure. The aims of this study were to perform a quantitative analysis of β-lyase metabolites of SM as 1,1′-sulfonylbis[2-(methylthio) ethane] (SBMTE) in urine samples of chemical casualties and to investigate the relationship between the measured SBMTE levels and the severity of characteristic symptoms of SM poisoning.Methods: A bioanalytical method which is based on titanium (III) chloride reduction of β-lyase metabolites was employed to analyze urine samples of individuals (n = 13, collected 30 h after SM exposure) using gas chromatography-tandem mass spectrometry.Results: Various levels of SBMTE were measured in urine samples of seven individuals, confirming SM exposure for each. There was a correlation observed between measured levels of SBMTE in human urine samples and severity of clinical findings including ocular, respiratory, and cutaneous lesions of SM.Discussion: In combination with clinical examination, measurement of SBMTE levels in human urine could be used as a prognostic factor for clinical outcomes in victims of SM exposure. This bioanalytical verification is also important for the documentation of alleged use of SM.Conclusion: SBMTE is an unambiguous biomarker of potential SM poisoning as it does not exist in urine samples of an unexposed population. Quantitation of urinary SBMTE concentrations in victims of SM could be used in order to enable improved interpretation of clinical findings.

Impact of Piper betle leaf extract on grape downy mildew: effects of combining 4-allylpyrocatechol with eugenol, α-pinene or β-pinene

Methanol extract of Piper betle leaves exhibited an inhibitory effect on grape downy mildew. This extract might contain more than two compounds which have different polarities that suppress grape downy mildew. Gas chromatograph-tandem mass spectrometry analysis identified 4-allylpyrocatechol, eugenol, α-pinene, and β-pinene in the methanol extract. Neither of the compounds suppressed grape downy mildew by single treatment. On the other hand, treatment with a combination of 4-allylpyrocatechol with eugenol, α-pinene or β-pinene enhanced the inhibitory effects on grape downy mildew and perfectly suppressed it. The complex extracted from P. betle leaves may be used in organic agriculture as an alternative to chemical fungicides in viticulture.

Determinations of Triclosan and Parabens in Household Dusts by Solid-Phase Microextraction with Microwave Assisted Extraction

Indoor dust has been known as a sink for many semi-volatile organic compounds, such as triclosan and parabens. Since indoor environment can protect dust from sunlight, rain and biological degradation, pollutants then could be persistent and accumulated in the residential environment. Up to now, the analysis of triclosan and parabens in dust is solvent and time consuming. Therefore, a method for the measurement of triclosan and parabens in dusts simultaneously by using microwave assisted direct-immersion solid-phase microextraction (MAE-DI-SPME) has been developed to determine the distributions in Taiwan. In this study, commercial vacuum cleaner was used to collect household dusts while particles with diameter smaller than 150&amp;#956;m were filtered out by stainless mesh. Afterwards, 0.02g dust sample was spiked with 2.5 &amp;#956;g/g of surrogate in a 4mL vial and stood for overnight. RO water of 2.5mL was added into the sample the next day, followed by the filtration and MAE-DI-SPME extraction procedures. Gas chromatograph-tandem mass spectrometer (GC/MS/MS) was employed for the analysis. Several parameters affecting the SPME extraction efficiency were optimized. The results showed that the desorption efficiency was 100% when the desorption time was 20 min under 250 degree C. The best suitable fiber coating was 65&amp;#956;m PDMS/DVB and the optimum condition of MAE-DI-SPME for extraction of triclosan and parabens in dust was 20 minutes at 80 degree C. For indoor dust samples in Taiwan, the median, mean and rage of triclosan and paraens concentrations were determined, respectively. Relatively to headspace extraction, the established method of MAE-DI-SPME for the measurements of triclosan and parabens in indoor dust provides good linearity and precisions. Besides, compared with traditional extraction methods, the MAE-DI-SPME provides a time saving, easy for operation and solvent-free procedure.