Fast Gas Chromatography Research Articles

Yields of Mine Fuel under the Heat Effect of Fire Flame when Methane Explosions

Abstract In order to study the mechanism of second-fire induced by methane explosions, the yields of several main fuels in mine were studied through doing some fast pyrolysis experiments. Use courier point fast pyrolysis system and GC to do this experiment. All experiment conditions fulfill methane explosions environment thoroughly. The experiment results show that the yields mainly include CH4, C2H4, C2H6, C3H6, C3H8, C4, C5, CO, CO2 etc. Where, CH4, C2H4, C3H6, C4, C5, CO, CO2 yields are larger than others. Only supporting wood has H2, and only PVC has HCl but others. And include some dangerous flammable gas such as CH4, CO, H2 etc. The model and influence factors show that temperature and heating rate have great influence on yields but pressure, especially temperature. All results show that methane explosions could produce some flammable gas which out of fuel, and could induce second fire.

Determination of polychlorinated biphenyls by fast chromatography mass-spectrometry in environmental and biological samples

A method for the determination of polychlorinated biphenyls (PCB) by fast gas chromatography coupled with mass-spectrometric detection in selective ion monitoring mode has been developed. Chromatographic separation was carried out with HT-8 column (30 m × 0.25 mm) under sharp temperature increase from 80 to 320°C at a rate of 40°C/min. Duration of chromatography is 10 min. Fast chromatography conditions suggested by authors makes it possible to increase S/N ratios 10 times and so to reduce significantly the representative weight of the sample and develop an effective sample preparation technique. The method was used for PCB determination in Baikal area samples such as soil, snow, sediments from Lake Baikal and its tributaries, tissues of Baikal omul (Coregonus migratorius, Georgi, 1775) and blubber of Baikal seal (Phoca sibirica Gm.). The sample preparation stage includes PCB extraction from environmental samples and hydrolyzate of biological material with the following cleanup of the extract on the compact silica gel and florisil cartridges (0.5 g of the sorbent). The method enables the measurements of total PCBs and isomer groups of the same chlorination level with interlaboratory precision of no greater than 10% and the determination of indicator congeners (PCBs 28, 52, 101, 118, 138, 153, and 180) with a precision not exceeding 15%.

A low thermal mass fast gas chromatograph and its implementation in fast gas chromatography mass spectrometry with supersonic molecular beams

A new type of low thermal mass (LTM) fast gas chromatograph (GC) was designed and operated in combination with gas chromatography mass spectrometry (GC-MS) with supersonic molecular beams (SMB), including GC-MS-MS with SMB, thereby providing a novel combination with unique capabilities. The LTM fast GC is based on a short capillary column inserted inside a stainless steel tube that is resistively heated. It is located and mounted outside the standard GC oven on its available top detector port, while the capillary column is connected as usual to the standard GC injector and supersonic molecular beam interface transfer line. This new type of fast GC-MS with SMB enables less than 1 min full range temperature programming and cooling down analysis cycle time. The operation of the fast GC-MS with SMB was explored and 1 min full analysis cycle time of a mixture of 16 hydrocarbons in the C(10)H(22) up to C(44)H(90) range was achieved. The use of 35 mL/min high column flow rate enabled the elution of C(44)H(90) in less than 45 s while the SMB interface enabled splitless acceptance of this high flow rate and the provision of dominant molecular ions. A novel compound 9-benzylazidanthracene was analyzed for its purity and a synthetic chemistry process was monitored for the optimization of the chemical reaction yield. Biodiesel was analyzed in jet fuel (by both GC-MS and GC-MS-MS) in under 1 min as 5 ppm fatty acid methyl esters. Authentic iprodion and cypermethrin pesticides were analyzed in grapes extract in both full scan mode and fast GC-MS-MS mode in under 1 min cycle time and explosive mixture including TATP, TNT and RDX was analyzed in under 1 min combined with exhibiting dominant molecular ion for TATP. Fast GC-MS with SMB is based on trading GC separation for speed of analysis while enhancing the separation power of the MS via the enhancement of the molecular ion in the electron ionization of cold molecules in the SMB. This paper further discusses several features of fast GC and fast GC-MS and the various trade-offs involved in having powerful and practical fast GC-MS.

Fast headspace-enantioselective GC–mass spectrometric-multivariate statistical method for routine authentication of flavoured fruit foods

This study describes a rapid total analysis system (TAS) to detect the authenticity of fruit-flavoured foods and beverages by on-line combining headspace solid phase microextraction (HS-SPME) with enantioselective GC–MS (Es-GC–MS) and statistical multivariate methods (PCA, HCA). Peach, coconut, apricot, raspberry, as fruits mainly characterised by γ- and δ-lactones as chiral markers, strawberry (α-ionone, linalool, nerolidol, ethyl 2-methylbutyrate, 2-methylbutyric acid and γ-lactones) and melon (ethyl 2-methylbutyrate and 2-methylbutanol) were investigated. The system was developed by (a) optimising non-equilibrium HS-SPME sample preparation, (b) speeding-up ES-GC using cyclodextrin derivatives as chiral selectors with conventional and narrow-bore columns and (c) elaborating data by multivariate methods. The resulting TAS affords a reduction of the time needed for the whole analytical process from about 150min to 20–50min (67–87% of the current routine method) depending on matrix, sampling and analysis conditions and Es-GC columns.

Rapid simultaneous determination of multiple pesticide residues in traditional Chinese medicines using programmed temperature vaporizer injection-fast gas chromatography coupled with mass spectrometry

A fast gas chromatography coupled with mass spectrometry (GC-MS) using large volume injection with programmed temperature vaporizer in solvent vent mode (PTV-LVI-SV) was developed for the trace determination of multiple pesticide residues in traditional Chinese medicines (TCMs). Experimental conditions of PTV-LVI-SV injection were optimized by central composite design. The optimized result was that initial temperature was held at 40°C for 39 s, vent flow rate was set at 45 mL/min and vent pressure was held at 0 psi for 36 s, injection volume was 10 μL. Furthermore, the quick and effective QuEChERS (quick, easy, cheap, effective, rugged and safe) method was performed to extract and purify pesticide residues in TCMs. The prepared samples were analyzed with GC-MS in the selected ion monitoring mode (SIM). The lowest LOD was 4 μg/kg for some pesticides. The recoveries were checked by spiking samples with pesticides at 25, 50 and 250 μg/kg. The average recoveries of most pesticides were from 80 to 118%. The result indicated that QuEChERS and PTV-LVI-SV GC-MS method was a rapid and sensitive analysis technique for the determination of multiple pesticide residues in TCMs.

Development, Validation, and Application of a Fast and Simple GC–MS Method for Determination of Some Therapeutic Drugs Relevant in Emergency Toxicology

To date, immunoassays are commercially available for quantification of valproic acid, salicylic acid, paracetamol, phenobarbital, phenytoin, and primidone. As they are no longer available, a fast, simple, and cost-effective quantitative gas chromatography-mass spectrometry (GC-MS) method was developed and fully validated for these drugs. After simple and fast liquid-liquid extraction, the samples were analyzed by GC-MS using the selected ion monitoring mode. The method was validated including the parameters selectivity, calibration model, precision, accuracy, and extraction efficiency. The above-mentioned analytes were separated within 8.5 minutes and sensitively detected. No interfering peaks were observed in blank samples from 8 different sources. The linearity ranges were 20-200 mg/L for valproic acid, 100-1200 mg/L for salicylic acid, 10-200 mg/L for paracetamol, 10-200 mg/L for phenobarbital, 4-20 mg/L for primidone, and 2.5-30 mg/L for phenytoin. Generally accepted criteria for accuracy and precision were fulfilled for all analytes using 6-point calibration. Even 1-point calibration was applicable for all analytes. The assay was successfully applied to analysis of real plasma samples and proficiency testing material. The assay described allowed fast and reliable determination of analytes relevant in the diagnosis of poisonings. Furthermore, time- and cost-saving 1-point calibration was shown to be suitable for daily routine work, especially in emergency cases.

Multiclass determination of 66 organic micropollutants in environmental water samples by fast gas chromatography–mass spectrometry

A multiresidue method has been developed for quantification and identification of 66 multiclass priority organic pollutants in water by fast gas chromatography (GC) coupled to mass spectrometry (MS). Capabilities and limitations of single quadrupole mass spectrometer as detector in fast GC were studied evaluating the chromatographic responses in terms of sensitivity and chromatographic peak shapes, as they were influenced by scan time. The number of monitored ions in a selected ion monitoring (SIM) group strongly conditioned the scan time and subsequently the number of data points per peak. A compromise between peak shape and scan time was adopted in order to reach the proper conditions for quantitative analysis. An average of 10-15 points per peak was attained for most compounds, involving scan times between 0.1 and 0.22 s. The method was validated for mineral, surface, and groundwater. A solid-phase extraction pre-concentration step using C(18) cartridges was applied. Four isotopically labeled standards were added to the samples before extraction and used as surrogates to ensure a reliable quantification. Analyses were performed by GC-MS in electron ionization mode, monitoring the three most abundant and/or specific ions for each compound and using the intensity ratios as a confirmatory parameter. With a chromatographic run of less than 10 min, SIM mode provided excellent sensitivity and identification capability due to the monitoring of three ions and the evaluation of their intensity ratio. Limits of detection below 10 ng/L were reached for most of the 66 compounds in the three matrices studied. Accuracy and precision of the method were evaluated by means of recovery experiments at two fortification levels (10 and 100 ng/L), obtaining recoveries between 70% and 120% in most cases and relative standard deviations below 20%. The possibilities of a simultaneous SIM scan method have also been explored for non-target qualitative analysis. The developed method has been applied to the analysis of surface water samples collected from the Mediterranean region of Spain.

Fully automated solid-phase microextraction–fast gas chromatography–mass spectrometry method using a new ionic liquid column for high-throughput analysis of sarcosine and N-ethylglycine in human urine and urinary sediments

A fully automated, non invasive, rapid and high-throughput method for the direct determination of sarcosine and N-ethylglycine in urine and urinary sediments using hexyl chloroformate derivatization followed by direct immersion solid-phase micro extraction and fast gas chromatography–mass spectrometric analysis was developed and validated. The use of a new ionic liquid narrow bore column, as well as the automation and miniaturization of the preparation procedure by a customized configuration of the utilized XYZ robotic system, allowed a friendly use of the GC apparatus achieving a quantitation limit of 0.06 μg L −1 for sarcosine, good repeatability with CV always lower than 7% and reduced analysis times useful for point-of-care testing. The method was then applied for the analysis of 56 samples of urine and urinary sediments in healthy subjects, in those with benign prostatic hypertrophy and in patients with clinically localized prostate cancer. The results obtained showed that the medians of sarcosine/creatinine in urine were 103, 137 and 267 μg g −1 respectively, thus assessing the potential use of sarcosine as urinary biomarker for prostate cancer detection. The highest values of sensitivity (79%) and specificity (87%) were obtained in correspondence of a cut-off value of 179 μg sarcosine (g creatinine) −1, thus by using this cut-off threshold, sarcosine was significantly associated with the presence of cancer ( p < 0.0001). Finally, ROC analyses proved that the discrimination between clinically localized prostate cancer and patients without evidence of tumor is significantly correlated with sarcosine.

Multipesticide residue analysis in maize combining acetonitrile-based extraction with dispersive liquid–liquid microextraction followed by gas chromatography–mass spectrometry

A fast and simple gas chromatography–mass spectrometry (GC–MS) method for determination of forty-one pesticide residues in maize is introduced. The sample preparation involves liquid–liquid partitioning with acetonitrile in presence of anhydrous MgSO 4 and NaCl (QuEChERS) followed by dispersive liquid–liquid microextraction (DLLME) using carbon tetrachloride as extractive solvent and the extract obtained by QuEChERS as dispersive solvent. The main factors influencing DLLME efficiency including extractive solvent type and volume as well as the volume of dispersive solvent were evaluated in this study. The DLLME procedure effectively provides an enrichment of the extract and a cleanup of certain polar matrix components, which can maximize the sensitivity when a single quadrupole MS is used. For validation purposes, recoveries studies were carried out at two concentration levels, yielding recovery rates in the range 70–120% for 82% of the analytes. A good linearity and precision, with relative standard deviations generally below 20% were obtained for all forty-one pesticides. The limits of detection obtained were lower than 19 μg kg −1 for more than 63% of the analytes. In two of a total of ten samples of maize, residues of lindane, tefluthrin, pirimicarb, folpet and bifenthrin were found, although at levels below the maximum limit established for this kind of samples.

Online Comprehensive Two-Dimensional Characterization of Puff-by-Puff Resolved Cigarette Smoke by Hyphenation of Fast Gas Chromatography to Single-Photon Ionization Time-of-Flight Mass Spectrometry: Quantification of Hazardous Volatile Organic Compounds

This work presents the direct coupling of a custom-made smoking machine (SM) to fast gas chromatography combined with single-photon ionization mass spectrometry (GC × SPI-MS) utilizing a six-port, two-position valve for online puff-resolved comprehensive two-dimensional investigation of cigarette smoke. The innovative electron-beam pumped rare gas excimer light source (EBEL) filled with argon provided vacuum ultraviolet (VUV) photons of 9.8 ± 0.4 eV (126 ± 9 nm) for SPI. Puff-by-puff quantification of 14 hazardous volatile organic smoke constituents from the 2R4F Kentucky research cigarette was enabled for two smoking regimes, i.e., ISO and Canadian Intense, after determination of photoionization cross sections. The investigated analytes comprised NO, acetaldehyde, butadiene, acrolein, propanal, acetone, isoprene, furan, crotonaldehyde, isobutanal, butanal, 2-butanone, benzene, and toluene. The determined amounts of these compounds in cigarette smoke agreed excellently with the literature values. Furthermore, the two well-known patterns of puff-by-puff behaviors for these different smoke constituents were obtained for both whole smoke and gas-phase measurements.

Chemical Composition and Acaricidal Properties of Deverra scoparia Essential Oil (Araliales: Apiaceae) and Blends of Its Major Constituents Against Tetranychus urticae (Acari: Tetranychidae)

The essential oil of Deverra scoparia Coss. & Durieu was investigated for its acaricidal activity against the worldwide pest twospotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae). The essential oil was analyzed by fast gas chromatography (GC) and GC-mass spectrometry. The activities of its individual and blended constituents were determined. Our study showed that female mortality increased with increasing D. scoparia oil concentrations, with LD50 and LD90 values at 1.79 and 3.2 mg liter(-1), respectively. A reduction in fecundity had already been observed for concentrations of 0.064, 0.08, and 0.26 mg liter(-1) D. scoparia essential oil. Ten major components, comprising 98.52% of the total weight, were identified; a-pinene was the most abundant constituent (31.95%) followed by sabinene (17.24%) and delta3-carene (16.85%). The 10 major constituents of D. scoparia oil were individually tested against T. urticae females. The most potent toxicity was found with alpha-pinene, delta3-carene, and terpinen-4-ol. The presence of all constituents together in the artificial mixture caused a significant decrease in the number of eggs laid by females, at 0.26 mg liter(-1) (11 eggs), compared with the control (50 eggs). The toxicity of blends of selected constituents indicated that the presence of all constituents was necessary to reproduce the toxicity level of the natural oil.

Experimental design applied to the analysis of volatile compounds in apple juice by headspace solid‐phase microextraction

A simple and fast method based on solid-phase microextraction (SPME) followed by fast gas chromatography (Fast GC) has been developed for the analysis of volatile compounds in Asturian apple juices employed in the cider production. Three different fiber coatings have been checked (PDMS, PDMS-DVB and CAR-PDMS) and PDMS-DVB has been presented to be the most suitable one. Experimental design has been employed in the optimization of extraction factors and robustness assessment. The use of Fast GC allowed the separation of 14 compounds (esters, aldehydes and alcohols) in approximately 4 min, clearly reducing the analysis time when compared to conventional GC. Good linearity, recoveries and repeatability of the solid-phase microextraction were obtained with r(2) values, recoveries and relative standard deviations ranging from 0.9822 to 0.9998, 83.2 to 109.8% and 0.5 to 11.7%, respectively, using standard solution.

New trends in the analysis of the volatile fraction of matrices of vegetable origin: a short overview. A review.

The term ‘volatile fraction’ is a framework including a range of approaches and/or techniques, which produce samples that, while they may have different compositions, are representative of the volatiles characterizing a vegetable matrix, e.g. headspace, essential oils, flavours, fragrances, aromas and extracts prepared through specific techniques. Its study requires analytical methods and technologies able not only to evaluate its composition exhaustively but also to monitor variations of its profile and to detect trace components characterizing the plant being investigated. The strategies of analysis have changed significantly over the last 15–20 years because of the introduction of new approaches, in particular: (i) solventless sample preparation techniques; (ii) fast gas chromatography and related techniques; (iii) new analytical techniques, such as comprehensive gas chromatography (GC); (iv) new operative strategies based on approaches developed for other fields and applied to plant analysis; and (v) data elaboration strategies producing a higher level of information. This article is a short overview on (1) the advancement of analytical techniques and how they can influence strategies and approaches to study the plant volatile fraction, and (2) enantiomer GC and GC-mass spectometry separation using cyclodextrins as chiral selectors. Copyright © 2011 John Wiley & Sons, Ltd.

A simplified Quick, Easy, Cheap, Effective, Rugged and Safe approach for the determination of trihalomethanes and benzene, toluene, ethylbenzene and xylenes in soil matrices by fast gas chromatography with mass spectrometry detection

A method based on simplified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) extraction followed by large-injection volume-fast gas chromatography and mass spectrometry detection has been developed for the determination of trihalomethanes (chloroform, bromodichloromethane, dibromochloromethane and bromoform) and BTEX (benzene, toluene, ethylbenzene and xylenes) in soil samples. The simplified version of QuEChERS used meets the requirements of the “green chemistry” and provides reliable results with high sample throughput, low solvent consumption, little labour and the use of materials commonly employed in laboratories. The GC device used is equipped with a programmable temperature vaporizer (PTV), with a liner packed with Tenax-TA ®. Using the solvent-vent mode, the PTV allows the injection of large volumes of sample, affording an improvement in the sensitivity of the method. The chromatographic conditions used here allowed the separation of the compounds in less than 5.50 min. Good linearity was obtained for all the target compounds, with highly satisfactory repeatability and reproducibility values. The limits of detection were in the 0.2 to 15 μg kg −1 range. The method was validated by the analysis of two certified reference materials.

Detecção em cromatografia gasosa rápida e cromatografia gasosa bidimensional abrangente

The fast gas chromatography and the comprehensive two-dimensional gas chromatography generate peaks much narrower than in conventional gas chromatography. In these techniques, the peak width (at baseline) commonly observed ranges from 1 s to 50 ms, reaching values as small as units of milliseconds. The flame ionization detector and the time of flight mass spectrometer do not present limitation to detect such narrow peaks; however, other detectors present some limitations. Peak distortion, peak tailing and the low quality of the peak mass spectra are the main problems observed. In the present paper it will be presented the basic characteristics of the detectors for gas chromatography and their use to detect narrow

Current mass spectrometry strategies for the analysis of pesticides and their metabolites in food and water matrices.

Analysis of pesticides and their metabolites in food and water matrices continues to be an active research area closely related to food safety and environmental issues. This review discusses the most widely applied mass spectrometric (MS) approaches to pesticide residues analysis over the last few years. The main techniques for sample preparation remain solvent extraction and solid-phase extraction. The QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe) approach is being increasingly used for the development of multi-class pesticide residues methods in various sample matrices. MS detectors-triple quadrupole (QqQ), ion-trap (IT), quadrupole linear ion trap (QqLIT), time-of-flight (TOF), and quadrupole time-of-flight (QqTOF)-have been established as powerful analytical tools sharing a primary role in the detection/quantification and/or identification/confirmation of pesticides and their metabolites. Recent developments in analytical instrumentation have enabled coupling of ultra-performance liquid chromatography (UPLC) and fast gas chromatography (GC) with MS detectors, and faster analysis for a greater number of pesticides. The newly developed "ambient-ionization" MS techniques (e.g., desorption electrospray ionization, DESI, and direct analysis in real time, DART) hyphenated with high-resolution MS platforms without liquid chromatography separation, and sometimes with minimum pre-treatment, have shown potential for pesticide residue screening. The recently introduced Orbitrap mass spectrometers can provide high resolving power and mass accuracy, to tackle complex analytical problems involved in pesticide residue analysis.

Fast GC-MS method for the simultaneous screening of THC-COOH, cocaine, opiates and analogues including buprenorphine and fentanyl, and their metabolites in urine

A fast gas chromatography (GC)-MS method has been developed and validated for the simultaneous screening of different classes of drugs of abuse in urine. Tetrahydrocannabinol metabolite, cocaine, opiates such as morphine, O-6-monoacetylmorphine (O-6-MAM), codeine, opioids such as buprenorphine, methadone, pentazocine, fentanyl and analogues and their main metabolites can be detected and quantified after a simple liquid-liquid extraction in alkaline conditions and derivatisation to obtain the corresponding trimethylsilyl derivatives. The chromatographic separation is performed in a total time of 6 min, using a short GC column (5% phenyl methyl silicone, 10-m length × 0.18-mm internal diameter). The Limits of Detection are satisfactory for forensic purposes for all the substances; the repeatability of concentrations (percent coefficients of variation) are always lower than 15% at high and low concentration levels, and accuracy, intended as % error on the true value, is always lower than 15% for all the analytes. The method can successfully be applied for screening analyses in many fields of forensic toxicology.

Highly Resolved Online Organic-Chemical Speciation of Evolved Gases from Thermal Analysis Devices by Cryogenically Modulated Fast Gas Chromatography Coupled to Single Photon Ionization Mass Spectrometry

Multi-dimensional analysis (MDA) in analytical chemistry is often applied to improve the selectivity of an analytical device and, therefore, to achieve a better overview of a sample composition. Recently, the hyphenation of thermogravimetry with single photo ionization mass spectrometry (TG-SPIMS) using an electron beam pumped excimer lamp (EBEL) for VUV radiation was applied. The concept of MDA has been realized by upgrading the TG-SPIMS system with a quasi comprehensive chromatographic separation step before the soft ionization (TG-GCxSPIMS). The system was characterized by the thermal analysis of diesel fuel, which has often been investigated by the GCxGC-community and is therefore a well-known sample material in MDA. Data from this measurement are used to explain the three-dimensional data structure and the advantages of the online TG-GCxSPIMS as compared to TG-SPIMS. Subsequently, the thermal decomposition behavior of a polymer, acrylonitrile-butadiene-styrene (ABS), is investigated. TG-GCxSPIMS provides a two-dimensional analysis of the evolved gaseous products. TG relevant data are obtained as well as an improved resolution power to separate isobaric molecular structures without losing any fraction of the samples, as is often the case in heart cutting approaches. Additionally, this solution is not associated with any extension of the measurement time. The assignment of the substance pattern to distinct species is improved as compared to solely using mass spectrometry without a preceding separation step. Furthermore, hitherto undetected compounds have been found in the evolved gases from the thermal degradation of ABS. Finally, a first estimation of the limit of detection has been carried out. This results in a significant decrease of the LOD in case of TG-GCxSPIMS (500 ppt for toluene) as compared to 30 ppb, which could be reached with TG-SPIMS.

Application of Fast Gas Chromatography and Fourier Transform Infrared Spectroscopy for Analysis of Lard Adulteration in Virgin Coconut Oil

Lard (LD) and virgin coconut oil (VCO) share some similarities such as having transparent to yellowish color and are solid at room temperature; hence, as a consequent, LD may be a potential oil adulterant in VCO. This study highlights the application of fast gas chromatography with surface acoustic wave detector (GC-SAW system) and Fourier transform infrared (FTIR) spectroscopy combined with chemometrics to analyze the presence of LD in VCO. Binary admixtures of LD in VCO in various percentage concentrations ranging from 1% to 50% (v/v) were assayed using the fast GC-SAW system and FTIR spectroscopy. Using the fast GC-SAW system, ten different chromatogram peaks were identified as the adulterant peaks. One peak in the fast GC-SAW system chromatogram was found to have the best relationship, with a coefficient of determination (R2) value of 0.9344. Furthermore, FTIR spectroscopy coupled with partial least square (PLS) and discriminant analysis (DA) can be successfully developed for quantification and classification of LD in VCO. The results showed that PLS able to predict the LD contents in VCO with equation of \( y = 0.{999} \times + 0.00{6} \), for the correlation between actual value of LD (x) and FTIR predicted value (y) with R2 of 0.9990 at frequency regions of 3,020–3,000 cm−1 and 1,120–1,000 cm−1. DA can classify VCO and that adulterated with LD using the FTIR spectra at the same frequency regions used in quantification.

Rapid assessment of volatile components in Baicao oils by headspace single drop microextrction coupled with gas chromatography

A simple, fast GC method based on headspace single drop microextraction (HS-SDME) was used for the determination of menthol and methyl salicylate in Baicao oils. A special sample pretreatment method was performed by adding 10 microL the oil its methanol solution into 5 mL water in a caped 10 mL sample vial, a 1.5 microL microdrop of N,N-dimethylformamide with benzyl alcohol as internal standard was formed on the pinpoint of microsyringe needle, exposing 5 min at extraction temperature of 40 degrees C. After extraction, 0.5 microL of extract was directely injected into GC for analysis. The determination was carried out on a capillary column (0.53 mm x 30 m) with PEG as the stationary phase with FID as the detector. A temperature programm was employed. The excellent separation and detection of the target components was accomplished. The average recoveries varied between 95.4% and 99.2%, and relative standard deviations were less than 1.9%. The calibration curves were linear in the range of 1.26-80.5 mg x L(-1) for menthol (r = 0.999 0) and 2.49-1.59 x 10(2) mg x L(-1) for methyl salicylate (r = 0.999 1), respectively. The proposed method is proved to be simple, fast, accurate and low cost without complicated sample pretreatment HS-SDME is expected to be widely applied for the analysis of volatile components in traditional Chinese medicines.