Gas Chromatography-ion Trap Mass Spectrometry Research Articles

HS-SPME/GC-MS methodologies for the analysis of volatile compounds in cork material

Two methods based on headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography–ion trap mass spectrometry (GC-IT/MS) were proposed for the analysis of volatile organic compounds (VOCs) in cork material used in the production of cork stoppers. The effect of various factors affecting the extraction efficiency was carried out by means of a 24 full factorial design. The first method allowed the extraction of 17 terpenes by using a divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fiber (50/30 μm). The optimal conditions were achieved when cork extract (5 mL) added with 2.3 g of NaCl was extracted during 35 min at 55 °C. The second method allowed the identification of 41 carbonyl compounds after in-solution (5 mL) derivatization with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA, 2.3 mg/mL), followed by an incubation period of 6 min at 52 °C and extraction during 36 min at the same temperature, using a PDMS/DVB (50/30 μm) fiber. Both methods are simple, solvent free and fast. These methods were applied to the analysis of different cork raw material showing significant differences in the amounts of volatile compounds analyzed. Alcanfor and α-terpineol were the terpenes compounds present at highest amounts, and within carbonyl compounds analyzed, some samples presented a high level of butanal, octanal, nonanal, and glyoxal.

Fast analysis of nine PAHs in beer by ultrasound-vortex-assisted dispersive liquid–liquid micro-extraction coupled with gas chromatography-ion trap mass spectrometry

An Ultrasound-Vortex-Assisted Dispersive Liquid–Liquid Micro-Extraction (USVADLLME) procedure coupled with Gas Chromatography-Ion Trap Mass Spectrometry (GC-IT/MS) is proposed for the fast analysis of nine polycyclic aromatic hydrocarbons in beer.

A methodological approach to the selection of liquid reagents for chemical ionization ion trap-gas chromatography mass spectrometry: A case study of GBL and 1,4-BD

A new approach is proposed for the selection of reagent ion species in a gas chromatography-chemical ionization mass spectrometry (GC-PICI-MS) method for GBL and 1,4-BD determination, the two “prodrugs” of gamma-hydroxybutyric acid (GHB), a drug associated with sexual assault. The GC-PICI-MS is often the best technique to avoid an extended fragmentation occurring in EI source and it preserves the information on molecular ions. Ion-trap mass spectrometry (IT-MS) is a valuable tool in chemical ionization experiments, commonly affording reaction times 104–105 higher than those in conventional CI sources. This feature allows the use of either vapors from liquid reagents, or many reactant species that are difficult to generate and employ in the conventional CI experiments. In this research acetone, acetonitrile, methanol and diethylamine were evaluated to generate vapors of the chemical ionization species. The use of liquid CI reagent offers a wide range of chemical–physical properties that can greatly affect the specificity, with the possibility to modulate the detection of the analyte in comparison with background or matrix interferences. The experimental data using different CI liquid reagents and reaction times were compared through calibration curves of GBL and 1,4-BD (ranging from 10 to 1000ng/mL). The linear regression curves obtained were used to calculate the sensitivity (slope) and limit of detection (LOD) of the method. Methanol resulted in the most efficient reagent for the determination of studied analytes. However, its employment as ionization agent of the 1,4-BD favors the hydride abstraction mechanism or hydrogen loss from protonated-molecule ions. These phenomena can be considered as a possible sources of uncertainty or errors. Therefore, acetonitrile can be employed as a good compromise between sensitivity and reliability of signal for both analytes.

Visible light caffeic acid degradation by carbon-doped titanium dioxide.

The removal of the phenolic compound, caffeic acid, by photodegradation has been investigated using carbon-doped titanium dioxide particles as a photocatalyst under visible light. UV-vis absorption spectroscopy and gas chromatography-ion trap mass spectrometry analyses revealed a substrate concentration dependence of the removal of caffeic acid from a water solution. The k2 and t(0.5) parameters of each reaction were calculated by fitting kinetics data to a second-order kinetic adsorption model. To evaluate the photodegradation event, the effect of the adsorption process on the whole degradation was also monitored in the absence of light. Adsorption isotherm studies supported by ζ potential and scanning electron microscopy data demonstrated the pivotal role of the absorption mechanism. It was found that the whole photodegradation process is governed by a synergic mechanism in which adsorption and photodegradation are involved. This study, centered on the removal of caffeic acid from aqueous solutions, highlights the potential application of this technology for the elimination of phenolic compounds from olive mill wastewater, a fundamental goal in both the agronomical and environmental fields.

An experimental investigation into the atmospheric degradation of piperazine

The atmospheric degradation of piperazine was investigated using an indoor smog chamber. Experiments were carried out in the presence of nitrogen oxides (NOx), ozone or nitric acid. Piperazine reacted rapidly under all evaluated conditions: irradiated in the presence of NOx and with ozone and nitric acid in the dark. Gas phase products from the oxidation of piperazine were identified by infrared spectroscopy, DNPH cartridges followed by HPLC analysis, and by sampling chamber gas through Tenax sorbent material followed by analysis using thermal desorption GC-ITMS (gas chromatography ion trap mass spectrometry).Eight compounds were positively identified, with a further nine compounds tentatively identified using GC–MS based on molecular weight and mass spectra. Ammonia formation was observed from piperazine oxidation, and its formation was from the subsequent reactions of photooxidation products of piperazine rather than directly from the reaction of piperazine. The nitrosamine and nitramine expected from piperazine, N-nitrosopiperazine, and N-nitropiperazine, were both identified and confirmed using 15NO, with a tentative maximum yield of nitrosamine of less than 5% observed.Aerosol yields, relative to total piperazine reacted not including that which absorbed to the walls, were considerably high but were not able to be quantified absolutely due to unusual behaviour of the scanning mobility particle sizer instrument to aerosol containing amines. The reaction of piperazine with gas phase nitric acid gave rise to immediate formation of aerosol.

Screening of By-Products of Esfenvalerate in Aqueous Medium Using SBSE Probe Desorption GC-IT-MS Technique

The pyrethroids, their metabolites and by-products have been recognized as toxic to environment and human health. Despite several studies about esfenvalerate toxicity and its detection in water and sediments, information about its degradation products is still scanty. In this work, esfenvalerate degradation products were obtained by chemical oxidation with hydrogen peroxide and their structure was elucidated using a procedure known as stir bar sorptive extraction (SBSE) probe desorption gas chromatography-ion trap mass spectrometry (GC-IT-MS) analysis. This procedure consists of the thermal desorption of analytes extracted from a SBSE stir bar introduced by a probe into a gas chromatograph (GC) coupled to an ion trap mass spectrometry (IT-MS) system. Based on IT-MS data, a degradation pathway of esfenvalerate is proposed with ten products of chemical oxidation of esfenvalerate that are fully identified. Among these compounds, 3-phenoxybenzoic acid and 3-phenoxybenzaldehyde were detected, reported as being environmental metabolites of some pyrethroids, with endocrine-disrupting activity.

Semen quality and the level of reproductive hormones after environmental exposure to pyrethroids.

The aim of this study was to determine whether the environmental exposure to pyrethroids affects semen quality and the level of reproductive hormones in men. The study population consisted of 334 men who attended the infertility clinic for diagnostic purposes and who had normal semen concentration of 15 to 300 mln/mL. Participants were interviewed and provided a semen sample. The pyrethroids metabolites-3-phenoxybenzoic acid (3PBA), cis-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (CDCCA), trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (TDCCA), and cis-2,2-dibromovinyl-2,2-dimethylcyclopropane-1-carboxylic acid (DBCA) were analyzed in the urine using a validated gas chromatography ion-trap mass spectrometry method. Urinary pyrethroids metabolites levels were significantly associated with an increase in the percentage of sperm with abnormal morphology and decrease in sperm concentration, the level of testosterone, and computer-aided semen analysis parameters. Environmental pyrethroids exposure may affect semen quality and the level of reproductive hormones.

Fast determination of phthalate ester residues in soft drinks and light alcoholic beverages by ultrasound/vortex assisted dispersive liquid–liquid microextraction followed by gas chromatography-ion trap mass spectrometry

An ultrasound/vortex assisted dispersive liquid–liquid microextraction (USVADLLME) procedure coupled with gas chromatography–ion trap mass spectrometry (GC-IT-MS) is proposed for the rapid determination of seven phthalate esters in soft drinks and light alcoholic beverages (up to 6% alcohol by volume). Under the optimum conditions, the enrichment factors of the seven phthalate esters ranged from 205-fold to 315-fold for soft drinks and from 172-fold to 285-fold for light alcoholic beverages. The recoveries varied between 94.2% and 99.6% for soft drinks and 95.6% and 99.4% for light alcoholic beverages. The limits of detection were between 0.03 and 0.10 pg μL−1 and the limits of quantification were between 0.11 and 0.28 pg μL−1. The intra-day and inter-day precision expressed as the relative standard deviation varied between 2.9% and 5.1% and between 5.5% and 7.6%, respectively. The proposed USVADLLME-GC-IT-MS method was demonstrated to be simple, reproducible and practical for the determination of trace amounts of seven phthalate esters in soft drinks and light alcoholic beverages.

Several transport systems contribute to the intestinal uptake of Paraquat, modulating its cytotoxic effects

Paraquat (PQ) is an extremely toxic herbicide upon oral ingestion that lacks a specific antidote. In case of intoxication, treatment primarily relies on limiting its intestinal absorption. In this study, we elucidate the intestinal transport mechanisms of PQ uptake using Caco-2 cells as a model of the human intestinal epithelium. The cells were incubated with a wide range of PQ concentrations (0–5000μM) for 24h with or without simultaneous exposure to different transporters substrates/inhibitors including, choline or hemicolinium-3 (for choline carrier-mediated transport system inhibition) and putrescine, trifluoperazine, valine, lysine, arginine or N-ethylmaleimide (for basic amino acid transport systems inhibition). PQ cytotoxicity was evaluated by the MTT reduction assay and correlated with PQ intracellular levels quantified by gas chromatography-ion trap-mass spectrometry (GC–IT/MS). Potential interactions of PQ with the substrates/inhibitors of the transport systems were investigated and discarded by infrared spectroscopy.Our results showed a significant reduction in PQ intracellular accumulation and, consequently, in PQ cytotoxicity, in the presence of both choline and hemicolinium-3, demonstrating that the choline carrier-mediated transport system is partially involved in PQ intestinal uptake. Likewise, PQ cytotoxicity and intracellular accumulation were significantly attenuated by simultaneous exposure to putrescine, trifluoperazine, valine, lysine, arginine and N-ethylmaleimide. These data suggested the involvement of more than one of the basic amino acids transport systems, including the y+, b0,+ or y+L systems.In conclusion, this study demonstrated that several transport systems mediate PQ intestinal absorption and, therefore, their modulation may provide alternative efficient pathways for limiting PQ toxicity in intoxication scenarios.

Optimization of the QuEChERS Method for Determination of Pesticide Residues in Chicken Liver Samples by Gas Chromatography-Mass Spectrometry

The goal of this research was to evaluate the application of Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) method for the determination of organochlorine, organophosphate, and carbamate pesticides in fatty animal matrices such as liver of chicken obtained from National Research Institute of Animal Production in Balice (Poland). Pesticides extraction effectiveness was evaluated at two different spiking levels (0.010 and 0.020 mg kg−1) and efficiency of the dispersive solid-phase extraction (d-SPE) clean-up step was evaluated by comparison adding different d-SPE sorbent combinations (PSA + GCB, PSA + C18, PSA + SAX, and PSA + NH2). The analysis of pesticide residues was performed by gas chromatography ion trap mass spectrometry (GC/IT-MS). The linear relation was observed from 0 to 400 ng mL−1 and the determination coefficient R 2 > 0.997 in all instances for all target analytes. Better recoveries were obtained in samples at 0.020 mg kg−1 spiking level. The recoveries were in the range 70–120 %, with relative standard deviation (RSD) values lower than 15 % at 0.020 mg kg−1 spiking level for most pesticides. Similar recovery ratios were obtained with the four different combinations of sorbents tested in the clean-up step, with better precision when the (PSA + SAX) combination was tested. Limits of detection (LODs) ranged from 0.001 to 0.005 mg kg−1 and limits of quantification (LOQs) ranged from 0.003 to 0.015 mg kg−1. The proposed method was successfully applied analyzing pesticide residues in real chicken liver samples; detectable pesticide residues were observed, but in all of the cases, the contamination level was lower than the default maximum residue levels (MRLs) set by European Union (EU), Regulation (EC) N 396/2005.

Elimination of Transamination during Chloroform Fumigation to Determine Uptake of Labeled Amino Acids by Soil Microorganisms

Compound specific stable isotope analysis combined with chloroform fumigation extraction was used to investigate amino acid utilization by soil microorganisms. Double‐labeled glycine and L‐leucine (98% 13C2, 99% 15N) were added together with ammonium to soil samples. The concentration of amino acids was determined by ion trap gas chromatography–mass spectrometry (GC‐MS). In preliminary tests, the concentration of double‐labeled leucine in fumigated samples was lower than in the unfumigated control, even when the samples were extracted or fumigated immediately after its addition. At the same time, the concentration of single‐labeled leucine increased. Tests revealed that enzymes, released into soil solution during fumigation, replaced the labeled amino group of leucine with an unlabeled one taken from other organic molecules. The addition of sodium dodecyl sulfate to soil samples before fumigation stopped the interference by these enzymes. The proposed method allows determining the uptake of intact amino acids by soil microorganisms.

Analysis of volatile human urinary metabolome by solid-phase microextraction in combination with gas chromatography–mass spectrometry for biomarker discovery: Application in a pilot study to discriminate patients with renal cell carcinoma

A new and simple analytical approach consisting of headspace-solid phase microextraction (HS-SPME) sampling coupled with gas chromatography-ion trap/mass spectrometry (GC-IT/MS) was developed to study the volatile human urinary metabolome. A central composite design (CCD) was used in the optimisation of extraction conditions. Fibre selection and evaluation of pH influence were performed using an univariate mode and the influence of other parameters, such as the time and temperature of extraction, time of incubation and salt addition, that affect the efficiency of the SPME sampling, was carried out using a CCD. With a sample volume of 2mL, the optimal conditions in terms of total response values and reproducibility were achieved by performing analyses with a divinylbenzene/polydimethylsiloxane (DVB/PDMS) fibre, in an acidic pH (pH 2) with the addition of 0.59g of NaCl, allowing the sample to equilibrate for 9min and extracting at 68°C for 24min. The applicability of the optimised method was then tested in a pilot non-target analysis of urine samples obtained from patients with renal cell carcinoma (RCC) and healthy individuals. Chemometric unsupervised analyses performed on the volatile pattern acquired for these samples clearly showed the potential of volatile urinary metabolome to discriminate between RCC and control patients.

Determination of cis-permethrin, trans-permethrin and associated metabolites in rat blood and organs by gas chromatography–ion trap mass spectrometry

An analytical method was developed to measure cis-permethrin and trans-permethrin in different biological rat matrices and fluids (whole blood, red blood cells, plasma, brain, liver, muscle, testes, kidneys, fat and faeces). The method was also suitable for the simultaneous quantification of their associated metabolites [cis-3-(2,2-dichlorovinyl)-2,2-dimethyl-(1-cyclopropane) carboxylic acid (cis-DCCA), trans-3-(2,2-dichlorovinyl)-2,2-dimethyl-(1-cyclopropane) carboxylic acid (trans-DCCA) and 3-phenoxybenzoic acid (3-PBA)] in blood (whole blood, red blood cells, plasma) and liver. The target analytes were derivatised in samples using a methanolic/hydrochloric acid solution and then extracted with toluene. The analysis was performed by gas chromatography, and detection using ion trap tandem mass spectrometry. The selectivity obtained for complex matrices such as rat organs allowed the use of a purification step to be avoided for most of the matrices investigated. In the case of fat, where permethrin is suspected to accumulate, a dedicated purification step was developed. In fluids, the limits of quantification were at the 50 ng/mL level for the parent compounds and 3-PBA and at 25 ng/mL for cis-DCCA and trans-DCCA. For solid matrices excluding fat, the limits of quantification ranged from 50 ng/g for muscle to 100 ng/g for brain and testes for both cis-permethrin and trans-permethrin. The extraction recoveries ranged primarily between 80 and 120% for the matrix tested. The stability of blood samples was tested through the addition of 1% v/v formic acid. The methods developed were applied in a toxicokinetic study in adult rats. cis-Permethrin and the metabolites were detected in all corresponding matrices, whereas trans-permethrin was detected only in blood, plasma and faeces.

Microwave-Assisted Extraction/Dispersive Liquid–Liquid Microextraction Coupled with DSI-GC-IT/MS for Analysis of Essential Oil from Three Species of Cardamom

A novel method of microwave-assisted extraction coupled with polyethylene Pasteur-pipette-based dispersive liquid–liquid microextraction applying low-density organic solvent (MAE-LDS-DLLME) was successfully developed for extraction and preconcentration of essential oil from three species of cardamom (Semen Alpiniae Katsumadai, Fructus Amomi Rotundus, and Semen Myristicae). The essential oil was analyzed by gas chromatography-ion trap/mass spectrometry (GC-IT/MS) using a ChromatoProbe direct sample introduction (DSI) device. The effects of various parameters affecting the extraction process, such as the type of extraction solvent and dispersive solvent, ionic strength, microwave power, and irradiation time, were investigated thoroughly and optimized. The optimal conditions were extraction solvent of toluene, dispersive solvent of methanol, microwave power of 80 W, irradiation time of 4.0 min, plant material amount of 0.1 g, and no addition of salt. Compared with hydrodistillation, MAE-DLLME-DSI-GC–MS is a simple, rapid, low-cost, efficient, and environmentally friendly method, and the essential oil contains higher amounts of oxygenated compounds, which play an important and valuable role in terms of their contribution to the fragrance of the essential oil. In this work, we also studied the main components of the three varieties of cardamom. Qualitative and quantitative differences in the components of the three essential oils were found to be present. Based on comparison of the main bioactive compounds of essential oil, a significant difference was found between Semen Alpiniae Katsumadai or Fructus Amomi Rotundus and Semen Myristicae. This study also provides a new approach for quality assessment of traditional Chinese medicines.

Correlation between amino acid racemization and processing conditions for various wheat products, oil seed press cakes and lignin samples

The occurrence of d-amino acids in native and processed plant products is brought into context with the harshness of their treatment condition. It was found that already a small increase in processing harshness such as the milling efficiency of wheat straw or the increased pressure and duration of pumpkin seed oil extraction leads to traceable changes in the overall amino acid content as well as the racemization rate of free and protein bound amino acids. In the top position of our process harshness scale lies the strong alkali and heat-induced extraction of polyphenolic compound lignin from wood and other cellulose-rich plant fibers, e.g. wheat straw, during paper production. Since lignin accumulates in large quantities and its transformation into value-added “bio” products necessitates the recovery of native, functionally preserved lignin, milder pulping methods gain increasing interest. An unexpected drawback of such mild extraction conditions is however the high nitrogen content of such lignin products, which further increase with increasing mildness of the pulping procedure. The presence of amide bands in the FT-IR spectra of such mildly processed lignin has revealed that this nitrogen originated from co-extracted proteins and peptides. The total amino acid content as well as the free amino acid content and the degree of racemization was determined by gas chromatography–ion trap mass spectrometry (GC–Iontrap MS) employing enantiomer labeling for quantification. Cross-determination of the average amino acid content was calculated from nitrogen values obtained by elemental analysis and correlation factors were calculated from measured and calculated data. Since those amino acids with two chiral centers, such as isoleucine, threonine and hydroxyproline exhibit the highest possible diversity in terms of their relative amount to one another as well as their internal enantiomer distribution, this set of two-centered amino acids provided very distinct amino acid pattern, which proofed to be characteristic for the type of plant material as well as the harshness of the different processing conditions.

Non-targeted and targeted analysis of wild toxic and edible mushrooms using gas chromatography–ion trap mass spectrometry

Mushrooms are known all over the world both due to the remarkable gastronomic value of some species and for severe intoxications mediated by other species that are frequently difficult to distinguish from the edible ones, by the common user. Therefore, it is important to develop strategies to discover molecules that can identify mushroom species. In the present work, two GC-MS methodologies were applied in the chemical characterization of 22 mushroom species (12 edible, 3 toxic and 7 potentially toxic) - a multi-target procedure to simultaneously determine amino acids (AA), fatty acids (FA) and sterols by previous derivatization procedure with MSTFA, and a Head Space-Solid Phase Microextraction method to determine volatiles. For both methods, two approaches to data analysis were used: (I) targeted analysis, to identify and quantify AA, FA sterols and volatiles; (II) untargeted analysis, including Principal Component Analysis and Partial Least Square Discriminant Analysis, in order to identify metabolites/metabolite pattern with potential species identification and/or differentiation. Multi-target experiment allowed the identification and quantification of twenty one primary metabolites (9 AA, 11 FA and 1 sterol). Furthermore, through untargeted data analysis, it was possible to identify a 5-carbon sugar alcohol structure molecule, which was tentatively identified as xylitol or adonitol, with potential to be a species-marker of the edible Suillus bovinus mushrooms. Volatile profiling studies resulted in the identification of the main volatiles in mushrooms. Untargeted analysis allowed the identification of 6 molecules that can be species- or genus-specific: one secondary metabolite specific to the edible species Lycoperdon perlatum, an ester of hexanoic acid, tentatively identified as allyl or vinyl caproate; and five other secondary metabolites, whose identification was not achieved, which were only detected in Lactarius aurantiacus specimens (edibility/toxicity unknown).

Determination of 21 fragrance allergens in toys by gas chromatography-ion trap mass spectrometry

A method of gas chromatography-ion trap mass spectrometry (GC-IT-MS) was developed for the determination of 21 fragrance allergens in sticker toys, plush toys and plastic toys. The experimental conditions, such as sample pretreatment conditions, and the analytical conditions of GC-IT-MS, were optimized. The sticker toy samples and plush toy samples were extracted with acetone by ultrasonic wave, and the extracts were separated on an Agilent HP-1 MS column (50 m x 0.2 mm x 0.5 microm), then determined by IT-MS and quantified by external standard method. The plastic toy samples were extracted by the dissolution-precipitation approach, cleaned up with an Envi-carb solid phase extraction column and concentrated by rotary evaporation and nitrogen blowing, then determined by GC-IT-MS and quantified by external standard method. The calibration curves showed good linearity in the range of 0.002-50 mg/L with the correlation coefficients greater than 0.996 8. The limits of quantification (LOQ, S/N > 10) were 0.02-40 mg/kg. The average recoveries of the target compounds spiked in the sample at three concentration levels were in the range of 82.2%-110.8% with the relative standard deviations (RSDs) of 0.6%-10.5%. These results show that this method is accurate and sensitive for the qualitative and quantitative determination of the 21 fragrance allergens in the 3 types of toys.

Variability of urinary excretion of pyrethroid metabolites in seven persons over seven consecutive days—Implications for observational studies

Concentration of urinary metabolites is frequently used for biomonitoring of exposure to synthetic pyrethroids, the class of non-persistent insecticides. These chemicals are currently widely used in agriculture, households and public health all over the world. Most of them are easily metabolized in mammals and in the form of metabolites excreted in urine. The concentration in urine is thus susceptible to significant variations, even within a short period of time. In this study, temporal changes in urinary metabolites concentrations in seven subjects (four females and three males aged: 24–71) were monitored over seven consecutive days. All urine voids (281 in total) were collected and analyzed for cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-carboxylic acid (cis-Cl2CA and trans-Cl2CA), cis-3-(2,2-dibromo-vinyl)-2,2-dimethylcyclo-propanecarboxylic acid (Br2CA) and 3-phenoxybenzoic acid (3PBA) using a validated gas chromatography ion-trap mass spectrometry method. Only 3PBA was detectable in more than 60% of the collected samples enabling a reliable statistical analysis. Statistical analysis was performed to evaluate temporal variability in urinary excretion of 3PBA over the studied period. Both volume and creatinine (Cre) adjusted concentrations were evaluated with the latter one being the most reliable. Among all samples, first morning voids (FMV) were the least reproducible (interclass correlation coefficient – ICC, 0.551 and 0.350 for volume and creatinine adjusted concentrations, respectively). Spot and reconstructed 24-h samples were more reproducible in this study. ICC values for ng/mL concentrations were 0.599 and 0.681 (in spot and 24-h samples) and 0.846 and 0.796 for μg/g creatinine concentrations.Results of this study suggest fairly constant short-term exposure to pyrethroids metabolized to 3PBA among the urban population in Poland. Creatinine adjustment should be performed in epidemiological studies and spot or multiple spot samples should be preferentially collected for the highest reliability of the measurement.

Metabolite profiling of the short-term responses of rice leaves (Oryza sativa cv. Ilmi) cultivated under different LED lights and its correlations with antioxidant activities

Metabolite profiling of rice leaves (Oryza sativa cv. Ilmi) was performed to investigate the short-term responses to different light-emitting diode (LED) lights, blue (B), green (G), red (R), white (W), shade (S), by using gas chromatography–ion trap-mass spectrometry (GC–IT-MS) and ultra-performance liquid chromatography–quadrupole-time-of-flight-mass spectrometry (UPLC–Q-TOF-MS) with multivariate analysis. Clear grouping patterns of each light-grown sample, except G and W, were shown in partial least squares-discriminant analysis (PLS-DA). Thirty-two primary metabolites and eleven secondary metabolites were selected and visualized using heatmap. Antioxidant activities of rice leaves followed the order B=W=G>R>S and isoorientin-2′′-O-glucoside, isovitexin-2′′-O-glucoside, isoorientin-2′′-O-(6′′′-ρ-coumaroyl)-glucoside, and isoscoparin-2′′-O-glucoside showed similar relative differences and had higher Pearson's correlation coefficients than other metabolites in correlation network. According to the orthogonal projection to latent structures-discriminant analysis (OPLS-DA) between B and R, the levels of amino acids, organic acids, fatty acids, and flavonoid glycosides were relatively high in B, whereas the glucose and fructose levels were high in R.

Determination of N,N-dimethyltryptamine in beverages consumed in religious practices by headspace solid-phase microextraction followed by gas chromatography ion trap mass spectrometry

A novel analytical approach combining solid-phase microextraction (SPME)/gas chromatography ion trap mass spectrometry (GC-IT-MS) was developed for the detection and quantification N,N-dimethyltryptamine (DMT), a powerful psychoactive indole alkaloid present in a variety of South American indigenous beverages, such as ayahuasca and vinho da jurema. These particular plant products, often used within a religious context, are increasingly consumed throughout the world following an expansion of religious groups and the availability of plant material over the Internet and high street shops. The method described in the present study included the use of SPME in headspace mode combined GC-IT-MS and included the optimization of the SPME procedure using multivariate techniques. The method was performed with a polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber in headspace mode (70min at 60°C) which resulted in good precision (RSD<8.6%) and accuracy values (71–109%). Detection and quantification limits obtained for DMT were 0.78 and 9.5mgL−1, respectively and good linearity (1.56–300mgL−1, r2=0.9975) was also observed. In addition, the proposed method showed good robustness and allowed for the minimization of sample manipulation. Five jurema beverage samples were prepared in the laboratory in order to study the impact of temperature, pH and ethanol on the ability to extract DMT into solution. The developed method was then applied to the analysis of twelve real ayahuasca and vinho da jurema samples, obtained from Brazilian religious groups, which revealed DMT concentration levels between 0.10 and 1.81gL−1.