Gas Chromatographic Mass Spectrometric Determination Research Articles

Chemical Composition of the Essential Oils and Volatiles of Salvia leriifolia by Three Different Extraction Methods Prior to Gas Chromatographic-Mass Spectrometric Determination: Comparison of HD with SFME and HS-SPME

The essential oils and volatiles from the aerial parts of Salvia leriifolia obtained by hydrodistillation (HD), solvent-free microwave extraction (SFME) and headspace solid-phase microextraction (HS-SPME) approaches were analyzed using the GC and GC-MS instrumentations. Using the HD, SFME and HS-SPME methods, we were able to recognize thirty five, twenty seven and thirty seven components covering 95.30%, 98.35% and 93.32% of the oil compositions and volatile fractions, respectively. In the oil obtained by the HD method, β-pinene (13.88%), 1,8-cineole (13.74%), α-pinene (10.40%), α-cadinol (10.00%) and αbisabolol (7.35%) were the most abundant components whereas in the oil separated by the SFME approach, 1,8-cineole (24.13%), α-pinene (18.08%), β-pinene (11.91%), borneol (6.27%), α-cadinol (5.57%) and δcadinene (5.08%) were the major compounds. Also, in the volatile compounds isolated by the HS-SPME method, β-pinene (13.89%), 1,8-cineole (10.39%), α-pinene (8.74%) and δ-cadinene (8.25%) were the main fractions.

Profiling Volatile Natural Compounds from Flowers, Leaves and Stems of Marrubium anisodon Using Headspace Solid Phase Microextraction in Combination with Gas Chromatographic Mass Spectrometric Determination

The present study describes the potential capabilities of an efficient extraction technique, namely headspace solid-phase microextraction (HS-SPME) to isolate the volatile fractions from the flowers, leaves and stems of Marrubium anisodon in combination with the analysis by GC and GC-MS. By means of the HS-SPME method, 24, 16 and 24 components were characterized in the corresponding profiles, representing 89.6%, 97.4% and 93.6% of the total compositions, respectively. Limonene was the most abundant natural compound in all the volatile profiles. It was also observed that in all of the volatiles, monoterpene hydrocarbons constituted the main components while the next most common group was due to sesquiterpene hydrocarbons for volatile parts of flowers and leaves. However, in that of stems, oxygenated monoterpenes had the second rank from frequency point of view.

GC-MS Determination of Bioactive Compounds and Nutrient Composition of Myristica fragrans Seeds

ABSTRACTThe chemical constituents in Myristica fragrans seeds were analyzed using proximate analysis, atomic absorption spectroscopic (AAS), phytochemical and gas chromatographic-mass spectrometric (GC-MS) methods. Results showed the percentage proximate composition of M. fragrans seeds as: crude ash < crude protein < crude fibre < moisture < crude fat < nitrogen free extract. The AAS analysis indicated the presence of magnesium (133.10mg kg–1), sodium (423.55 mg kg–1), calcium (1560.09 mg kg–1) and potassium (5139 mg kg–1). The aqueous extract of M. fragrans seeds had higher concentrations of phenols (0.10 mg gallic acid equivalent (GAE) g–1) and flavonoids (1.10 mg quercetin equivalent (QE) g–1) than the dichloromethane extracts that had phenols (0.03 mg GAE g–1) and flavonoids (0.10 QE mg g–1). The aqueous and dichloromethane extracts contained 6 and 18 bioactive compounds respectively.

QuEChERS Method Followed by Solid Phase Extraction Method for Gas Chromatographic-Mass Spectrometric Determination of Polycyclic Aromatic Hydrocarbons in Fish.

A gas chromatography equipped with mass spectrometer (GCMS) method was developed and validated for determination of 16 polycyclic aromatic hydrocarbons (PAHs) in fish using modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) method for extraction and solid phase extraction for sample cleanup to remove most of the coextract combined with GCMS for determination of low concentration of selected group of PAHs in homogenized fish samples. PAHs were separated on a GCMS with HP-5ms Ultra Inert GC Column (30 m, 0.25 mm, and 0.25 µm). Mean recovery ranged from 56 to 115%. The extraction efficiency was consistent over the entire range where indeno(1,2,3-cd)pyrene and benzo(g,h,i)perylene showed recovery (65, 69%), respectively, at 2 µg/kg. No significant dispersion of results was observed for the other remaining PAHs and recovery did not differ substantially, and at the lowest and the highest concentrations mean recovery and RSD% showed that most of PAHs were between 70% and 120% with RSD less than 10%. The measurement uncertainty is expressed as expanded uncertainty and in terms of relative standard deviation (at 95% confidence level) is ±12%. This method is suitable for laboratories engaged daily in routine analysis of a large number of samples.

Capsaicinoids, Tocopherol, and Sterols Content in Chili (Capsicum sp.) by Gas Chromatographic-Mass Spectrometric Determination

A gas chromatography-mass spectrometry method was developed for the quantitative determination of capsaicinoids, vitamin E, and phytosterols in chili peppers using a simple extraction technique for rapid screening. These components were extracted with acetonitrile and were injected into gas chromatography attached with mass spectrometry. The mean recovery values for triplicate analysis were between 90.6–99.7%. Besides major capsaicinoids (capsaicin, dihydrocapsaicin, nordihydrocapsaicin), four more minor capsaicinoids (nonivamide, nornordihydrocapsaicin, homodihydrocapsaicin I and II) were detected in chili samples. α-Tocopherol was also detected in the same run along with three phytosterols (campesterol, γ-sitosterol, and stigmasterol). Variations were observed across the chili sample in all of the constituents except a few minor capsaicinoids. The method was suitable for simultaneous estimation of capsaicinoids, vitamin E, and phytosterols in a single run from any types of pepper. Thus, the method is effective for rapid screening of peppers for its nutraceutical composition using single solvent extraction.

Chemical Composition of the Volatile Oils from the Aerial Parts of Artemisiaannua L. (Asteraceae) by Using Head Space Solid Phase Microextractionand Hydrodistillation Methods Prior to Gas Chromatographic-MassSpectrometric Determination: A Comparative Investigation

The present report deals with the analysis, comparison of content and composition of the volatiles obtained by hydrodistillation (HD) and head space-solid phase microextraction (HS-PME) procedures from the fresh aerial parts of Artemisia annua L. The SPME headspace volatiles were collected using a 100 μm polydimethylsiloxane (PDMS) fiber. The composition of the volatile essential oils were investigated by GC-FID and GC-MS. Two series of natural compounds were identified constituting 94.6 and 95.18 % of the oils for HD and HS-SPME methods. In the water distilled oil, camphor (16.30 %), β-selinene (10.41 %), artemisia ketone (8.79 %), germacrene-D (7.14 %), α-pinene (4.79 %), 1,8-cineol (4.38 %) and α-selinene (4.09 %) were found to be major components. Moreover, the oil extracted by HS-SPME technique was mainly composed of α-pinene (12.03 %), artemisia ketone (11.24 %), β-selinene (8.73 %), 1,8-cineol (6.76 %), camphene (4.90 %) and α-selinene (4.85 %) as the most abundant fractions. Results imply that the use of HS-SPME could somewhat affect the composition of the essential oils

Rapid micropreparation procedure for the gas chromatographic–mass spectrometric determination of BHT, BHA and TBHQ in edible oils

A rapid, accurate and organic solvent saving procedure has been developed for the GC/MS determination of three phenolic antioxidants butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA) and butyl hydroquinone (TBHQ) in vegetable oils. The method involves two-step microextraction and a centrifugal procedure in a 2 mL autosampler vial, consuming only 50 mg sample and total 1 mL acetonitrile. Recoveries of the phenolic antioxidants when spiked to soya bean oil, peanut oil and cereal cooking oil at 50, 200 and 250 mg/kg, respectively were in the ranges 95.6–104.3% for BHT, 99.7–107.5% for BHA and 93.6–103.8% for TBHQ with the relative standard deviation (RSD) were less than 3% for their independent measurements. The developed method was repeatable and could be applied to determine trace amounts of phenolic antioxidants in vegetable oils.

Automatic heating and cooling system in a gas purge microsyringe extraction

The gas purge microsyringe extraction (GP-MSE) technique offers quantitative and simultaneous extraction, and rapid gas chromatographic–mass spectrometric determination of volatile and semivolatile chemicals is possible. To simplify the application, a new automatic temperature control system was developed here. Stable heating and cooling over a wide range of temperatures were achieved using a micro-heater and thermoelectric cooler under varying gas flow conditions. Temperatures could be accurately controlled in the range 20–350°C (heating) and 20 to −4°C (cooling). Temperature effects on the extraction performance of the GP-MSE were experimentally investigated by comparing the recoveries of polycyclic aromatic hydrocarbons (PAHs) under various experimental conditions. A sample treatment was completed within 3min, which is much less than the time required for chromatographic analysis. The recovery of chemicals determined ranged from 81 to 96%. High reproducibility data (RSD≤5%) were obtained for direct extraction of various analytes in spiked complex plant and biological samples. The data show that the heating and cooling system has potential applications in GP-MSE system for the direct determination of various kinds of volatile and semivolatile chemicals from complex matrices without any, or only minor, sample pretreatment.

Plunger-in-needle solid-phase microextraction with graphene-based sol–gel coating as sorbent for determination of polybrominated diphenyl ethers

A solid-phase microextraction (SPME) device, assembled with a commercially available plunger-in-needle microsyringe, with the plunger coated with graphene via a sol–gel approach, was developed for the gas chromatographic–mass spectrometric determination of polybrominated diphenyl ethers (PBDEs) in environmental samples. This is the first application of graphene-based sol–gel coating as SPME sorbent. Parameters affecting the extraction efficiency were investigated in detail. The new coating exhibited enrichment factors for PBDEs between 1378 and 2859. The unique planar structure of graphene enhanced the π–π interaction with the aromatic PBDEs; additionally, the sol–gel coating technique created a porous three-dimensional network structure which offered larger surface area for extraction. The stainless steel plunger provided firm support for the coating and enhanced the durability of the assembly. The plunger-in-needle microsyringe represents a ready-made tool for SPME implementation. Under the optimized conditions, the method detection limits for five PBDEs were in the range of 0.2 and 5.3 ng/L (at a signal/noise ratio of 3) and the precision (% relative standard deviation, n = 5) was 3.2–5.0% at a concentration level of 100 ng/L. The linearities were 5–1000 or 10–1000 ng/L for different PBDEs. Finally, the proposed method was successfully applied to the extraction and determination by gas chromatography–mass spectrometry of PBDEs in canal water samples.

Toxicokinetics of tabun enantiomers in anaesthetized swine after intravenous tabun administration

In the present study, we report the first in vivo toxicokinetic study of tabun (O-ethyl-N,N-dimethylphosphoramidocyanidate). The toxicokinetics of the enantiomers of tabun were investigated in anesthetized swine after intravenous administration of 3 × LD 50 (161.4 μg/kg) tabun. Blood samples were taken for gas chromatographic–mass spectrometric determination of the tabun enantiomers and for measurement of the activity of red blood cell acetylcholinesterase (AChE) and plasma butyrylcholinesterase (BChE). The tabun enantiomers could be quantified in swine blood to a minimum concentration of 3.0 pg/ml (18.5 pM) and could be detected to a minimum concentration of 1.0 pg/ml (6.2 pM). The concentration–time profiles of both tabun enantiomers were best described by a bi-exponential equation. The elimination of (+)-tabun and (−)-tabun were comparable in the initial phase. In the terminal phase a remarkable difference was found, with terminal half lives of 11.5 min for (+)-tabun and 23.1 min for (−)-tabun. (+)-Tabun showed a markedly longer persistence in vivo than (+)-enantiomers of other G-type nerve agents and could be detected in all swine at least up to 30 min post-injection, (−)-tabun at least up to 90 min post-injection. These results demonstrate a rather rapid elimination of tabun enantiomers in vivo and may provide a toxicokinetic basis for the further development and optimization of medical countermeasures against this nerve agent.

Dispersive Liquid−Liquid Microextraction Coupled with Dispersive μ-Solid-Phase Extraction for the Fast Determination of Polycyclic Aromatic Hydrocarbons in Environmental Water Samples

A new two-step microextraction technique, combining dispersive liquid-liquid microextraction (DLLME) and dispersive microsolid-phase extraction (D-micro-SPE), was developed for the fast gas chromatographic-mass spectrometric determination of polycyclic aromatic hydrocarbons (PAHs) in environmental samples. A feature of the new procedure lies in that any organic solvent immiscible with water can be used as extractant in DLLME. A special apparatus, such as conical-bottom test tubes, and tedious procedures of centrifugation, refrigeration of the solvent, and then thawing it, associated with classical DLLME or similar techniques are not necessary in the new procedure, which potentially lends itself to possible automation. In the present D-micro-SPE approach, hydrophobic magnetic nanoparticles were used to retrieve the extractant of 1-octanol in the DLLME step. It is noteworthy that the target of D-micro-SPE was the 1-octanol rather than the PAHs. Because of the rapid mass transfer associated with the DLLME and the D-micro-SPE steps, fast extraction could be achieved. Parameters affecting the extraction efficiency were investigated in detail. The optimal conditions were as follows: vortex at 3200 rpm in the DLLME step for 2 min and in D-micro-SPE for 1 min and then desorption by sonication for 4 min with acetonitrile as the solvent. The results demonstrated that enrichment factors ranging from 110- to 186-fold were obtained for the analytes. The limits of detection and the limits of quantification were in the range of 11.7-61.4 pg/mL and 0.04-0.21 ng/mL, respectively. The linearities were 0.5-50, 1-50, or 2-50 ng/mL for different PAHs. Finally, the two-step extraction method was successfully used for the fast determination of PAHs in river water samples. This two-step method, combining two different and efficient miniaturized techniques, provides a fast means of sample pretreatment for environmental water samples.

Cholinesterase-inhibiting Potentials of Amberlite XAD-2 Resin Extracts Collected from River and Drinking Waters in Northwest District of Chiba Prefecture, Japan

Amberlite XAD-2 resin extracts of river and drinking water sampled in each month during the period from January to December 2008 from the Northwest district of Chiba Prefecture were investigated to characterize and determine their cholinesterase (ChE)-inhibiting potentials and pesticide levels. The XAD-2 extracts from river water collected during the mid-spring to mid-summer periods exhibited strong inhibition effect to horse serum ChE, reflecting the application of organophosphorus and carbamate pesticides to paddy fields. Gas chromatographicmass spectrometric (GC/MS) determinations of the XAD-2 extracts of the river water collected during spring to summer periods also showed to be comparatively high levels of agricultural chemicals, such as herbicides, insecticides and fungicides, as compared with those detected in the drinking water. Although a considerable reduction in the ChE-inhibiting potentials and in the GC/MS detectable compound levels was observed for the river water samples, it is particularly interest that ChE-inhibiting potentials still remained in the drinking water.

Comparison of isolation methods for the determination of buckwheat volatile compounds

Five different isolation techniques were combined with gas chromatographic–mass spectrometric determination of aroma compounds from buckwheat: dynamic headspace (DHS) with cryotrapping or sorbent trapping, solid-phase microextraction (SPME), headspace sorptive extraction (HSSE), solvent extraction (SE) and simultaneous distillation–extraction (SDE). Optimisation of each technique is presented, as well as comparison of the chemical profiles obtained by them. Solvent extraction with methanol resulted in the isolation of rather polar and less volatile compounds and was deemed least suitable for the odour-active compounds. Only SPME with DVB/CAR/PDMS fibre was suitable for the isolation of highly volatile compounds in a wider polarity range. DHS extracted the smallest number of compounds, but with the comparable chemical profile as obtained by SDE, which was chosen as the most suitable technique to obtain the aroma compounds of cooked buckwheat. The applied isolation techniques are complementary in their ability to extract a representative aroma profile of buckwheat.

Chromatographic determination of 6-substituted 2-thiouracyls, thyreostatic preparations

Optimum conditions (borate buffer solution pH 9.18, voltage 20 kV) were selected for the separation and quantitative determination of antithyroid preparations, 6-R-2-thiouracyls, where R = H (TU), CH3 (MTU), n-C3H7 (PTU) by capillary zone electrophoresis in a quartz capillary 60 cm (effective length of 50 cm) × 75 μm. The procedure allows for the estimation of the concentration of substances in the ranges 1.3–103, 1.4–114, and 1.7–136 μg/mL, respectively, with detection limits of 0.93, 0.73, and 0.86 μg/mL for TU, MTU, and PTU, respectively. The procedure of the gas chromatographic-mass spectrometric determination of PTU with an analytical range of 10–50 μg/mL and a detection limit of 5.22 μg/mL is developed.

New application of mixed C18-SCX SPE clean-up in gas chromatographic-mass spectrometric determination of six β2-agonist residues in pig's liver

Summary A new mixed C18-SCX SPE column and gas chromatography-mass spectrometry have been used for determination of six β2-agonists residues in pig's liver. After hydrolysis, the six β2-agonists were extracted with 6:4 (v/v) ethyl acetate-isopropanol and then cleaned on a commercial mixed-adsorbent solid-phase extraction column. The eluted solution was analyzed by gas chromatography-mass spectrometry (GC-MS) and quantified by the external standard method. Sample pre-treatment and GC-MS conditions were critically examined. The linear range was 0.005–2.00 mg L–1 and correlation coefficients were 0.9987–1.000. The LOD of mabuterol, clenbuteroland, and salbutamol was 0.2 μg kg–1. Average recoveries of these three compounds from spiked pig's liver ranged from 65.3 to 95.8% and relative standard deviations were between 5.4 and 9.9%. The LOD of cimaterol, bromobuterol, and ractopamine was 0.3 μg kg–1. Average recoveries of these three compounds from spiked pig's liver ranged from 63.8 to 88.1% and relative standard deviations were between 5.0 and 9.7%. These results indicate the method is highly sensitive, simple, inexpensive, and results in good purification. It could also meet requirements for analysis of pig's urine in domestic and import/export inspection work.

Simple one-step extraction and cleanup by pressurized liquid extraction for gas chromatographic–mass spectrometric determination of pesticides in green leafy vegetables

A simple one-step extraction and cleanup using a pressurized liquid extraction method was developed for the gas chromatographic–mass spectrometric determination of pesticides in vegetables. The pressurized liquid extraction conditions were optimized and cleanup agents were evaluated. The investigated pesticides included six insecticides, chlorpyrifos methyl, pirimiphos-methyl, malathion, chlorpyrifos, O-ethyl O-4-nitrophenylphenyl phosphonothioate (EPN) and permethrins, a fungicide, isoprothiolane, and a herbicides, thiobencarb. The cleanup agent and a mixture of the vegetable and anhydrous sodium sulfate were separately packed in an extraction vessel. A transparent and colorless extract was obtained using graphitized carbon as the cleanup agent. The overall recoveries were 71–103% and the relative standard deviations ranged from 5.6 to 24%. The limit of detection values were 3–8 μg kg −1. This method was successfully applied to green leafy vegetables.

Improved cleanup technique for gas chromatographic–mass spectrometric determination of alkylphenols from biota extract

A simple and economical cleanup technique was developed to determine alkylphenols by GC–MS from biological extracts containing relatively high lipids. The lipids were successfully removed from bivalve extracts through a two-step cleanup. The new method is a combination of Florisil adsorption chromatography and silyl derivatization technique. Low and high (non-polar and highly polar) molecular weight lipids were removed from the biota extract with deactivated Florisil column in the first step. And in the second step, middle molecular weight (middle polar) lipids were removed in an activated Florisil column after the alkylphenols were converted to corresponding silyl derivatives with bis(trimethylsilyl)trifluoroacetamide (BSTFA). On the basis of the above results, a simple cleanup kit was developed for convenience. The technique was optimized with reference to the activity of packing materials and polarity of eluting solvents. Only 3 g of Florisil, 25 mL of hexane and 10 mL of dichloromethane were required for one sample. The recoveries of alkylphenols from spiked samples varied from 88 to 103% with a low relative standard deviation (mean value: 5.3%) and the recovery was similar or even higher than other methods currently in use. The technique was successfully applied to mussel samples from Masan Bay, South Korea. Simultaneous measurement of these compounds in water, sediment and biota; the resulting bio-concentration factor and their relationships confirm previously published works, validating the method applied.

Gas chromatographic–mass spectrometric determination of alkylphosphonic acids from aqueous samples by ion-pair solid-phase extraction on activated charcoal and methylation

In the present paper, we report an improved ion-pair solid-phase extraction (IP-SPE) method for the analysis of alkylphosphonic acids, namely, methyl, ethyl and propylphosphonic acids, present in the aqueous sample. The aqueous sample was mixed with an ion-pair reagent, phenyltrimethylammonium hydroxide (PTMAH) and passed through activated charcoal SPE cartridge. The retained chemicals in the cartridge were extracted with methanol and analysed by gas chromatography–mass spectrometry (GC–MS) under the electron impact ionization (EI) mode. The analytes were converted to their methyl esters by pyrolytic methylation in the hot GC injection port. The recoveries of alkylphosphonic acids were above 95% and the minimum detection limits were as low as 10 ng/mL. The recovery of the test chemicals was tested with solvents, dichloromethane, n-hexane, ethyl acetate, acetone, acetonitrile and methanol. The chemicals could be efficiently extracted by the hydrophilic solvents. The method did not work at the highly acidic pH (when acidified with dilute HCl) but worked well from pH 4.0 to 14.0. The present method was also tested with other tetra-(methyl, ethyl, propyl and n-butyl)ammonium hydroxides. The test chemicals were not converted to their methyl and ethyl esters with tetramethyl and tetraethylammonium hydroxides, whereas they were converted to their corresponding propyl and n-butyl esters with tetrapropyl and tetra( n-butyl)ammonium hydroxides. The method was also applied to two highly cross-linked polymeric sorbents DSC-6S and Oasis HLB. The recovery of the chemicals on these sorbents was observed to be poor. Methylation using phenyltrimethylammonium hydroxide is non-hazardous and advantageous over methylation using diazomethane. The method was applied to the analysis of aqueous samples given in one of the official proficiency tests conducted by the Organization for the Prohibition of Chemical Weapons and all the spiked chemicals were identified as methyl esters.

Solid-Phase Extraction and Gas Chromatographic-Mass Spectrometric Determination of the Veterinary Drug Xylazine in Human Blood

This paper presents a method for the determination of xylazine in whole blood using solid-phase extraction and gas chromatography-mass spectrometry. This technique required only 0.5 mL of sample, and protriptyline was used as internal standard (IS). Limits of detection and quantitation (LOQ) were 2 and 10 ng/mL, respectively. The method was found to be linear between the LOQ and 3.50 microg/mL, with correlation coefficients higher than 0.9922. Precision (intra- and interday) and accuracy were in conformity with the criteria normally accepted in bioanalytical method validation. The analyte was stable in the matrix for at least 18 h at room temperature and for at least three freeze/thaw cycles. Mean recovery, calculated at three concentration levels, was 87%. To the best of our knowledge, this is the first time that solid-phase extraction is used as sample preparation technique for the determination of this compound in biological media. Because of its simplicity and speed when compared to other extraction techniques, the herein described method can be successfully applied in the diagnosis of intoxications by xylazine.

Continuous-flow microextraction and gas chromatographic–mass spectrometric determination of polycyclic aromatic hydrocarbon compounds in water

A new method of the determination polycyclic aromatic hydrocarbons (PAHs) in water samples was developed by continuous-flow microextraction (CFME) coupled with gas chromatography–mass spectrometry (GC–MS). In this experiment, 15 mL sample solution with no salt-added was flowed at the rate of 1.0 mL min −1 through 3 μL benzene as extraction solvent. Under the optimal extraction conditions, the developed method was found to yield a linear calibration curve in the concentration range from 0.05 to 15 ng mL −1. Furthermore, the accuracy and repeatability of the method were good by calculating from water samples spiked at known concentrations of PAHs, and the recovery of optimal method was satisfactory. The results showed that CFME was an efficient preconcentration method for extraction of PAHs from spiked water samples.