Flame Ionization Detection System Research Articles

Method Development for Leachable Furfural Determination in Wood-Based Panels by HPLC-Uv System

Analytical method has been developed and validated to determine free or leachable furfural concentration in wood-based panels. Particleboards obtained from birch wood and suberinic acids binder were chosen as a reference material. Two methods and two solvents were tested. Acetone extracts of the samples were analyzed with gas chromatography (GC) flame ionization detector system. Water extracts were analyzed with high-performance liquid chromatography-ultraviolet spectroscopy (HPLC-UV) system. After the GC data in acetone extracts furfural concentration was below method limit of detection. HPLC-UV data showed that in water extracts furfural concentration was possible to determine. It was concluded that HPLC-UV is suitable and fast method for furfural determination in wood-based panels water extracts.

Fatty acids of follicular fluid phospholipids and triglycerides display distinct association with IVF outcomes

Research questionAre triglyceride fatty acids in the follicular fluid associated with either follicular fluid phospholipid fatty acids or IVF outcomes and, if so, how are they associated? DesignIn a prospective cross-sectional study, 70 women undergoing intracytoplasmic sperm injection were recruited. Follicular fluid phospholipids and triglycerides were separated by thin-layer chromatography. Fatty acids were measured using gas-liquid chromatography and flame ionization detection system. ResultsSignificant differences in fatty acid composition were observed between follicular fluid phospholipid and triglyceride fractions. Phospholipid stearic acid and n-3 polyunsaturated fatty acids, particularly alpha-linolenic acid, were negatively associated with the number of mature oocytes and cleaved embryos, whereas arachidonic acid was in direct correlation with cleavage rate per IVF cycle (β = 0.325, P = 0.022). In the case of triglyceride fraction, total monounsaturated fatty acids, oleic acid in particular, displayed significantly positive associations with the number of oocytes (β = 0.261, P = 0.043) and embryos (β = 0.310, P = 0.018). Furthermore, cleavage rate correlated inversely with palmitic acid (β = –0.359, P = 0.007) and directly with pentadecanoic acid (β = 0.378, P = 0.005). Most of these associations, however, were not independent of predictive fatty acids belonging to phospholipid fraction, according to multivariate analysis. ConclusionsFatty acid compositions of phospholipid and triglyceride fractions from human follicular fluid differentially correlate with IVF cycle parameters.

Microextraction and gas chromatography–flame ionization determination of five antiepileptic drugs in biological samples using amino acid-based deep eutectic ionic liquids

This study investigated the use of amino acid-based deep eutectic solvents (AADESs) in the ultrasound assisted reverse-phase emulsification microextraction (UARPEME) of five antiepileptic drugs (AEDs) from biological samples. The extraction was performed by dispersing the AADES into the sample solution using ultrasonic irradiation. After completing extraction, the sample solution was centrifuged. Then, the pre-concentrated AEDs in the AADES (upper phase) were derivatized by adding phenyltrimethylammonium hydroxide solution to it. The derivatized analytes were then eluted with n-hexane and it was injected directly into the gas chromatography–flame ionization detection (GC–FID) system to determine target analytes after the methylation reaction inside the injection chamber. The effective parameters of the proposed AADES–UARPEME method that comprises three consecutive extraction, derivatization and elution steps, were optimized using one Taguchi orthogonal array design and two central composite designs and evaluated by analysis of variance. The optimized method was successfully implemented to analyze AEDs in the human biological samples (serum, urine, breast-milk and hair) and acceptable results were obtained. The resultant calibration curves were linear over the concentration range of 0.5–850 μg/L (R2 > 0.998). The estimated limits of detection and quantification were lower than 0.5 μg/L and the improvement factors were between 1378 and 1409. The intra- and inter-day repeatability values varied below 5.3% (n = 5) and the relative recovery values were calculated between 90 and 110% for all samples.

Composition and Atmospheric Reactivity of Ambient Volatile Organic Compounds(VOCs)in the Urban Area of Nanjing, China

Online gas chromatography with flame ionization detection (GC-FID) systems were employed to observe 56 species of volatile organic compounds (VOCs) in the environmental atmosphere in Nanjing in 2015. The results showed that the annual volume fraction of VOCs was (17.49±11.35)×10-9. The highest concentration of VOCs was in April (22.21×10-9), and the lowest in July (12.39×10-9). Diurnal values of VOCs concentration had no obvious variations. Alkanes, alkenes, aromatics, and acetylene accounted for 56.51%, 11.06%, 24.62%, and 7.81%, respectively. Propane (15.26%), ethane (14.14%), acetylene (7.81%), toluene (6.97%), n-butane (6.23%), ethylene (5.23%), isobutane (4.34%), propylene (4.13%), isoprene (4.12%), and m/p-xylene (4.06%) were the most abundant VOCs species. The average ratio of toluene/benzene (T/B) was 2.02, indicating that the atmospheric VOCs were mainly affected by emissions of motor vehicles, especially gasoline vehicles. The average ratio of ethane/ethyne (E/E) was 2.24, showing that the plume had aged. The hydroxyl radical (·OH) loss rate(L·OH) and ozone formation potential(OFP)were applied to assess the chemical reactivity of VOCs. The atmospheric activity of VOCs was higher in the winter and spring than in the summer and autumn. Aromatics and alkenes were the most important contributors to L·OH and OFP. Their contributions to L·OH and OFP were 46.96% and 41.58%, and 33.73% and 39.86%, respectively. Propylene, ethylene, and xylene were the most active species.

Estimation of Dietary Intake Concentration of Polycyclic Aromatic Hydrocarbon (PAH) Carcinogens from <i>Tilapia zilli</i> Commercially Available from Escravos River, Nigeria

The Concentrations of Polycyclic Aromatic Hydrocarbons in the organs of a commonly consumed Tilapia zilli from Escravos River in Delta State, Nigeria were evaluated to ascertain the level of their bioaccumulation and the possible human health risks associated with their consumption. Samples were analysed with a Gas Chromatographic Flame Ionization Detector system and results were subjected to a one-way Analysis of Variance (ANOVA) to test for the significant level of the parameters across the groups. The level of significance was above 95% and the results were presented as mean ± standard error. The values of PAHs reported followed different trends. The muscle had the highest average concentration (313.43±1.64 mg/kg) followed by kidney (266.72±0.36 mg/kg) and the liver (266.17±0.81 mg/kg) while the gills had the lowest average concentration (192.96±1.09 mg/kg). The average concentrations of PAH reported in this research are highly above the EU recommended benchmark (2 µg/kg). The reported ailments from the communities cut across Escravos river could be traced to long term exposure of humans to these polycyclic aromatic hydrocarbons in the sea foods which are transferred into their food chain because of their high level of dependency for protein source.

A method for the gross analysis of global protein acylation by gas-liquid chromatography.

Protein acylation is a posttranslational modification in which an amino acid residue of a protein is acylated by a fatty acid. This process plays a key role in regulating proteomic function. Studies of protein acylation have relied on the development and application of extremely complicated molecular methods. However, global protein acylation can be profiled following hydrolysis of fatty acyl groups from cellular proteins. The present study aimed to develop a method for analysis of global protein acylation using gas-liquid chromatography (GLC). The total protein was extracted from the human hepatocellular carcinoma (HepG2) cell line. Protein sedimentation and extensive wash were combined with differential O-, S-, or N-acyl hydrolysis using sodium hydroxide (NaOH), hydroxylamine (NH2 OH), or hydrochloric acid (HCl), respectively. GLC with a flame ionization detector system was used to analyze changes in the fatty acid composition of the released lipids. The effect of selective inhibition of monounsaturated fatty acid (MUFA) synthesis on global protein acylation and the expression of reprogramming markers were determined to further validate the proposed profiling approach. In all hydrolysis conditions, the amount of myristate released was significantly higher than of other fatty acids. Notable differences were observed in the release of individual fatty acids among the hydrolyzing agents. Only NH2 OH could release significant amounts of palmitoleate (>2.5-fold vs. NaOH and HCl). The acylation assay indicates that treatment with a chemical inhibitor of monounsaturated fatty acid synthesis led to an overall increase in saturated fatty acid O- and N-acylation, and a decrease in palmitoleate O- and S-acylation of cellular proteins (<-15%). This was accompanied by significant reductions in the gene expression of the reprogramming markers Oct4 (-26%, P < 0.01) and Sox2 (-40%, P < 0.01). GLC-based analysis of global protein acylation affords a semi-quantitative method that can be used to assess the gross changes in the protein acylation profile during cell differentiation and reprogramming. © 2018 IUBMB Life, 71(3):340-346, 2019.

Complex mixture quantification without calibration using gas chromatography and a comprehensive carbon reactor in conjunction with flame ionization detection.

Quantification of complex carbon-containing mixtures is typically a very time-intensive task with regards to the calibration process. A gas chromatograph with a flame ionization detector yields strong responses to organic compounds and provides a wide linear range over many orders of magnitude; however, responses for highly functionalized and heteroatom-containing compounds can be variable. Here, a commercial Polyarc microreactor unit, placed before the flame ionization detector, was investigated as a means of normalizing carbon response across all compounds. The device includes two catalytic reaction chambers, ultimately converting all carbon atoms to methane evenly for flame ionization detection. Three groups of different complex mixtures from n-alkane to terpene and polymer mixtures were analyzed to evaluate the potential for calibration-free quantitation of the new detector arrangement. We have obtained accurate quantification results without time-consuming calibration processes. The quantification of a terpene mixture and a polymer mixture confirms the ability of the detector for analyzing samples that either have complex physical or structural properties or wide concentration range. In summary, compared to other detectors, this methanizer - flame ionization detection system provides a simplified workflow, which can eliminate calibration steps and increase throughput.

Health risk assessment associated with volatile organic compounds in a parking garage

Most volatile organic compounds are considered potentially harmful air pollutants to the environment and most importantly human health. The present work investigated the concentrations of 72 volatile organic compounds commonly emitted from the vehicular exhausts at a hospital parking garage. The objective was set to assess the associated health risk due to inhalation of these compounds during weekdays versus weekends. Carcinogenic and non-carcinogenic health risks were assessed using the US Environmental Protection Agency conventional approach. A total of 112 air samples were collected inside the hospital parking garage using six-liter evacuated Silonite™-coated polished stainless steel canisters. Triplicate sampling was used for quality assurance/quality control purposes. The air samples were analyzed using the gas chromatography with flame ionization detection system, which followed the US Environmental Protection Agency TO-15 Method. The overall 24-h concentrations of benzene, toluene, ethylbenzene, and xylenes were 6.78, 31.14, 11.35, and 27.85 μg/m3, respectively. These values were comparable to values reported in Europe, North America, and Asia. The weekend concentrations were lower than the weekday ones. Halogenated compounds had the highest contribution of volatile organic compounds groups to total concentrations in both weekday and weekend. The weekday and weekend concentrations temporal cycles were characterized, and they were correlated with the traffic activity inside the parking garage. Two of the measured compounds (i.e., tetrachloromethane and 1,2-dibromoethane) were discovered to pose definite cancer risk. To our knowledge, this is the first study in the region which looks at volatile organic compound levels in a parking garage and the associated health risks.

Routine quantification of 54 allergens in fragrances using comprehensive two‐dimensional gas chromatography‐quadrupole mass spectrometry with dual parallel secondary columns. Part I: Method development

AbstractThe forthcoming extension of the regulated fragrance allergen number is raising a challenge: the previously developed quantification methods need to be drastically improved in terms of rapidity, without altering their reliability. This work describes a procedure based on comprehensive bidimensional gas chromatography, hyphenated with a low‐cost quadrupole mass spectrometer (GCxGC‐QMS). The second chromatographic dimension was operated in a dual configuration, consisting of two parallel secondary columns, one being connected to the QMS, the other to a flame ionization detector (FID). This not only allowed optimization of the chromatographic gas flows when compared to the usual single second dimension, but it also enabled the use of the FID signal to extend the quantification range from 2 to 10,000 mg/kg. The QMS was used at a low level (2‐100 mg/kg), where coelutions are frequent, and the FID was used for the most abundant analytes (100‐10,000 mg/kg) with a low risk of significant interferences. To assess the identity and purity of the analyte peak at low level, we propose a strategy and summarize it in a decisional tree. To our knowledge, this represents the first fully developed quantification method based on a GCx2GC‐QMS/FID system. In contrast to other methods, it enables the quantification of a wide variety of analytes in fragrances in a single run, without requiring a series of sample dilutions to match the calibration range.

Assessment of spatial variation of ambient volatile organic compound levels at a power station in Kuwait

ABSTRACTTwenty-four-hour integrated ambient air samples were collected in canisters at 10 locations within Kuwait’s major power station: Doha West Power Station to assess the spatial distribution of volatile organic compounds (VOCs) within the perimeter of the station. A total of 30 samples, i.e., three samples per location, were collected during February and March. The samples were analyzed using a gas chromatography with flame ionization detection (GC-FID) system and following the U.S. EPA Method TO-14A with modification. The results reflected the emission activities on the site and the meteorological conditions during sampling. Generally speaking, there was a negative correlation between the ambient temperature and the VOC concentrations, which indicates the sources were local. The halogenated compounds formed the highest proportion (i.e. 50–75 %) of the total VOC concentrations at the ten locations. 1,2,4-Trichlorobenzene and Vinyl Chloride concentrations were the highest amongst the other halogenated compounds. The aromatic compounds formed the least proportion (i.e. 1–4%) of the total VOC levels at all locations with Toluene having the highest concentrations amongst the aromatic compounds at seven locations. Propene, which is a major constituent of the fuel used, was the highest amongst the aliphatic compounds. The findings of this study and other relevant work suggests the measured VOC levels were the highest over the year, nevertheless, further work is required to assess the precisely temporal variation of VOC due to change in meteorological conditions and the emission rates.Implications: Assessment of VOC concentrations around a power plant in Kuwait during the peak season showed halogenated compounds to be the dominant group. The calculated indoor concentrations were lower than those reported in a residential area about 12 km away.

High performance mini-gas chromatography-flame ionization detector system based on micro gas chromatography column.

Monitoring Volatile organic compounds (VOCs) was a very important measure for preventing environmental pollution, therefore, a mini gas chromatography (GC) flame ionization detector (FID) system integrated with a mini H2 generator and a micro GC column was developed for environmental VOC monitoring. In addition, the mini H2 generator was able to make the system explode from far away due to the abandoned use of a high pressure H2 source. The experimental result indicates that the fabricated mini GC FID system demonstrated high repeatability and very good linear response, and was able to rapidly monitor complicated environmental VOC samples.

Analysis of essential oils isolated by steam distillation from Swinglea glutinosa fruits and leaves

Essential oils obtained by steam distillation from Swinglea glutinosa (Blanco) Merr. fruit peel or leaves were analyzed by gas chromatography with flame ionization and mass spectrometry detection systems. A total of sixty-seven compounds were found, sixty-four of which were common to both oils, although present in different relative amounts. The main component of the essential oils obtained from S. glutinosa fruit peel or leaves was trans-nerolidol (19.1% and 28.4%, respectively). Sesquiterpene hydrocarbons (50%) and their oxygenated analogues (35%) were the most abundant compound types in the leaf oil. Monoterpene hydrocarbons (51%) were the principal compound family found in the oil obtained from fruit peels.

A Rapid and Sensitive Method for the Analysis of Pyrethroid Pesticides Using the Combination of Liquid–Liquid Extraction and Dispersive Liquid–Liquid Microextraction

For the first time, combination of liquid–liquid extraction and dispersive liquid–liquid microextraction (LLE‐DLLME) is reported in this study. The method is efficient and was applied to the analysis of pyrethroid pesticides (fenpropathrin, sumithrin, cyhalothrin, permethrin, and deltamethrin) in fruit juices and fresh grape using gas chromatographic techniques with flame ionization detection system and mass spectrometric detection system. Five milliliter n‐hexane was used for the traditional liquid–liquid extraction of target analytes from 50 mL aqueous samples. After manual shaking, the supernatant phase (n‐hexane) was transferred into a test tube to which 0.75 mL dimethylformamide (DMF) was added then and the tube was shaken manually. After centrifugation, 0.6 mL of DMF was removed and used in a following DLLME procedure in which the extraction solvent was 20 μL of 1,1,2‐trichloroethane. Extraction with the optimized conditions resulted in linear analytical signals within the range 0.5–1200 μg L−1 and the limits of detection and quantification were in the ranges of 0.1–15 and 0.4–50 μg L−1, respectively. The method also showed high enrichment factors (2570–6835) and relatively good extraction recoveries (26–68%). Finally, the method was successfully applied to determination of analytes in tap water, strawberry juice, apricot juice, and fresh grape.

Characterization of the aromatic profile of the Italia variety of Peruvian pisco by gas chromatography-olfactometry and gas chromatography coupled with flame ionization and mass spectrometry detection systems

Thirty-three commercial pisco samples made with Italia grapes in five different regions in Perú have been evaluated by gas chromatography-olfactometry (GC-O) and chemical quantitative analysis for the first time. The GC-O study has revealed that the Peruvian pisco made from this aromatic variety of grape (Italia) has an aroma profile composed of twenty-five odorants. Only one of them could not be identified (LRIDB-WAX 2313). Most of the odorants are fermentation-related, while guaiacol, β-damascenone, geraniol and linalool come from the grape. A total of sixty-two compounds have been analyzed following two different methods. As a result of these analyses, a volatile profile quite typical of a wine distillate was obtained. Terpenes play a relevant aromatic role in piscos elaborated from aromatic varieties of grapes. Italia piscos are particularly highlighted because of their high levels of linalool. This terpene has exceeded its odor threshold in 28 of the 33 samples, reaching odor activity value (OAV) up to 10units. Other terpenes such as geraniol and β-citronellol have presented OAVs higher than 1 in one and five samples respectively. Compared to the composition of other aromatic piscos, the Italia variety exhibited considerably higher concentrations of some volatile compounds (nerol and acetic acid) and lower levels of some ethyl esters (ethyl lactate, diethyl succinate and ethyl hexanoate). Furthermore, when compared with other distillates it can be concluded that in general aromatic piscos seem to be characterized by high levels of β-phenylethanol and β-phenylethyl acetate (with the exception of some orujo and grappa compositions), and also by low levels of some ethyl esters, 1-hexanol and ethyl acetate. In general, the chemical differences may be sufficient to classify the samples by origin. Quantitative data revealed that samples from Ica are the richest in several aromatic compounds such as terpenes, β-damascenone and β-phenylethyl acetate and samples from Moquegua are the poorest in phenol compounds, which can have an impact from a sensory point of view.

Gas chromatography–mass spectrometry based metabolic profiling for the identification of discrimination markers of Angelicae Radix and its application to gas chromatography–flame ionization detector system

Gas chromatography (GC)-based metabolomics technologies were applied for quality control of Angelicae Radix, an herbal medicine commonly used in Japan and China. Since Angelica roots are priced and graded differently based on their species and cultivation area, there is a need for a simple and reproducible method to discriminate Angelica roots. Here, we used GC-MS profiling data to construct a discrimination method for species and cultivation area of A. Radix. Seventy-six primary metabolites were identified. The quality factors of A. Radix were successfully classified using metabolic profiling and the orthogonal projections to latent structures-discriminant analysis (OPLS-DA) technique. Sorbitol and a glucose/4-aminobutyric acid combination were chosen as bio-markers from S-plot of OPLS-DA. Application of these selected bio-markers to a more practical and cost-efficient system, namely gas chromatography-flame ionization detector (GC-FID) system were also assessed. As a result, the same separations of sorbitol, glucose and 4-aminobutyric acid in box plots were obtained from GC-FID data. Our results demonstrate that GC-based metabolic markers can be readily applied for the establishment of a practical quality control method for A. Radix.

Application of ultrasound-assisted emulsification microextraction for determination of benzene, toluene, ethylbenzene and o-xylene in water samples by gas chromatography

An ultrasound-assisted emulsification microextraction procedure has been developed for determination of benzene, toluene, ethylbenzene and o-xylene (BTEXs) in water samples by gas chromatography–flame ionization detection system (GC–FID). The method is based on the dispersion of microvolumes of an organic solvent in the aqueous phase and subsequent extraction of target analytes into the fine droplets of the organic phase. After centrifugation, the sedimented phase is separated and directly injected to the GC system. The effects of experimental parameters such as type and volume of organic solvent, sonication and extraction times, salt effect and centrifugation time were evaluated and optimized. Under the optimum conditions a relatively broad dynamic linear range of 0.01–20μgmL−1 and a good linearity (R2) ranging from 0.9986 to 0.9998 were obtained for all the target analytes. The repeatability and reproducibility for 2μgmL−1 of each analyte (n=5) were in the range of 1.58–5.75% and 2.54–5.89%, respectively. The limit of detection (S/N=3) and preconcentration factor were in the range of 0.4–2μgL−1 and 653–835, respectively. Finally, the purposed method has been successfully applied to the determination of BTEX compounds in different water samples and good spiked recoveries over the range of 94–99% were obtained.

Characterizing non-methane volatile organic compounds emissions from a swine concentrated animal feeding operation

Emissions of non-methane volatile organic compounds (NMVOCs) were determined from a swine concentrated animal feeding operation (CAFO) in North Carolina. NMVOCs were measured in air samples collected in SUMMA and fused-silica lined (FSL) canisters and were analyzed using a gas chromatography flame ionization detection (GCeFID) system. Measurements were made from both an anaerobic lagoon and barn in each of the four seasonal sampling periods during the period June 2007 through April 2008. In each sampling period, nine to eleven canister samples were taken from both the anaerobic lagoon and barn over a minimum of four different days during a period of w1 week. Measurements of meteorological and physiochemical parameters were also made during the sampling period. In lagoon samples, six NMVOCs were identified that had significantly larger emissions in comparison to other NMVOCs. This included three alcohols (ethanol, 2-ethyl-1-hexanol, and methanol), two ketones (acetone and methyl ethyl ketone (MEK)) and an aldehyde (acetaldehyde). The overall average fluxes for these NMVOCs, ranged from 0.18 m gm �2 min � 1 for 2-ethyl-1-hexanol to 2.11 m gm �2 min �1 for acetone, with seasonal fluxes highest in the summer for four (acetone, acetaldehyde, 2-ethyl-1-hexanol and MEK) of the six compounds In barn samples, there were six NMVOCs that had significantly larger concentrations and emissions in comparison to other NMVOCs. These consisted of two alcohols (methanol and ethanol), an aldehyde (acetaldehyde), two ketones (acetone and 2,3-butanedione), and a phenol (4-methylphenol). Overall average barn concentration ranged from 2.87 ppb for 4-methylphenol to 16.12 ppb for ethanol. Overall average normalized barn emission rates ranged from 0.10 g day �1 AU �1 (1 AU (animal unit) ¼ 500 kg of live animal weight) for acetaldehyde to 0.45 g day �1 AU �1 for ethanol. The NMVOCs, 4methylphenol and 2,3-butanedione, which have low odor thresholds (odor thresholds ¼ 1.86 ppb and 0.068e0.264 ppb for 4-methylphenol, and ¼ 4.37 ppb and 1.42e7.39 ppb for 2-3-butanedione) and an offensive odor were identified in canister samples. Both 4-methylphenol and 2,3-butanedione barn concentrations exceeded their odor thresholds frequently. HAPs were identified in lagoon samples (methanol, acetaldehyde and MEK) and barn samples (methanol, acetaldehyde and 4-methylphenol) that were also classified as NMVOCs with significantly larger lagoon and barn emissions in comparison with other NMVOCs. The overall average lagoon fluxes and overall average normalized barn emissions for NMVOCs reported in this paper were used to estimate their North Carolina swine CAFO emissions. Of the NMVOCs, ethanol was estimated to have the largest North Carolina swine CAFO emission at 206,367 kg yr �1 . The barns were found to have higher emissions than the lagoons for all NMVOCs, contributing between 68.6 to w100% of individual compounds estimated North Carolina swine CAFO emissions.

A new aerosol collector for quasi on-line analysis of particulate organic matter: the Aerosol Collection Module (ACM) and first applications with a GC/MS-FID

Abstract. In many environments organic matter significantly contributes to the composition of atmospheric aerosol particles influencing its properties. Detailed chemical characterization of ambient aerosols is critical in order to understand the formation process, composition, and properties of aerosols and facilitates source identification and relative contributions from different types of sources to ambient aerosols in the atmosphere. However, current analytical methods are far from full speciation of organic aerosols and often require sampling times of up to one week. Offline methods are also subjected to artifacts during aerosol collection and storage. In the present work a new technique for quasi on-line compound specific measurements of organic aerosol particles was developed. The Aerosol Collection Module (ACM) focuses particles into a beam which is directed to a cooled sampling surface. The sampling takes place in a high vacuum environment where the gas phase from the sample volume is removed. After collection is completed volatile and semi-volatile compounds are evaporated from the collection surface through heating and transferred to a detector. For laboratory characterization the ACM was interfaced with a Gas Chromatograph Mass Spectrometer, Flame Ionization Detector system (GC/MS-FID), abbreviated as ACM GC-MS. The particle collection efficiency, gas phase transfer efficiency, and linearity of the ACM GC-MS were determined using laboratory generated octadecane aerosols. The ACM GC-MS is linear over the investigated mass range of 10 to 100 ng and a recovery rate of 100% was found for octadecane particles. The ACM GC-MS was applied to investigate secondary organic aerosol (SOA) formed from β-pinene oxidation. Nopinone, myrtanal, myrtenol, 1-hydroxynopinone, 3-oxonopinone, 3,7-dihydroxynopinone, and bicyclo[3,1,1]hept-3-ene-2-one were found as products in the SOA. The ACM GC-MS results are compared to quartz filter samples taken in parallel to the ACM GC-MS measurements. First measurements of ambient atmospheric aerosols are presented.

Capillary gas chromatographic analysis of pyrrolidinedithiocarbamate metal chelates

Pyrrolidinedithiocarbamate (PDTC) chelates of Zn(II), Cu(II), Ni(II), Co(III), Fe(III), Mn(II), Cr(III), and VO(II) were analysed by capillary GC on a DB-1701 column (30 m x 0.25 mm id) with flame ionisation detection (FID). Linear calibrations were attained within "1-30 microg/mL" for Ni(II), Fe(III), Mn(II), Cr(III), Cu(II), and VO(II), and within "2-50 microg/mL" for Co(III) and Zn(II). The limits of detection were in the "150-500 ng/mL" range, corresponding to 15-50 pg amounts reaching the FID system. The optimised method was applied to the determination of Cu(II) and Ni(II) in coins, and that of Zn(II), Cu(II), Ni(II), Fe(III), Mn(II), Cr(III), and VO(II) in pharmaceutical preparations with relative standard deviations within 1.1-5.2%. The results obtained are in good agreement with sewage water samples and the declared values for the pharmaceutical formulations, or with the results of AAS of metal contents in coins, pharmaceutical preparations, and sewage water samples.

Analysis of free and conjugated phytosterols in tobacco by an improved method using gas chromatography–flame ionization detection

An improved and simple method using capillary gas chromatography coupled with a flame ionization detection system (GC–FID) has been developed for quantitative analysis of free and conjugated phytosterols in tobacco. Direct acid and alkaline hydrolysis were first introduced into tobacco analysis to liberate free phytosterols from conjugates, followed by extraction with hexane, derivatization to trimethylsilyl ether derivatives and finally GC quantitative determination. The generality and applicability of this improved method for analyzing free and conjugated phytosterols in tobacco were validated after a series of optimization and comparison were done. Compared with traditional methods, this improved method not only simplified procedures, but also saved time and solvent. The limits of detection (LODs) of phytosterols varied from 0.35 to 0.10 μg mL −1, the relative standard deviations (RSD) were from 2.3% to 3.3% and recovery ranged from 87% to 99%. The analysis results showed that total phytosterols’ content in tobacco ranged from 1.0 to 2.5 mg g −1, and most phytosterols existed as conjugates, only approximately 15–25% phytosterols existed in free-form. Ergosterol was only found in mildewy flued-cured tobacco and the level was approximately 0.2–0.25 mg g −1 .