Flame Ionization Detection Method Research Articles

Development and Optimization of a SPME-GC-FID Method for Ethanol Detection

A solid-phase microextraction (SPME) injection gas chromatography was validated with the flame ionization detection method (GC-FID) using a capillary column to detect ethanol. The method was used to determine ethanol in fluids with biomedical, clinical, and forensic importance, including water, phosphate-buffered saline (PBS), and artificial sweat. The strategy produced good peak resolution and showed a linear correlation between the concentration and peak areas for ethanol in all matrices. The inter- and intra-day precisions of the method were below 15.5% and 6.5%, respectively, varying according to the matrix. The method achieved detection limits below 1.3 mg/L, varying according to the matrix. Lower limits were obtained for the aqueous solution (0.22 mg/L), followed by the PBS solution (0.96 mg/L), and finally, the sweat solution (1.29 mg/L). This method is easy to perform and suitable for use in routine clinical biochemistry and forensic laboratories, allowing ethanol detection at lower concentrations using lower temperature and time of extraction, when compared with other studies.

Head Space Single Drop Micro Extraction Gas Chromatography Flame Ionization Detection (HS-SDME-GC-FID) Method for the Analysis of Common Fatty Acids.

Post-marketing/surveillance studies show that most of the many vegetable oils that are sold with health-promoting claims or statements with high nutritional values and are beneficial against diseases are off-limits of related monographs/criteria. Defining the oil with a fast, cheap, and efficient analytical method is needed to express fatty acids in any herbal product to authenticate, trace, specify, and classify the content.The majority of the after marketing/surveillance studies shows that most of the many vegetable oils that are sold with health-promoting claims or statements with high nutritional values and are beneficial against diseases are off-limits of related monographs/criteria. Defining the oil with fast, cheap and efficient analytical method to express fatty acids in any herbal product, to authenticate, trace, specify and classify the content is needed. Here, we define a new simple tool with a headspace single drop microextraction (HS-SDME) method coupled with a gas chromatography-flame ionization detector (GC-FID) for the analysis of common fatty acids (FAs) in oils. Linolenic acid, γ-linolenic acid, and linoleic acid in olive oil, thyme oil, and fish oil were determined. Derivatization was performed with 0.2 mL of 2 mol/L KOH in methanol to transfer the FAs of oils into their methyl esters (FAMEs). Then, FAMEs were extracted using a head space single drop, which is 2.0 μL of sodium dodecyl sulfate:1-butanol (1:3, v/v) mixture. The most suitable extraction condition was that 360 μL of the FAMEs, 2.0 mL vial, 0.07 g NaCl as a salting-out effect, 45 °C extraction temperature, and 35 min extraction time. The precision of the method was below 12%, with accuracy validated by the GC-FID reference method.The most suitable extraction condition was that 360 μL of the fatty acid methyl esters (FAMEs), 2.0 mL vial, 0.07 g NaCl as a salting-out effect, 45 °C extraction temperature, and 35 min extraction time. The precision of the method was below 12% with an accuracy validated by the GC-FID reference method. The HS-SDME can be used effectively for extracting FAs from oils for improved analysis of other FAs. The method is of direct importance and relevance for the herbal, pharmaceutical, and cosmetics industries.The HS-SDME can be used for effectively for extracting fatty acids from oils for improved analysis of other fatty acids while the method is direct importance and relevance for herbal, pharmaceutical, cosmetics industry.

A novel validated gas chromatography flame ionization detector method for measuring methanol and ethanol in blood samples using a solvent partitioning extraction technique

A novel validated gas chromatography flame ionization detector method for measuring methanol and ethanol in blood samples using a solvent partitioning extraction technique

Endogenous n-Alkanes in Vegetable Oils: Validation of a Rapid Offline SPE-GC-FID Method, Comparison with Online LC-GC-FID and Potential for Olive Oil Quality Control.

The potential of endogenous n-alkane profiling for the assessment of extra virgin olive oils (EVOO) adulteration (blends with cheaper vegetable oils) has been studied by relatively few authors. Analytical methods used for this purpose often involve tedious and solvent-intensive sample preparation prior to analytical determination, making them unattractive. A rapid and solvent-sparing offline solid phase extraction (SPE) gas chromatography (GC) flame ionization detection (FID) method for the determination of endogenous n-alkanes in vegetable oils was, therefore, optimized and validated. The optimized method demonstrated good performance characteristics in terms of linearity (R2 > 0.999), recovery (on average 94%), and repeatability (residual standard deviation, RSD < 11.9%). The results were comparable to those obtained with online high-performance liquid chromatography (HPLC)-GC- FID ( RSD < 5.1%). As an example of an application to prove the potentiality of endogenous n-alkanes in revealing frauds, the data set obtained from 16 EVOO, 9 avocado oils (AVO), and 13 sunflower oils (SFO), purchased from the market, was subjected to statistical analysis and principal component analysis. Two powerful indices, namely (n-C29 + n-C31)/(n-C25 + n-C26) and n-C29/n-C25, were found to reveal the addition of 2% SFO in EVOO and 5% AVO in EVOO, respectively. Further studies are needed to confirm the validity of these promising indices.

Heat treatment effect on tocopherols, total phenolics and fatty acids in table olives (Olea europaea L.)

The olive fruits are rich source of oil, vitamins, minerals, organic acids and pigments. The fruits contain high level of bioactive compounds. The aim of this study was to examine the effect of heat treatment on tocopherols, total phenolics and antioxidant activity in green and black olives, as well as their fatty acid composition. The instrumental methods used in this experiment were high performance liquid chromatography (HPLC), gas chromatography with flame ionization detection (GC/FID) and spectrophotometric methods. The results revealed that the β+γ-tocopherols content after the heat treatment had the biggest reduction, which was 68.4% for green and 80.2% for black olives. Also, a significant loss of total phenolic content was observed after heat treatment in green and black olives by 18.6% and 18.4%, respectively, as well as antioxidant activity (decrease up to 28.1%). The most abundant fatty acids in green and black olives were oleic (C18:1), palmitic (C16:0) and linoleic acid (C18:2). The changes in fatty acids composition during the heat treatment occurred mostly at the level of polyunsaturated fatty acids, especially linolenic acid (C18:3) in black olives had the significant reduction (by 57.4%) in relation to the initial quantity.

A simple and universal headspace GC-FID method for accurate quantitation of volatile amines in pharmaceuticals.

Volatile amines are reagents commonly used in pharmaceutical manufacturing of intermediates, active pharmaceutical ingredients (APIs), and drug products as participating regents for chemical reactions and optimization of product yield. Due to their compound specific daily allowable intake, residual volatile amines are required by regulatory agencies to be monitored and controlled in pharmaceutical products intended for human consumption. However, the accurate quantification of residual volatile amines in pharmaceutical entities can often be challenging as these analytes may chemically react and/or interact with the sample matrix. Herein, we describe a simple and universal headspace gas chromatography with flame ionization detection (HS-GC-FID) method capable of separating 14 commonly used volatile amines. The chemical activity of the volatile amines with the API matrix were mitigated by using 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as an additive to reduce matrix effects in conventional high-boiling diluents. The addition of DBU drastically improved the detectability and method accuracy of the residual volatile amines in an acidic API, namely, Ketoprofen®. Additionally, DBU was employed as a GC deactivation reagent to ensure interfacial adsorption of the analytes to GC components were reduced, thereby improving method precision. Method validation showed acceptable linearity, limit of detection, limit of quantitation, solution stability, precision, and robustness. Separation specificity, evaluated by observing the chromatographic resolution of the volatile amines with one-another and against a set of 23 common residual solvents, were shown to be acceptable for most peak pairs.

Full evaporation headspace technique with gas chromatography as a microchemical method for the rapid determination of gamma-hydroxybutyric acid (GHB) in serum samples

The misuse of GHB as a knockout agent continues to increase. A full evaporation technique with headspace gas chromatography and flame ionization detection (FET-HS-GC-FID) method has been developed for the rapid determination of GHB (gamma-hydroxybutyric acid; “liquid ecstasy”) in serum samples. GHB occurs as an endogenous substance in low concentrations in mammals, is used as a recreational drug and misused as an agent in drug-facilitated sexual assaults or robbery as “knock out drops” in higher concentrations. Rapid determination of substances is particularly important in emergency analysis, especially in the case of unconscious patients.The FET-HS-GC-FID method developed in this paper operates with a sample volume of only 8 µL serum and provides slightly better validation data than the comparison method, which works with 200 µL serum. In order to be able to detect the low-volatile GHB, this is in situ converted into the high volatile lactone under acidic conditions. A thermostatting time of 20 min at 130 °C is sufficient for the lactonization.The FET-HS-GC-FID method enables the detection of GHB to GBL (gamma-butyrolactone) with a limit of detection (LOD) of 1.25 mg L−1, and a limit of quantification (LOQ) of 4.26 mg L−1 in serum samples. The method shows a good precision intraday (7.2 and 6.4 %) and interday (7.8 and 5.6 %) for both the low (lQC) and the high quality control (hQC) sample and a calibration curve determination coefficient (R2) of 0.999.The comparison of 100 spiked serum samples with GHB show an excellent agreement between the conventional and the new developed FET-HS-GC-FID method with a R2 of 0.984 and the results of the proficiency tests showed a very good agreement with the target values and were in all cases within the assessment limits.

A Gas Chromatography Flame Ionization Detector Method for Rapid Simultaneous Separation and Determination of Six Active Ingredients of Anticold Drug

Aims:To establish a rapid and simultaneous determination of multiple effective ingredients in anti-cold drugs.Background:Anti-cold drugs are stock medicines at home, and most anti-cold formulations are compound preparations. Although the active ingredients of compound preparations have significant effects on the treatment of colds, the excessive dosage or long-term use can produce a series of adverse reactions, including dependence, liver and kidney function damage, digestive system reaction, blood system damage. Now, there are many mature methods for analyzing the active ingredients of anti-cold drugs. However, these methods may have shortcomings, such as a long analysis time or a small number of analysis components.Objective:Establish a gas chromatography-flame ionization detector method for the simultaneous determination of six active ingredients, including acetaminophen, dextromethorphan hydrobromide, pseudoephedrine hydrochloride, chlorpheniramine maleate, diphenhydramine hydrochloride, and caffeine in anti-cold drugs.Method:After the standard was accurately weighed, dissolved in ethanol, filtered by 0.22 μm membrane and ultrasonically degassed, the gas chromatograph was used for detection. After the actual sample was removed from the coating, ground and crushed, accurately weighed, dissolved in ethanol, filtered by 0.22 μm membrane and ultrasonically degassed, the gas chromatograph was used for detection.Result:The six components can be completely separated within 7.0min. This method has good sensitivity, precision, accuracy and recovery rate. Under the optimum testing conditions, the limit of detection was 0.360-2.50μg/mL, the limit of quantification was 1.20-8.30μg/mL. The calibration curves showed good linearity (R2≥0.9932) over the investigated concentration range between 1.20 and 400μg/mL. The recoveries were 89.2% to 109.2%. The RSD of intra-day precision was less than 1.0%. The RSD of inter-day precision was less than 3.2%. The established method was used to determine the ingredients of three anti-cold drugs on the market, and the results showed that the method can accurately determine the ingredients.Conclusion:The method can quickly and simultaneously determine multiple active ingredients in anti-cold medicines. Compared with the published methods in literature, the proposed method has the advantages of fast, the number of analysis components wide application range, convenience, low cost, etc. It provides a reference method for quality control of active ingredients of anti-cold drugs.

A new source of omega-3 and gamma tocopherol: Fig (Ficus carica L.) seed oil

Essential fatty acids are oils which cannot be synthesized in the human body and which must be acquired from elsewhere. The omega-3 family is a wide group, the most important and commonest of which are alpha-linoleic acid, stearidonic acid, eicosatetraenoic acid, eicosapentaenoic acid, and docosahexaenoic asit. On the orther side, vitamin E is one of the most important antioxidants in humans. Vitamin E forms two main families, alpha, beta, gamma and delta tocopherol, and tocotrienol. For this study, fig seeds separated and oils obtained by cold press from the seeds of Ficus carica has been analyzed. Obtained oil acid content was analyzed by the gas chromatography with flame-ionization detection method. The High-Performance Chromatography Fluorescence Detector (HPLC-FLD) method was used to measure levels of vitamin E tocopherol. According to the results of the analysis, Ficus carica seed oil was seen to be rich in linolenic acid (omega-3, 40,25%), linoleic acid (omega-6, 31,28%), and oleic acid (omega-9, 17,0%) and it contained smaller amounts of palmitic acid, and other oils in trace amounts. Aflatoxin was not detected in the obteined seed oil. Ficuscarica seed oil was found to have a high content of gamma tocopherol proportion (4090,70 ± 383,30 mg/kg) is compared with that of other edible oil sources.

Ionogel sorbent coatings for determining organophosphorus and pyrethroid insecticides in water and fresh juice samples by headspace-solid phase microextraction

The sol–gel method yielded three different ionogel sorbent coatings that were obtained based on a silica material containing ionic liquids (ILs) immobilized in its pores. Two ILs, triethylsulfonium bis(trifluoromethylsulfonyl)imide [Set3][TFSI] and 1-butyl-1-methylpiperidinium bis(trifluoromethylsulfonyl)imide [C4C1Pip][TFSI], as well as their equimolar mixture [Set3/C4C1Pip], were used to obtain ionogel fibers. The developed sorbents were applied to extract six different insecticides from liquid samples. The crucial extraction parameters of headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography with flame ionization detection (GC-FID) method were optimized with a central composite design. The ionogel fibers demonstrated higher selectivity for extracting the analyzed insecticides compared with commercially available fibers. The calculated values of the enrichment factor were in the ranges of 41,400–106,100 for [Set3], 110,600–170,500 for [C4C1Pip], and 76,800–121,100 for [Set3/C4C1Pip]. The [Set3/C4C1Pip] ionogel fiber, demonstrated the highest selectivity for extraction the insecticides. Regarding this coating, the limit of detection in the range of 0.02–0.95 μg L−1, coefficient of determination, which were <0.9690, and a 2.1 %–6.5 % repeatability of the method were achieved. Finally, the obtained ionogel fibers were utilized to determine insecticides in fresh apple and carrot juices.

Development and validation of a gas chromatography with a flame ionization detector method for quantitative analysis of four major fatty acids extracted shark liver oil

Context: The shark liver of the species Ginglimostoma cirratun, Carcharhinus longimanus, and Carcharhinus falciformis, captured in the north-central coast of Cuba are a source of oil, whose content of major fatty acids could be used in its quality control. Aims: To develop a simple and robust gas chromatography with a flame ionization detector (GC-FID) method that is suitable for routine analysis of four major fatty acids extracted shark liver oil. Methods: Four major fatty acid content in shark liver oil pool of species Ginglimostoma cirratun, Carcharhinus longimanus, and Carcharhinus falciformis, was analyzed through the gas chromatography with a GC-FID. The fatty acids were analyzed as methyl esters derivatives, using 5% aqueous sulfuric acid in methanol. The method was validated in terms of linearity, precision, accuracy, specificity and limit of detection and quantitation. Results: Under the optimum analytical conditions, the analysis revealed that each target component was well separated with satisfactory recoveries and reproducibility. The method linearity was found to be high with good determination coefficient values for all target components. The evaluation of the matrix effect, demonstrated, that there is not interference from substances other than analysis. The method was also found to be accurate, precise and reproducible and it was applied to the quantitative determination of the fatty acid content in shark liver oil pool; oleic acid was the most abundant fatty acid (22.69%), followed by palmitic (18.85%), stearic (6.01 %) and myristic acid (0.40 %). Conclusions: The GC-FID developed method is reliable and suitable for determination of four major fatty acids in shark liver oil pool.

Simultaneous determination of terpenes and cannabidiol in hemp (Cannabis sativa L.) by fast gas chromatography with flame ionization detection.

Hemp (Cannabis sativa L.) has become widely used in several sectors due to the presence of various bioactive compounds such as terpenes and cannabidiol. In general, terpenes and cannabidiol content is determined separately, which is time consuming. Thus, a fast gas chromatography with flame ionization detection method was validated for simultaneous determination of both terpenes and cannabidiol in hemp. The method enabled a rapid detection of 29 different terpenes and cannabidiol within a total analysis time of 16min, with satisfactory sensitivity (limit of detection=0.03-0.27µg/mL, limit of quantitation=0.10-0.89µg/mL). The inter- and intraday precision (RSD) was<7.82 and<3.59%, respectively. Recoveries at two spiked concentration levels (low, 3.15µg/mL; high, 20.0µg/mL) were determined on both apical leaves (78.55-101.52%) and inflorescences (77.52-107.10%). The reproducibility (RSD) was<5.94 and<5.51% in apical leaves and inflorescences, respectively. The proposed and validated method is highly sensitive, robust, fast, and accurate for determination of the main terpenes and cannabidiol in hemp and could be routinely used for quality control.

Investigation of fugitive methane and gas collection efficiency in Halton landfill in Ontario, Canada.

Methane gas is one of the significant contributors to global warming. A large portion of methane emissions comes from landfills. Developing reliable measurement methods for methane emissions from landfill sites has become very important. In this paper, the surface emissions of methane gas are quantified using a portable probe having a flame ionization detector (FID), a method proven to be successful in landfill gas measurement. Surface methane emissions from two closed cells in the Halton landfill in Ontario, Canada, were measured using the FID method. By analyzing the emissions within the perimeter of the landfill, hotspots of gas leakage were identified. The closed cells in the Halton landfill are equipped with gas extraction system for flaring and energy recovery and a clay topsoil cover. Emission concentrations of fugitive methane were found to range from 0.1 to 63ppm. The largest emissions were detected in locations next to the leachate extraction manholes and malfunctioning gas extraction wells. The landfill gas balance showed that the landfill gas recovery efficiency was 44%, resulting in an average amount of fugitive methane from the landfill of 6124m3/day. The results of the study were used to determine the methane generation potential (Lo) for municipal solid waste to further calibrate the USEPA LandGEM model for Ontario landfills. The model was calibrated by actual methane emission measurement and recovery data. The calibrated Lo was found to be 70m3/t, which is lower than the estimated values in previous studies.

Rising above helium: A hydrogen carrier gas chromatography flame ionization detection (GC-FID) method for the simultaneous quantification of toxic alcohols and ethylene glycol in human plasma specimens

Here we validate a GC, Flame Ionization Detection (GC-FID), liquid injection method using hydrogen as a carrier gas combining analysis of toxic volatile alcohols (VA): methanol, ethanol, isopropanol, acetone, as well as glycols, ethylene glycol (EG) and propylene glycol (PG), in a single method. Methodology200 μL of calibrator, QC, or patient specimen were deproteinized with 400 μL of acetonitrile containing internal standards (10 mmol/L N-propyl alcohol for VA and 2.5 mmol/L 1,2-butanediol for glycols). GC-FID analysis using hydrogen carrier gas and nitrogen makeup gas utilized an Agilent 7890 system equipped with Agilent 7683 liquid autosampler on a 30 m × 530 μm RTX-200 fused silica column. Method validation included repeatability, recovery, carryover, linearity, lower limit of quantification (LLOQ), accuracy, selectivity and measurement uncertainty. ResultsThe 8.3 min from injection to injection reduced time of analysis by 45% over a previously reported method using Helium carrier gas with no loss in resolution. Within-run and Between-run variability were ≤1.4% and ≤6.8% respectively. Recovery was 100% within a 95% confidence interval. Carryover was negligible for all but EG. LLOQ was <1 mmol/L for all analytes. The upper range of linearity was 120 mmol/L for methanol, ethanol and isopropanol, 100 mmol/L for acetone and 50 mmol/L for EG. Analytes demonstrated acceptable accuracy and measurement uncertainty using College of American Pathologists (CAP) criteria. Toluene can cause a false positive EG, while benzene, xylene and 1,3 butanediol can cause false negative EG. ConclusionsConverting from Helium to Hydrogen carrier gas benefits patient care through a reduction in turnaround time and provides a cost savings to the laboratory.

Rapid fingerprinting technology of heavy oil spill by mid-infrared spectroscopy

ABSTRACT With the increase of unconventional oil production and transportation, the detection methods of light crude oil have been challenged. Mid-Infrared spectroscopy can reflect the functional group of the oil related samples, which has strong absorption signals with distinguishable peaks featured as a fast, economy, and robust technique. Nevertheless, the previous study and application of oil relevant samples, such as petroleum chemical industry online monitoring, are mainly based on Near-infrared spectroscopy. Recently, the rapid development of the spectral instrument manufacturing and the data analysis methods provides a more comprehensive technical support for the rapid and accurate identification of marine oil spill by Mid-infrared spectroscopy. In this paper, 10 crude oil samples were selected for infrared spectroscopy detection, and the results were analysed and compared with those of gas chromatography flame ionization detection method. The character information of the IR spectra and GC/FID chromatograms were extracted and classified both by principal component analysis and partial least squares regression. Under the condition of small sample size, the recognition accuracy was up to 100%. The results show that the mid-infrared method combined with chemometrics can be expected to achieve rapid, accurate and economical identification of heavy oil species.

Methods for one– and two–dimensional gas chromatography with flame ionization detection for identification of Mycobacterium tuberculosis in sputum

Two simplified methods based on manual thermally–assisted hydrolysis and methylation (THM) GC and GC × GC with flame ionization detection (FID) were developed for the detection of mycobacteria and Mycobacterium tuberculosis (MTB) in sputum. A central composite design was employed to optimize the THM derivatization conditions. For the detection of MTB the known mycobacterial markers tuberculostearic acid (TBSA) and hexacosanoic acid (C26), as well as three MTB specific markers, the mycocerosates, were evaluated. We found that the optimum conditions for THM release of TBSA and C26 differ from those for maximum release of the mycocerosates. Higher reagent volumes, higher temperatures and longer incubation increase the mycocerosates yield. Application of these conditions unfortunately resulted in unacceptable safety hazards. A GC × GC–FID method was developed that allowed accurate detection of mycocerosates even at poor conversion yields of the derivatization reaction. Using spiked sputum samples from non–TB patients, the detection limit of the method based on TBSA and C26 was found to be comparable to that of microscopy, i.e. 104–105 bacteria/mL sputum. To validate the new test, we compared the results we found for fifteen sputum samples from patients from South Africa suspected of having tuberculosis with those of culture, the gold standard method. Based on the presence of TBSA and C26, all eight microscopy and culture positive samples, and even two microscopy negative but culture positive samples were positive by THM–GC–FID. All five microscopy and culture negative sputum samples were also negative for THM–GC–FID, giving a specificity of 100%. Using GC × GC–FID we could detect mycocerosates, the specific markers for MTB in seven out of ten MTB culture positive sputum samples. The five culture negative cases were also negative for mycocerosates in manual THM–GC × GC–FID giving again 100% specificity. The results obtained indicate that the new methods hold great potential for the early diagnosis of TB in developing countries.

Generic gas chromatography flame ionization detection method using hydrogen as the carrier gas for the analysis of solvents in pharmaceuticals

Within the pharmaceutical industry, the determination of residual solvents by Gas Chromatography Flame Ionization Detection (GC-FID) is a highly utilized analytical test that often employs helium (He) as the carrier gas. However, many do not realize that helium is a non-renewable resource that will eventually become progressively more difficult to source. In recent years, analytical chemists are increasingly adopting hydrogen (H2) in place of helium for routine GC analysis. In this study, a simple and efficient generic/universal GC-FID method using H2 as the carrier gas has been developed with the capability of baseline resolution of over 30 of the most commonly used solvents in development and manufacturing with a method run time of less than eight minutes. The use of this method for the separation and analysis of solvents within a pharmaceutical manufacturing process is demonstrated with additional method validation data presented using five different diluents as a means to increase flexibility for the chromatographer. Furthermore, it is the recommendation of the authors that the current compendia for residual solvent analysis be updated to allow for hydrogen as a carrier gas. The similarity between He and H2 observed within this study supports the use of hydrogen as a suitable replacement for helium, and an update of the EU and USP compendia for residual solvent analysis should be made to reflect this.

Determination and Quantitation of Residual Solvents in Natural Food Ingredients Using a Static Headspace Gas Chromatography with Flame Ionization Detection and Mass Spectrometric Detection Method

The determination of residual solvents is critical for quality control in food production and manufacturing processes. A gas chromatographic and mass spectrometric detection (MSD) method was developed and validated to complement the static headspace flame ionization detection (FID) technique for identification, confirmation, and quantitation of solvent residues in botanicals, using Coffeeberry extract and pomegranate powder as test samples. Relative standard deviations (RSDs) of less than 12% were obtained for residual solvents in water and dimethyl sulfoxide. Coffeeberry extract supplemented with10 μg/g of Residual Solvents Class 3 Mix showed MSD and FID recoveries mainly of 91 to 121% and 77 to 110%, respectively, while those samples supplemented with 100 μg/g of Residual Solvents Class 3 Mix displayed MSD and FID recoveries of 105 to 123% and 87 to 112%, respectively. For pomegranate samples supplemented with 10 μg/g of Residual Solvents Class 3 Mix, MSD and FID recoveries of 95 to 124% and 72 to 151% were observed, respectively. Those samples supplemented with 100 μg/g of Residual Solvents Class 3 Mix exhibited MSD and FID recoveries of 109 to 135% and 97 to 127%, respectively. Thus, the developed procedure was demonstrated to be suitable for the analysis of residual solvents in natural food ingredients and is expected to find numerous industrial applications (e.g., process control and impurity detection in final products).

Extraction and Determination of Trace Amounts of p-Coumaric Acid in Vinegar, Carrot Juice, and Seed Extract from Silybum marianum (L.) Gaertn.

In this study, for the monitoring and quantification of p-coumaric acid (p-CA) in vinegar, carrot juice, and seed extract from the plant species Silybum marianum (L.) Gaertn, an efficient and low-cost analytical method has been applied. For this purpose, a dispersive liquid-liquid microextraction (DLLME) method, followed by UV-Vis spectrophotometric detection, was used. To form a cloudy solution, a binary mixture containing ethanol as a disperser solvent and chloroform as an extraction solvent was rapidly injected by syringe into a sample solution containing p-CA. After centrifugation, dilution of the obtained organic phase was done with the proper amount of ethanol, and the phase was transferred into a micro cell for subsequent measurement. Some effective parameters for the DLLME method, such as the volume of disperser solvent and extraction solvent, pH, and salt concentration were inspected by a 24 full factorial central composite design using design Export Software. Under the optimized conditions, linearity was between 10 and 150 ng/mL, and the LOD was 2.3 ng/mL. The results of the proposed method were similar to the obtained results using a GC with flame-ionization detection method.

Measuring NMHC and NMOG emissions from motor vehicles via FTIR spectroscopy

The determination of non-methane organic gases (NMOG) emissions according to United States Environmental Protection Agency (EPA) regulations is currently a multi-step process requiring separate measurement of various emissions components by a number of independent on-line and off-line techniques. The Fourier transform infrared spectroscopy (FTIR) method described in this paper records all required components using a single instrument. It gives data consistent with the regulatory method, greatly simplifies the process, and provides second by second time resolution. Non-methane hydrocarbons (NMHCs) are measured by identifying a group of hydrocarbons, including oxygenated species, that serve as a surrogate for this class, the members of which are dynamically included if they are present in the exhaust above predetermined threshold levels. This yields an FTIR equivalent measure of NMHC that correlates within 5% to the regulatory flame ionization detection (FID) method. NMOG is then determined per regulatory calculation solely from FTIR recorded emissions of NMHC, ethanol, acetaldehyde, and formaldehyde, yielding emission rates that also correlate within 5% with the reference method. Examples are presented to show how the resulting time resolved data benefit aftertreatment development for light duty vehicles.