Mass Selective Detector Research Articles

Investigation of volatile organic compounds emitted by Anoplophora glabripennis (Moschulsky) using thermal desorption and gas chromatography-mass spectrometry

Volatile organic compounds (VOCs) from alive Anoplophora glabripennis (ALB) imagoes, larvae and ovipositions were obtained by enrichment on adsorbents. They were analysed qualitatively by thermal desorption coupled with gas chromatography and a mass selective detector. All together 229 substances were identified: 34 from larvae, 19 from imago and 176 from oviposition. Ovipositions of two generations were analysed, both over an 8 week period with focus on aging and repeatability. (+)-α-Longipinene occurred in 100%, (+)-Cyclosativene and α-Cubebene in 99% of all oviposition measurements. 1R-α-Pinene occurred in 100% of all imago measurements. 2,4-Dimethyl-1-Heptene and (+)-Cyclosativene were detectable in all three ALB sample types.

Modern Instrumental Limits of Identification of Ignitable Liquids in Forensic Fire Debris Analysis

Forensic fire debris analysis is an important part of fire investigation, and gas chromatography–mass spectrometry (GC-MS) is the accepted standard for detection of ignitable liquids in fire debris. While GC-MS is the dominant technique, comprehensive two-dimensional gas chromatography–mass spectrometry (GC×GC-MS) is gaining popularity. Despite the broad use of these techniques, their sensitivities are poorly characterized for petroleum-based ignitable liquids. Accordingly, we explored the limit of identification (LOI) using the protocols currently applied in accredited forensic labs for two 75% evaporated gasolines and a 25% evaporated diesel as both neat samples and in the presence of interfering pyrolysate typical of fire debris. GC-MSD (mass selective detector (MS)), GC-TOF (time-of-flight (MS)), and GC×GC-TOF were evaluated under matched conditions to determine the volume of ignitable liquid required on-column for correct identification by three experienced forensic examiners performing chromatographic interpretation in accordance with ASTM E1618-14. GC-MSD provided LOIs of ~0.6 pL on-column for both neat gasolines, and ~12.5 pL on-column for neat diesel. In the presence of pyrolysate, the gasoline LOIs increased to ~6.2 pL on-column, while diesel could not be correctly identified at the concentrations tested. For the neat dilutions, GC-TOF generally provided 2× better sensitivity over GC-MSD, while GC×GC-TOF generally resulted in 10× better sensitivity over GC-MSD. In the presence of pyrolysate, GC-TOF was generally equivalent to GC-MSD, while GC×GC-TOF continued to show 10× greater sensitivity relative to GC-MSD. Our findings demonstrate the superior sensitivity of GC×GC-TOF and provide an important approach for interlaboratory benchmarking of modern instrumental performance in fire debris analysis.

Biotechnology for remediation and restoring the ecological status of soil in the places of permanent disposition of the troops by oil-destructor preparation on the basis of the microbial-plant association

The object of the study is a preparation of ecotoxicant destructor based on bacterial strains of Pseudomonas fluorescens, Pseudomonas putida, Pseudomonas délhiensis and associations of nodule bacteria Rhizobium loti with Lotus corniculatus. It is established, that during the simultaneous use of the bacteria and the legume Lotus corniculatus the rate of oxidation of petroleum hydrocarbons increases three times in comparison with the degradation rate of the pollutant after the separate use of each bacterial strain. We have received the preparation of ecotoxicant destructor – dry heterogeneous mass consisting of viable microbial cells of strains of P. delhiensis and R. lotus, seeds of leguminous plant Lotus corniculatus and delignified sawdust. Oil destructive activity of the preparation is proved in the course of microfield experiments. The degradation of ecotoxicants is proved by capillary gas chromatography-mass spectrometry with mass-selective detection. Bacteria of the strains, included in the preparation, are non-pathogenic for humans and animals, biocompatible, environmentally safe, stable, unpretentious to nutritional needs, technological, do not persist in environmental objects in the absence of a substrate for destruction. The technology of the production of the preparation is developed. The results of these studies demonstrate the possibility of practical use of the degradative potential of the preparation in the course of the implementation of the measures for soil reclamation, cleaning up ecotoxicants and restoring its ecological status.

Rice Grain Quality Benchmarking Through Profiling of Volatiles and Metabolites in Grains Using Gas Chromatography Mass Spectrometry.

Gas chromatograph coupled with mass spectrometer is widely used to profile volatiles and metabolites from the homogenized rice flour obtained from mature grains. Rice grains consist of central endosperm which stores majorly starch and, in addition, accumulate various storage proteins as storage reserves. The outer nutritious aleurone layer stores lipids, sugar alcohols, volatiles, antioxidants, vitamins, and various micronutrients. Once paddy sample is dehulled, milled, and ground cryogenically, the brown rice flour is subjected to extraction of primary metabolites and volatiles using an appropriate extraction method. In metabolite profiling of the liquid extract obtained from the rice sample, mixture is initially subjected to methoxyamination then silylation before being subjected to untargeted metabolite profiling. Peaks obtained are processed for noise reduction and specific signal selection. Volatile compounds are initially extracted using a solid phase adsorbent prior to analysis. All these compounds, metabolites, and volatiles are detected in the mass selective detector by fragmentation at 70eV ionization energy and the resultant mass spectrum compared with a built-in library of compounds. Data mined from the gas chromatography mass spectrometry analysis are then subjected to post-processing statistical analysis.

Comparison of Chemical Composition and Antimicrobial Activity of Essential Oils Obtained from Different Cultivars and Morphological Parts of Lavandula angustifolia

The aim of the study was to compare the composition and antimicrobial activity of essential oils obtained from flowers and leafy stalks of two cultivars of Lavandula angustifolia: ‘Blue River’ and ‘Ellagance Purple’. Using gas chromatography with mass selective detector (GC-MS) method, 47 of their components were identified and quantified. The composition and activity of essential oils varied with the type of cultivar and the morphological part of the plant. The main components of essential oils obtained from flowers were: linalool, linalool acetate, lavandulol acetate and α-terpineol. Essential oils from leafy stalks contained mainly: borneol, epi-bicyclosesquiphellandrene, caryophyllene, eucalyptol and linalool. The significant inhibition of pathogenic microorganisms growth: S. aureus, P. aeruginosa and C. albicans was observed for all tested oils, but some important differences in their activity were found and compared to linalool. The relationship between the composition and biological activity was discussed.

Bioremediation of hexachlorocyclohexane (HCH) in soil using spent mushroom compost of Pleurotus ostreatus

Hexachlorocyclohexane (HCH), a highly chlorinated pesticide, was used worldwide in the 1950s and 1960s. HCH toxic residues are still detected in environmental compartments. Thus, effective, viable and eco-friendly strategy is required for its remediation. In this study, degradation of four HCH isomers was evaluated by amending contaminated soil using four treatments of spent mushroom compost (SMC) of Pleurotus ostraetus. The soil was incubated for 5 weeks and was sampled every seven days. Quantitative attenuation in HCH was calculated using gas chromatography–electron capture detector (GC-ECD) and metabolite was identified using gas chromatography–mass selective detector (GC-MSD). Maximum reduction 58%, 26%, 45%, and 64% for α-, β-, γ- and δ-HCH isomers, respectively, using SMC and soil (both unsterilized) showed that this treatment was the best for bioremediation of HCH in soil. However, when one of the factors, either soil or SMC, was sterilized, a significant reduction in HCH degradation was noticed. The second most reduction of isomers was seen during treatment where unsterilized SMC was added in sterilized soil followed by treatment where SMC was sterilized but soil was not. Abiotic control did not remove any significant quantities of HCH. Simple first-order (SFO) kinetic confirmed that SMC reduced the half-live manifolds as compared to biotic control. Only one metabolite δ-PCCH was identified during the course of study.

Elaboration of a method for the determination of low-molecular-weight mustard gas biomarkers in biological samples

The relevance of the development and the improvement of methods for the determination of metabolites (biomarkers) of toxic substances in biological fluids (blood, urine, etc.) is associated with the need to establish facts of humans and animals exposure to toxic chemicals. The need for such analysis arises within the framework of monitoring of the compliance with the provisions of the Chemical Weapons Convention (CWC), when conducting investigations into the alleged use of chemical agents, as well as within the framework of the official proficiency tests carried out by the Organization for the Prohibition of Chemical Weapons (OPCW). Nowadays there exists the problem of the determination of low-molecular-weight mustard gas biomarkers in biological samples with the use of gas chromatography methods with mass-selective detection. The low-molecular-weight biomarkers of sulfur mustard (SM) are thiodiglycol, oxides and sulfoxides. The identification and quantitative assessment of SM markers in blood and urine is carried out according to the methods, based on the displacement of thiodiglycol and its derivatives from protein conjugates with titanium trichloride, solid-phase extraction, concentration in ethyl acetate solution, derivatization with pentafluorobenzoyl chloride, heptafluorobutyrylimidazole, heptafluorobutyric acid anhydride or chloride, subsequent stripping of the derivative into the appropriate solvent and GH-MS analysis (chemical ionization technique with methane as a reagent gas with the registration of negative ions). After the sample preparation, the limits of detection of the minimum values ​​of ultra-low concentrations of the analyzed biomarkers of SM in urine and blood plasma were determined. After the chromatographic analysis, the corresponding graphs of indicators have been constructed, based on the concentrations of biomarkers in urine and blood plasma. Later on they have been used for the elaboration of the methods for the determination of SM biomarkers in human urine and blood.

Volatile compounds of Persian and Mexican lime associated with HLB (Huanglongbing) symptoms

The bacterium Candidatus Liberibacter asiaticus is the pathogen that causes the disease known as Huanglongbing (HLB) in citrus. During the course of the disease, the bacterium affects citrus plant phloem tissues, but their leaves remain asymptomatic for HLB for months to years after initial infection. This limits the early detection and control of the bacterium in infected trees. Therefore, in order to design a diagnostic strategy for HLB, the aim of this study was to quantify the abundance and concentration of the volatile compounds released from young shoots of the Persian lemon (Citrus latifolia Tanaka) and the Mexican lemon [Citrus aurantifolia (Christm.) Swingle] with and without HLB symptoms. The volatiles emitted by young shoots were captured by Solid Phase Microextraction (SPME) and analyzed in a gas chromatograph coupled to a mass selective detector (CG / MS). The results clearly indicate that young shoots with and without HLB symptoms released different abundances and concentrations of volatile compounds. The compounds: D-limonene, β-ocimene, and caryophyllene were collected at higher concentrations in the young shoots of both lemon species with HLB symptoms. This result shows the feasibility of designing a strategy for early detection of the disease in different species of lemon through recognition of patterns and concentrations of volatile compounds released from infected trees.

International descriptive and interventional survey for oxycholesterol determination by gas- and liquid-chromatographic methods

Increasing numbers of laboratories develop new methods based on gas-liquid and high-performance liquid chromatography to determine serum concentrations of oxygenated cholesterol metabolites such as 7α-, 24(S)-, and 27-hydroxycholesterol. We initiated a first international descriptive oxycholesterol (OCS) survey in 2013 and a second interventional survey 2014 in order to compare levels of OCS reported by different laboratories and to define possible sources of analytical errors. In 2013 a set of two lyophilized serum pools (A and B) was sent to nine laboratories in different countries for OCS measurement utilizing their own standard stock solutions. In 2014 eleven laboratories were requested to determine OCS concentrations in lyophilized pooled sera (C and D) utilizing the same provided standard stock solutions of OCS. The participating laboratories submitted results obtained after capillary gas-liquid chromatography-mass selective detection with either epicoprostanol or deuterium labelled sterols as internal standards and high-performance liquid chromatography with mass selective detection and deuterated OCS as internal standard. Each participant received a clear overview of the results in form of Youden-Plots and basic statistical evaluation in its used unit. The coefficients of variation of the concentrations obtained by all laboratories using their individual methods were 58.5–73.3% (survey 1), 56.8–60.3% (survey 2); 36.2–35.8% (survey 1), 56.6–59.8, (survey 2); 61.1–197.7% (survey 1), 47.2–74.2% (survey 2) for 24(S)-, 27-, and 7α-hydroxycholesterol, respectively. We are surprised by the very great differences between the laboratories, even under conditions when the same standards were used. The values of OCS's must be evaluated in relation to the analytical technique used, the efficiency of the ample separation and the nature of the internal standard used. Quantification of the calibration solution and inappropriate internal standards could be identified as major causes for the high variance in the reported results from the different laboratories. A harmonisation of analytical standard methods is highly needed.

The Degradation of O-ethyltoluene and 1,3,5-Trimethylbenzene in Lake Naivasha Wetland, Kenya.

The primary degradation of benzene derivatives in aquatic environments occurs via microbial and chemical processes. This study investigated the kinetic degradation of o-ethyltoluene and 1,3,5-trimethylbenzene in the wetland of Lake Naivasha. Sediment samples were collected from 6:00 AM to 6:00 PM at intervals of 3h during the dry season of December 2017. The sediment samples were air dried, ground into powder, followed by soxhlet extraction in a binary mixture of methanol and hexane in the ratio of 1:1. The extract was analyzed using gas chromatograph with mass selective detector. Variation in the concentrations of o-ethyltoluene and 1,3,5-trimethylbenzene with time was monitored kinetically. Accordingly, the half-lives for the degradation of o-ethyltoluene and 1,3,5-trimethylbenzene were 4.9 and 5.4h, respectively, and their corresponding decay rate constants were 3.93×10-5 and 3.56×10-5 S-1. 1,3,5-Trimethylbenzene was the most persistent contaminants in the wetland.

METHODOLOGICAL RECEPTION FOR DETERMINATION OF DICAMBA RESIDUES IN SOYBEANS BY GC-MS

Introduction. In this paper, there are presented results of investigations on the development and validation of the method for the determination of dicamba residues in import foodstuff (soybeans). The identification and quantitative determination of dicamba are performed by capillary gas-liquid chromatography with mass-selective detection (ionization-electron impact). Material and methods. The stages of sample preparation include four steps as extraction with acidified acetonitrile, followed by the filtration and evaporation; freezing the sample with filtration and evaporation; dissolving the dry residue in a mixture of acetone: water (1:20); purification by repeated redistribution in a system of immiscible solvents under varying the pH of the aqueous medium (pH 9-10: dichloromethane, hexane, pH 2: hexane-tert-butyl methyl ether). The chromatographic measurement was preceded by the derivatization of the acid to the corresponding methyl ester by the treatment with a solution of diazomethane in diethyl ether Results. The lower limit of the quantitative evaluation of dicamba in samples of soybean beans is of 0.01 mg/kg, the signal-to-noise ratio at the detection limit accounts of 20:1. The completeness of extraction of dicamba, established on the basis of analysis of model samples with the introduction of a substance at four points within the defined range, amounted to 85-95%. The average quadratic deviation of the repetition varies in the range of 3.3-4.9%. Discussion. The use of diethyl ether containing dibutylhydroxytoluene (6 ppm) as a stabilizer, as well as the interfering effect of phthalates, led to the formation of poorly resolved peaks of the methyl ester of dicamba, dibutylhydroxytoluene, and dibutyl phthalate. The combination of the use of different methods of data collection (in the scanning mode and in the mode of recording individual ions) made it possible to identify these components. Replacement of the used diethyl ether, as well as variation of chromatographic conditions, for separation of dicamba and phthalate peaks, made it possible to achieve the necessary selectivity of detection of the analyte.

INVESTIGATION OF COMPONENTS OF HEXANE EXTRACT FROM TAMARIX HISPIDA BY METHOD OF GAS CHROMATOGRAPHY

In this article, we determined the qualitative and quantitative component composition of the hexane extract, derived from plant material - the aerial part of the Tamarix hispida genus, the Tamarix family of Tamaricaceae, which grows in the southern region of the Republic of Kazakhstan (Almaty region). For this purpose, the previously dried and ground plant material (500 g) was extracted with hexane into the feed-reagent ratio (1:10) in a Soxhlet apparatus. The extract was concentrated under mild conditions (water bath temperature 40-45 °C) using a water-jet pump vacuum to concentrate. Analysis of the component composition of the hexane extract carried out using gas chromatography with a mass-selective detector under the following conditions: capillary column SHP-5MS used carrier gas helium with a flow rate of 1 ml / min at a temperature gradient from 40 °C to 250 °C and the injector volume - 0.2 μl. The materials were identified by mass spectra and retention times using the Wiley GC/MS library. The percentage of the components was calculated automatically from the areas of the peaks of the general chromatogram of the ions. As a result, 30 components were identified, of which 8 were acids and their esters, 5-alcohols, 4-ketones, 1-aldehyde, 1-phenol, 3-alkane, 3 halogen derivatives, 2-cyclic, 3-heterocyclic compounds. A significant content of β-carotene (23.73%), 2-cis-9-octadecinyl octaethanol (16.99%), propyl 3-octadecyloxyoleic acid (14.34%), octacosyltrifluoroacetate (8.60%), cis-11-octadecenoic acid (7.49%), heptacosan (6.01%), 2-bromocataladecan (5.24%), β-sitosterol (4.49%), respectively. Halogen-containing biologically active compounds were found for the first time in Tamarix genus. In addition, some amount of the nitrogen-containing compounds has been identified, which also were not previously found in lipophilic extracts of Tamarix.Forcitation:Ikhsanov Y.S., Abilov Z.A., Sultanova N.A., Choudhary M.I. Investigation of components of hexane extract from tamarix hispida by method of gas chromatography. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 6. P. 83-87

Online screening of acetylcholinesterase inhibitors in natural products using monolith-based immobilized capillary enzyme reactors combined with liquid chromatography-mass spectrometry

In order to develop a direct and reliable method for discovering lead compounds from traditional Chinese medicines (TCMs), a comparative online ligand fishing platform was developed using immobilized capillary enzyme reactors (ICERs) in combination with liquid chromatography-mass spectrometry (LC–MS). Methacrylate-based monolithic capillaries (400 μm I.D. × 10 cm) containing epoxy reactive groups were used as support to immobilize the target enzyme acetylcholinesterase (AChE). The activity and kinetic parameters of the AChE-ICER were investigated using micro-LC-UV. Subsequently, ligand fishing and identification from mixtures was carried out using the complete AChE-ICER-LC–MS platform. For efficient distinction of true actives from false positives, highly automated comparative analyses were run alternatingly using AChE-ICERs and negative control-ICERs, both online installed in the system. After washing unbound compounds to the waste, bound ligands were eluted from the AChE-ICER to a trapping loop using a denaturing solution. The trapped ligands were further separated and identified using LC–MS. Non-specific binding to the monolith support or non-functional sites of the immobilized enzyme was investigated by exposing analytes to the negative control-ICER. The specificity of the proposed approach was verified by analyzing a known AChE inhibitor in the presence of an inactive compound. The platform was applied to screen for AChE inhibitors in extracts of Corydalis yanhusuo. Eight compounds (columbamine, jatrorrhizine, coptisine, palmatine, berberine, dehydrocorydaline, tetrahydropalmatine and corydaline) with AChE binding affinity were detected and identified, and their AChE inhibitory activities were further verified by an in vitro enzymatic inhibition assay. Experimental results show that the proposed comparative online ligand fishing platform is suitable for rapid screening and mass-selective detection of AChE inhibitors in complex mixtures.

Characterization of E 471 food emulsifiers by high-performance thin-layer chromatography–fluorescence detection

Mono- and diacylglycerol (MAG and DAG) emulsifiers, also known as food additive E 471, are widely used to adjust techno-functional properties in various foods. Besides MAGs and DAGs, E 471 emulsifiers additionally comprise different amounts of triacylglycerols (TAGs) and free fatty acids (FFAs). MAGs, DAGs, TAGs and FFAs are generally determined by high-performance liquid chromatography (HPLC) or gas chromatography (GC) coupled to mass selective detection, analyzing the individual representatives of the lipid classes. In this work we present a rapid and sensitive method for the determination of MAGs, DAGs, TAGs and FFAs in E 471 emulsifiers by high-performance thin-layer chromatography with fluorescence detection (HPTLC–FLD), including a response factor system for quantitation. Samples were simply dissolved and diluted with t-butyl methyl ether before a two-fold development was performed on primuline pre-impregnated LiChrospher silica gel plates with diethyl ether and n-pentane/n-hexane/diethyl ether (52:20:28, v/v/v) as the mobile phases to 18 and 75 mm, respectively. For quantitation, the plate was scanned in the fluorescence mode at UV 366/>400 nm, when the cumulative signal for each lipid class was used. Calibration was done with 1,2-distearin and amounts of lipid classes were calculated with response factors and expressed as monostearin, distearin, tristearin and stearic acid. Limits of detection and quantitation were 1 and 4 ng/zone, respectively, for 1,2-distearin. Thus, the HPTLC–FLD approach represents a simple, rapid and convenient screening alternative to HPLC and GC analysis of the individual compounds. Visual detection additionally enables an easy characterization and the direct comparison of emulsifiers through the lipid class pattern, when utilized as a fingerprint.

BIOACTIVE FRACTION OF TROPIDIA CURCULIOIDES, A RARE ORCHID OF ARUNACHAL PRADESH, INDIA: PHYTOCHEMICAL PROFILE AND MARKER COMPOUNDS

Objective: Chemical profiling of the most active fraction of Tropidia curculioides, isolation and characterization of marker compounds along with the evaluation of biological activity. Methods: The most active Et2O fraction of roots of T. curculioides (TC) was analyzed by gas chromatography coupled with a mass selective detector. Repetitive chromatography followed by high-performance liquid chromatography of the active fraction afforded three major compounds. The structure of the compounds was established by nuclear magnetic resonance and mass spectral analysis. Antibacterial activity of the compounds was determined by agar well diffusion method against five multidrug-resistant (MDR) clinical isolates while minimum inhibitory concentration (MIC) and minimum bactericidal concentration were determined by microdilution method. Scanning electron microscopy was performed with compound 2 against Escherichia coli cells at MIC (15 μg/ml).Results: Analysis of the gas chromatography–mass spectrometry (GC–MS) spectra revealed that the isolated compounds constituted 27.16% of the total constituents. Two other chemical classes, namely, saturated fatty acids and sterol constituted 38.04% and 12.49%, respectively. The structure of the compounds was characterized as 4-hydroxy benzaldehyde (1), bisphenol F (2), and 3,5-dihydroxy-4-methoxybenzoic acid (3). The most significant bacteriostatic and bactericidal activity against E. coli comparable to that of tetracycline and gentamicin was observed with compound 2. Microscopic study confirmed that compound 2 affects integrity of cell membrane severely, causing death of the bacterium. Compound 1 and 3 showed moderate to good antibacterial activity against E. coli and Enterococcus sp. Cell cytotoxicity of the compounds was well within permissible limit. This is the first report of compounds in TC.Conclusion: The study identified three marker compounds from the less polar fraction of the roots of TC with significant antibacterial activity. The GC–MS spectra with marker compounds could be treated as the chemical fingerprinting of the bioactive fraction. The outcome justifies the use of the plant in traditional medicine.

Optimization of the method for the determination of diethyl sulfate at workplaces

Diethyl sulfate (DES) is a substance classified to the group of carcinogens. The value of maximum admissible concentration for this substance in workplace air is not specified in Poland. Due to the use of DES in domestic companies there is a need to develop a sensitive method for the determination of diethyl sulfate in the work environment. Studies were performed using gas chromatography (GC) technique. An Agilent Technologies chromatograph, series 7890A, with a mass selective detector (5975C, Agilent Technologies, USA) was used in the experiment. Separation was performed on a capillary column with Rtx-5MS (30 m × 0.25 mm × 0.25 μm) (Restek, USA). The possibility of using sorbent tubes filled with activated carbon (100 mg/50 mg), silica gel (100 mg/50 mg) and Porapak Q (150 mg/75 mg) for absorption of diethyl sulphate was investigated. The method of sampling air containing diethyl sulfate was developed. Among the sorbents to absorb DES Porapak Q was chosen. Determination of the adsorbed vapor includes desorption of DES, using dichloromethane/methanol mixture (95:5, v/v) and chromatographic analysis of so obtained solution. Method is linear (r = 0.999) within the investigated working range of 0.27- -5.42 μg/ml, which is an equivalent to air concentrations 0.0075-0.15 mg/m3 for a 36 l air sample. The analytical method described in this paper allows for selective determination of diethyl sulfate in the workplace air in the presence of dimethyl sulfate, ethanol, dichloromethane, triethylamine, 2-(diethylamino)ethanol, and triethylenetetramine. The method meets the criteria for performing procedures aimed at measuring chemical agents, listed in EN 482. Med Pr 2018;69(3):291-300.

Determination and pharmacokinetic study of guaiol in rat plasma by gas chromatography–mass spectrometry with selected ion monitoring

Guaiol has been used for thousands of years as a traditional Uygur medicine and is the primary active component found in Ferula ferulaeoides (Steud.) Korov (F. ferulaeoides). In our present study, a rapid, selective, and sensitive method of monitoring selected ions was established based on gas chromatography-mass spectrometry. This method was optimized for the quantification and pharmacokinetic analysis of guaiol in rat plasma following oral administration of chloroform extract from Ferula ferulaeoides. Plasma was extracted using liquid-liquid extraction with ethyl acetate and was analyzed on a HP-5MS column (30 m × 250 μm × 0.25 μm) with a mass selective detector. Detection was carried out under selected ion monitoring mode, and three selected ion monitoring ions (m/z 59.1, 107.1, and 161.1 for guaiol) were used for the quantitative determination of that under investigation. The assay demonstrated excellent linearity in the range of 1–200 ng/mL (r = 0.9993, n = 8) in the case of guaiol measured in rat plasma. The limit of detection and the limit of quantification for guaiol in rat plasma were found to be 0.25 ng/mL and 1 ng/mL, respectively. Intra-day and inter-day precisions were expressed as the relative standard deviation for the method and were in the range of 97.49%–106.16% and 97.04%–105.91%, respectively. Extraction efficiencies were all determined to be >90%, and recoveries were ranged from 91.25% to 96.24%. This method has been successfully applied for the pharmacokinetic evaluation of chloroform extract isolated from F. ferulaeoides following a single oral administration dose (157.5 mg/kg) in rats. The guaiol pharmacokinetic study demonstrated that the half-life of guaiol was 9.18 ± 3.75 h, the mean residence time was 9.07 ± 3.86 h, the maximum guaiol concentration in the plasma was 28.63 ± 6.82 ng/mL, and the maximum time guaiol was in the plasma was 0.50 h.

DETERMINATION OF 2,4-D IN SOME FOOD PRODUCTS (MILK, EGGS, LIVER, KIDNEYS) BY CHROMATOGRAPHY METHODS

The modern technique for the determination of 2,4-D, that belongs to global environmental pollutants, including the use of the technology of sample preparation - dispersive solid-phase-liquid extraction (QuEChERS), new for products of animal origin, has been developed. The sample preparation procedure includes the steps of: preliminary freezing of the sample to be analyzed, extraction with acetonitrile containing 1% acetic acid in the presence of MgSO4 and NaCl, purification by dispersive solid-phase extraction using a mixture of sorbents based on primarysecondary amine, octadecylsilane and graphitized carbon black, the freeze of the solution - at the last stage. Using the proposed technique allows to isolate the desired component from a matrix with a high content of animal fat into a selected organic solvent with high efficiency, that made it possible to expand significantly the arsenal of analytical equipment used to detect residual amounts of 2,4-D in food products of agricultural production, for example milk, eggs and offal (liver, kidney): tandem liquid mass-spectrometry (HPLC-MS/MS), gas-liquid chromatography with mass-selective and electron-capture detectors (GLC-MSD, GLC-ECD). The lower limit of the quantitative determination is 2,4-D: 0,005 mg/kg for milk and eggs, 0.05 mg/kg for the liver and kidneys. Completeness of extraction is 85-94%, RMS of repeatability is 3,4-11,4%.

RESEARCH OF THE BIOMARKER OF THE EXPOSURE TO ORGANOCHLORINE COMPOUNDS IN EMPLOYEES OF THE VINYL CHLORIDE AND POLYVINYL CHLORIDE MANUFACTURE

This article presents results of the quantitative assessment of the blood content of organochlorine compounds (vinyl chloride, 1,2-dichloroethane) and its metabolite thiodiacetic acid (TDAA) in the urine of workers of the production of vinyl chloride (VC) and polyvinyl chloride(PVC). The studies were executed in two phases: in the first phase, 65 persons were surveyed at the time of the periodic medical examination, at the second phase - 10 workers of basic professions (apparatchiks of gas separation and polymerization and cleaners) werу observed in the dynamics of 12-hour shifts. The sample consisted of persons, who regularly passed bioassay test before the work shift, and after the shift and the next day before the shift. The purpose of the study was the evaluation of the content of chlorinated hydrocarbons in the organism of workers of VC and PVC productions. The studies were conducted using the methods developed in our laboratory with using a gas chromatograph Agilent 7890A with a flame ionization detector, docked with the Headspace Sampler Agilent 7694E and gas chromatograph Agilent 7890A with a Mass Selective Detector Agilent 5975C. Statistically significant differences in TDAA urine content were found between workers and cases from the control group. There was detected its dependence on the levels of as well exposure to toxic substances, the production, and occupation, as the duration of the post-exposure period. The average value of the urine content of TDAA in workers of the workshop of VC production authentically was shown to be 2.57 times higher than in workers of the workshop of the PVC production. The average urine concentration of TDAA in workers of both workshops were 5.0 and 19.9 times higher than in cases from the control group (0.27±0.02 mg/dm3). Th urine TDAA content in panmen was authentically 2 times higher than in workers from the group of the subsidiary occupations. It should be noted that the largest percentage of urine samples with exceeding TDAA levels in the control group - 84.8% was observed in panmen, in the group of auxiliary occupation the percentage of these samples amounted to 75.0%. Increased levels of the urinary TDAA excretion was observed during the work after 12 hours after the end of the shift, before starting the next shift period and during a medical examination 24 hours after the cessation of the exposure to toxicants, which may be the optimal time urine collection during biomonitoring studies.

Profiles of polycyclic aromatic hydrocarbons in smoke from combustion and thermal decomposition of poplar wood pellets and sawdust

The aim of this paper is to determine the level and distribution of the sixteen polycyclic aromatic hydrocarbons (PAHs) listed by the US Environmental Protection Agency (US-EPA) in smoke from poplar wood pellets and sawdust combustion and thermal decomposition, respectively. Namely, the growth of selected poplar plantations, wood cultivation and production in the north part of the Republic of Serbia, Vojvodina Province, considerably increased. However, mechanical wood processing creates a lot of sawdust, which causes an occupational and environmental risk and also poses a fire hazard. Furthermore, in order to protect the environment and provide additional energy sources, sawdust is commonly pelletized and further used as a fuel. Thus, the assessment of environmental impact of its use becomes an important issue. Therefore, the intention of the authors was to determine the level and profile of PAHs emitted by combustion and thermal decomposition under atmospheric conditions of poplar wood pellets and sawdust. The 16 US-EPA PAHs were analyzed by gas chromatograph with mass selective detector. The level of total US-EPA 16 PAHs formed during combustion of wood pellets was 4.7mgkg−1, whereas during the sawdust combustion it was 3.8mgkg−1, while the resulting total PAHs concentration during thermal degradation under atmospheric conditions of pellets and sawdust was 3.4mgkg−1 and 3.7mgkg−1, respectively. The most common PAHs present in smoke from the combustion and thermal decomposition under atmospheric conditions of poplar wood pellets were phenanthrene, fluorene and naphthalene, while from the sawdust were phenanthrene, naphthalene, acenaphthylene and fluorene, respectively. BaPeq value obtained during the combustion of wood pellets was 0.081mg kg−1, whereas from the combustion of sawdust it was 0.047mgkg−1, while the resulting BaPeq value during the thermal degradation under atmospheric conditions of pellets and sawdust was 0.057mgkg−1 and 0.049mgkg−1, respectively. Biomass densification process did not affect PAHs emission neither during the combustion process nor the thermal decomposition process. To the best of our knowledge, it is the first study which considers the level and profile of PAHs found in smoke from the combustion and thermal decomposition of poplar clone I-214 (P. x euramericana cl. I-214) cultivated in the Republic of Serbia.