Gas Chromatography-flame Ionization Detection Method Research Articles

Development and Validation of a GC-FID Method for the Quantitation of Δ 8-Tetrahydrocannabinol and Impurities Found in Synthetic Δ 8-Tetrahydrocannabinol and Vaping Products.

Concerns about health hazards associated with the consumption of trans-delta-8-tetrahydrocannabinol products were highlighted in public health advisories from the U. S. Food and Drug Administration and U. S. Centers for Disease Control and Prevention. Simple and rapid quantitative methods to determine trans-delta-8-tetrahydrocannabinol impurities are vital to analyze such products. In this study, a gas chromatography-flame ionization detection method was developed and validated for the determination of delta-8-tetrahydrocannabinol and some of its impurities (recently published) found in synthesized trans-delta-8-tetrahydrocannabinol raw material and included olivetol, cannabicitran, Δ 8-cis-iso-tetrahydrocannabinol, Δ 4-iso-tetrahydrocannabinol, iso-tetrahydrocannabifuran, cannabidiol, Δ 4,8-iso-tetrahydrocannabinol, Δ 8-iso-tetrahydrocannabinol, 4,8-epoxy-iso-tetrahydrocannabinol, trans-Δ 9-tetrahydrocannabinol, 8-hydroxy-iso-THC, 9α-hydroxyhexahydrocannabinol, and 9β-hydroxyhexahydrocannabinol. Validation of the method was assessed according to the International Council for Harmonization guidelines and confirmed linearity with R2 ≥ 0.99 for all the target analytes. The limit of detection and limit of quantitation were 1.5 and 5 µg/mL, respectively, except for olivetol, which had a limit of detection of 3 µg/mL and a limit of quantitation of 10 µg/mL. Method precision was calculated as % relative standard deviation and the values were less than 8.4 and 9.9% for the intraday precision and inter-day precision, respectively. The accuracy ranged from 85 to 118%. The method was then applied to the analysis of 21 commercially marketed vaping products claiming to contain delta-8-tetrahydrocannabinol. The products analyzed by this method have various levels of these impurities, with all products far exceeding the 0.3% of trans-Δ 9-tetrahydrocannabinol limit for hemp under the Agriculture Improvement Act of 2018. The developed gas chromatography-flame ionization detection method can be an important tool for monitoring delta-8-tetrahydrocannabinol impurities in commercial products.

Evaluation of extraction and entrapment efficiency of black seed oil-containing emulsion as a delivery system for thymoquinone

Black seed oil (BSO) or Nigella sativa contains numerous bioactive components, in which thymoquinone (TQ) becomes a functional key compound and serves as an analytical marker. With its non-polar characteristic, lipid-based delivery systems can be a solution to improve the solubility of BSO. Thus, it is necessary to have a valid basis for TQ quantification, especially in the emulsion as the delivery system of BSO. This study aimed to validate a Gas Chromatography-Flame Ionization Detector (GC-FID) method for quantifying TQ, and subsequently employ the method to evaluate TQ extraction from BSO and BSO-containing emulsion and determine the entrapment efficiency of the emulsion. The method indicated a linearity between 10 and 1280 µg/ml with detection and quantification limits of 13,59 and 41,19 µg/ml, respectively. The extraction of TQ with the sample:methanol ratio of 1:9 and 30-min centrifugation yielded the maximum TQ recovery from BSO and BSO-containing emulsion. The entrapment efficiency in emulsion reached 64,83% obtained with the density-changing centrifugation method. Overall, this validated GC-FID method demonstrated that the selected condition in the methanol extraction could effectively separate TQ from both BSO and its emulsion matrices and support the determination of the entrapment efficiency of the BSO-containing emulsion.

Quantitative Determination of Cannabis Terpenes Using Gas Chromatography-Flame Ionization Detector.

Background: Cannabis has a long history of being credited with centuries of healing powers for millennia. The cannabis plant is a rich source of cannabinoids and terpenes. Each cannabis chemovar exhibits a different flavor and aroma, which are determined by its terpene content. Methods: In this study, a gas chromatography-flame ionization detector method was developed and validated for the determination of the 10 major terpenes in the main three chemovars of Cannabis sativa L. with n-tridecane used as the internal standard following the standard addition method. The 10 major terpenes (monoterpenes and sesquiterpenes) are α-pinene, β-pinene, β-myrcene, limonene, terpinolene, linalool, α-terpineol, β-caryophyllene, α-humulene, and caryophyllene oxide. The method was validated according to Association of Official Analytical Chemists guidelines. Spike recovery studies for all terpenes were carried out on placebo cannabis material and indoor-growing high THC chemovar with authentic standards. Results: The method was linear over the calibration range of 1-100 μg/mL with r2>0.99 for all terpenes. The limit of detection and limit of quantification were calculated to be 0.3 and 1.0 μg/mL, respectively, for all terpenes. The accuracy (%recovery) at all levels ranged from 89% to 104% and 90% to 111% for placebo and indoor-growing high THC chemovar, respectively. The repeatability and intermediate precision of the method were evaluated by the quantification of target terpenes in the three different C. sativa chemovars, resulting in acceptable relative standard deviations (less than 10%). Conclusions: The developed method is simple, sensitive, reproducible, and suitable for the detection and quantification of monoterpenes and sesquiterpenes in C. sativa biomass.

Identification of residues in ethylene oxide sterilized hard gelatin capsule shells by gas chromatography-mass spectrometry and development of a simple gas chromatography-flame ionization detector method for the determination of residues

Four toxic residues in gelatin capsule shells after ethylene oxide (EO) sterilization were identified by gas chromatography-mass spectrometer (GC-MS) and they were ethylene oxide, 2-chloroethanol, acetaldehyde, and 1,4-dioxane. The generation pathway and mechanism of the 2-chloroethanol, acetaldehyde, and 1,4-dioxane were further investigated. Additionally, a simple and rapid gas chromatography-flame ionization detector (GC-FID) method was established and fully validation including specificity, linearity, sensitivity, and accuracy were conducted according to ICH Q2 (R1) guidelines. The results showed good linearities with coefficients (r) higher than 0.9999 for four analytes. The limits of detection (LODs) of four analytes were in the range of 0.025-1.0 μg·mL −1 and the limits of quantitation (LOQs) were in the range of 0.05-2.0 μg·mL −1 . The recoveries of four impurities were ranged from 83.0 % to 114.9 %. The repeatability and inter-day precisions were in the ranges of 0.7-3.3%. This validated GC-FID method provided an approach for capsule manufacturers to routinely monitor residues in gelatin capsule shells, design and optimize the storage time after sterilization and judge whether it can be released from the factory after sterilization. It can also be used for enterprises and regulatory bodies to routinely control the quality of hard gelatin capsule shells.

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.

In vivo quantification of polyhydroxybutyrate (PHB) in the alphaproteobacterial methanotroph, Methylocystis sp. Rockwell

Methane is a common industrial by-product that can be used as feedstock for production of the biopolymer polyhydroxybutyrate (PHB) by alphaproteobacterial methanotrophs. In vivo assessment of PHB production would shed light on the biosynthesis process and guide design of improved production strategies, but it is currently difficult to perform efficiently. In this study, the alphaproteobacterial methanotroph Methylocystis sp. Rockwell was grown on methane with three different nitrogen sources (ammonium, nitrate, and atmospheric nitrogen), and biomass samples were harvested at defined time points during lag, exponential, and stationary growth phases. PHB cell content was analyzed at these sampling points via a standard gas chromatography-flame ionization detector method, which requires hydrolysis of PHB and esterification of the resulting monomer under acidic conditions, and a novel, rapid, cost-effective approach based on fixation and staining of bacterial cells via Nile Blue A fluorescent dye enabling differential staining of cell membranes and intracellular PHB granules for single-cell analysis through fluorescence microscopy. Overall, the two PHB quantification approaches were in agreement at all stages of growth and in all three growing conditions tested. The PHB cell content was greatest with atmospheric nitrogen as a nitrogen source, followed by ammonium and nitrate. Under atmospheric nitrogen and ammonium conditions, PHB cell content decreased with growth progression, while under nitrate conditions PHB cell content remained unchanged in all growth phases. In addition to presenting a rapid, efficient method enabling in vivo quantification of PHB production, the present study highlights the impact of nitrogen source on PHB production by Methylocystis sp. Rockwell. KEY POINTS: • A novel fluorescence microscopy method to quantify PHB in single cells was developed • The microscopy method was validated by the derivation/gas chromatography method • Methylocystis sp. Rockwell synthesizes PHB granules without nutrient stress.

Development of methods for determining free fatty acid contents in red colored oils.

The online version contains supplementary material available at 10.1007/s10068-021-00964-2.

A gas chromatography-flame ionization detection method for direct and rapid determination of small molecule volatile organic compounds in aqueous phase.

It is still difficult to directly detect low content of volatile organic compounds (VOCs) in water samples by gas chromatography (GC) because when water is the only solvent, it would result in the instability and poor repeatability of peak retention time and peak shape. The adverse effects of water on direct GC analysis of VOCs cannot be significantly reduced or eliminated by simply changing the detection condition of GC. However, it was found that the addition of methanol in samples to a certain final proportion, such as 50 or 75% (v/v), could greatly reduce or eliminate the adverse effects of water. By using 75% (v/v) methanol as a solvent, the standard curves of ethanol, acetic acid, acetone, and isopropanol with correlation coefficient (R 2) over 0.99 were successfully plotted by gas chromatography-flame ionization detection (GC-FID) in a certain concentration range, respectively. The results showed that the retention time and peak shape stability of ethanol, acetic acid, acetone, and isopropanol in aqueous solution were greatly improved by the addition of methanol to final concertation of 75% (v/v). To verify the practical application potential of this method, the method was applied to the detection of components in isopropanol fermentation wastewater. The results showed that the method has well applicability and reliability. The key points in the application of this method were also summarized. This GC analysis method would have a wider and better application prospect in the detection of water-soluble organic matters.

An accelerated solvent extraction and gas chromatography-flame ionization detector method to rapidly determining and assessing total petroleum hydrocarbon contamination in soil from Fushan oilfield, China.

A high-efficient method for determining the total petroleum hydrocarbon (TPH) was established by gas chromatography-flame ionization detection, coupled with an efficient 10m short chromatographic column; the analyzing period was narrowed to 5mins. The limits of detection of the methodincluded 1.47, 4.02, and 0.69mg/kg, and the corresponding limits of quantification reached 4.45, 12.2, and 2.10mg/kg for the three fractions C10-C16, C17-C34, and C35-C40, respectively. The method was employed to real samples to achieve the routine environmental monitoring of TPH in polluted sites from Fushan oilfield, China. As revealed from the analysis of 30 soil samples in the study area, a wide range of TPH concentrations were achieved: 61.6-7300mg/kg (average, 1055mg/kg) for ΣC10-C16, 438-14,280mg/kg (average, 4544mg/kg) for ΣC17-C34, 25.4-638mg/kg (average, 250mg/kg) for ΣC35-C40, and 617-15,348 (average, 5848mg/kg) for ΣC10-C40, respectively. According to the Nemerow integrated pollution index, the Fushan oilfield has been slightly polluted by TPH. As suggested from the distribution of TPH concentrations, the main sources of TPH in soil samples of Fushan oilfield included oil spills during temporary storage, transportation, and oil exploitation. Adopting the developed method to delve into oilfield soil samples further verifies the effectiveness of the method, indicating that the method can well meet the growing demand of regulatory guidelines for related risk assessment and environmental monitoring and remediation strategy formulation.

Gas chromatographic determination of trace carbon monoxide and carbon dioxide in sulfur hexafluoride and its application to probing potential breakdown of high-voltage circuit breaker

A reliable gas chromatography-flame ionization detector (GC-FID) method was developed for the accurate determination of trace CO and CO2 in high concentration of SF6. Using a combination of dual Porapak Q chromatographic columns with valve switching, SF6 was separated from the tested samples and blown out of the detection system, with the aim of ruling out the possibility of conversion column poisoning. Meanwhile, CO and CO2 were on-line separated and subsequently converted to CH4 in the presence of a nickel catalyst to increase the sensitivity for the determination of carbon-borne gases. The results showed that neither gas interfered with the determination of the other. Satisfactory linearities were achieved in the range 2-500 μL/L for both CO and CO2, with highly accurate and reproducible determination (RSD<2%). The developed GC-FID method is applicable to the determination of gases lodged in high-voltage circuit breakers toward the analysis of trace CO and CO2, thus providing a tool for probing the potential breakdown of SF6-insulated equipment.

ANALYSIS OF BISPHENOL A IN INDONESIAN CANNED FOOD BY GAS CHROMATOGRAPHY

Objective: This study aimed to design and optimize a gas chromatography-flame ionization detection (GC-FID) method to determine the bisphenol A (BPA)content in Indonesian canned food samples.Methods: GC with Hewlett-Packard-1 capillary columns (length, 30 m; inside diameter, 0.25 mm; and film thickness, 0.25 μm) was used with a columntemperature of 150°C that was programmed to increase by 10°C/min to 260°C. Injector and detector temperatures were 280 and 300°C, respectively,the gas flow rate was 1.0 mL/min, and injection volume was 3.0 μL. Three types of canned food samples were prepared by ethyl acetate extraction andstored under four different conditions (4–8°C, 25–30°C, 40°C for 30 min, and 40°C for 60 min) to determine BPA migration levels.Results: Method validation (system compatibility, selectivity, calibration curve linearity, accuracy, and precision) was acceptable for BPAconcentrations ranging from 2 to 15 μg/mL, with a coefficient of correlation of 0.99983. The limits of detection and quantitation were 0.287 and0.956 μg/mL, respectively. Only one canned food sample type (Group A) showed BPA contamination under all storage conditions and exceeded therecommended guidelines for daily ingestion.Conclusion: The optimized GC-FID method was selective and relatively sensitive in the detection and quantitation of BPA. Furthermore, higherstorage temperatures and durations increased the level of BPA migration into food.

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.

A High-Throughput Method for the Analysis of Erythrocyte Fatty Acids and the Omega-3 Index.

Omega-3 long-chain polyunsaturated fatty acids (n-3 LCPUFA) have several health benefits. In particular, low n-3 LCPUFA status is associated with cardiovascular disease (CVD) and led to the development of the omega-3 index that is the proportion of eicosapentaenoic acid and docosahexaenoic acid in the erythrocyte membranes, as a marker of CVD risk. Most methods used to measure the omega-3 index are laborious and time consuming. Therefore, the aim of this study was to develop a high-throughput method for the extraction and measurement of erythrocyte fatty acids and the omega-3 index. For sample extraction and quantification, two methods were used; a single-step extraction, degradation, and derivatization method by Lepage and Roy, followed by gas chromatography flame ionization detection (GC-FID), which is commonly used and a high-throughput method using an automated methyl tert-butyl ether extraction followed by electrospray ionization mass spectrometry. Both methods were first applied to the analysis of known concentrations of synthetic phospholipid (PL) mixtures to determine recovery and precision prior to their application in the analysis of human erythrocytes. The range of recoveries over five synthetic PL mixtures were 86.4-108.9% and the coefficient of variation was <10% (within-run) and ≤15.2% (between-run). Both methods showed high correlation (R = 0.993) for the omega-3 index and there was no systematic bias in the detection of omega-3 index using either method. The new high-throughput method described here offers considerable advantages in terms of simplicity and throughput compared to the GC-FID method and provides additional information on molecular PL concentrations.

Optimization and comparison of GC-FID and HPLC-ELSD methods for determination of lauric acid, mono-, di-, and trilaurins in modified coconut oil

Modified coconut oil (MCO) obtained from the glycerolysis of virgin coconut oil (VCO) and glycerol under various conditions should have different amounts of bioactive fatty acids (FAs) and acylglycerols (AGs). Methods were developed to analyze lauric acid (LA), monolaurin (ML), dilaurin (DL), and trilaurin (TL) in MCO samples using gas chromatography - flame ionization detector (GC-FID) and high performance liquid chromatography - evaporative light scattering detector (HPLC-ELSD). The purpose of this research is to optimize and compare GC-FID and HPLC-ELSD methods for determination of LA, ML, DL, and TL in MCO samples. All the standard curves exhibited good linearity (R2 ≥ 0.9995), except for that of LA analyzed by HPLC-ELSD (R2 = 0.9971). The limits of detection (LODs) and quantification (LOQs) were found to be in the range of 0.033–0.260 mg/ml and 0.099–0.789 mg/ml for the GC-FID method and 0.040–0.421 mg/ml and 0.122–1.277 mg/ml for the HPLC-ELSD method, respectively. The GC-FID method (LOD ≤ 0.033 mg/ml) was more sensitive than HPLC-ELSD method (LOD ≤ 0.421 mg/ml) and showed satisfactory recoveries for LA analysis while HPLC-ELSD method (LOD ≤ 0.040 mg/ml) was more sensitive than GC-FID method (LOD ≤ 0.260 mg/ml) and exhibited acceptable recoveries for TL analysis. Both methods were applied to determine the MCO samples produced under varied conditions for glycerolysis. The results revealed that the developed GC-FID method is suitable for the quantification of LA, ML, and DL while the developed HPLC-ELSD method is appropriate for the determination of ML, DL, and TL. Both developed GC–FID and HPLC–ELSD methods produced reproducible results for the determination of LA, ML, DL, and TL in MCO samples.

Generic gas chromatography-flame ionization detection method for quantitation of volatile amines in pharmaceutical drugs and synthetic intermediates

Volatile amines are among the most frequently used chemicals in organic and pharmaceutical chemistry. Synthetic route optimization often involves the evaluation of several different amines requiring the development and validation of analytical methods for quantitation of residual amine levels. Herein, a simple and fast generic GC-FID method on an Agilent J&W CP-Volamine capillary column (using either He or H2 as the carrier gas) capable of separating over 25 volatile amines and other basic polar species commonly used in pharmaceutical chemistry workflows is described. This 16min method is successfully applied to the analysis and quantitation of volatile amines in a variety of pharmaceutically-related drugs and synthetic intermediates. Method validation experiments showed excellent analytical performance in linearity, recovery, repeatability, and limit of quantitation and detection. In addition, diverse examples for the application of this method to the simultaneous determination of other amine-related chemicals in reaction mixtures are illustrated, thereby indicating that these GC-FID method conditions can be effectively used as starting point during method development for the analysis of other basic polar species beyond the validated list of amines described in this study.

Production of Farmstead Lactose-Free Pecorino di Osilo and Ricotta Cheeses from Sheep's Milk.

The present work was aimed to define and validate farmstead production of lactose-free Pecorino di Osilo cheese, fresh ricotta cheese, and salted and smoked ricotta cheese (Ricotta mustia). The enzymatic activity of the commercial preparation containing lactase (1.1 g/mL), preliminarily tested using a spectrophotometric titration, showed activity equal to 4950±40 neutral lactase unit/g. The amount of lactase required to obtain the lactose-free milk was then established in triplicate laboratory trials, by adding the enzyme at concentrations of 0.7, 0.9 and 1.1 g/L in flasks containing 160 mL of raw sheep’s milk. Samples were incubated under conditions expected during milk storage and cheese-making. The residual lactose content in milk was determined by enzymatic method. The addition of lactase at concentration of 1.1 g/L of milk reduced the lactose concentration below the limit of detection (LOD) of 0.06 g/L. The procedure was validated at a dairy farm, using three different batches of bulk raw sheep’s lactose-free milk that were transformed into Pecorino di Osilo cheese. The resulting whey was used to produce fresh ricotta and Ricotta mustia cheese. Raw milk and whey samples were always below lactose detection limit. The residual lactose was measured in Pecorino di Osilo cheese, after 24 hours and 30 days from production; in fresh ricotta cheese, after 48 hours; in Ricotta mustia cheese after 7 days. The determination of lactose content in cheese samples was conducted by a gas chromatography-flame ionization detection method, which showed a LOD and limit of quantification respectively of 1.8 and 5.6 mg/kg for cheese, and 1.35 and 4.2 mg/kg for both ricotta cheeses. The lactose concentration was always below the relevant LOD values in all samples. The mean concentration of galactose and glucose were respectively 13,000±2000 and 11,000±2000 mg/kg in fresh Pecorino di Osilo, 1100±300 and 1200±300 mg/kg in fresh ricotta, and 950±400 and 750±250 mg/kg in Ricotta mustia. The results of the present study showed that the production of farmstead lactose-free Pecorino di Osilo cheese and ricotta cheeses from raw sheep’s milk is easily achievable. The main issue for farmstead production of artisanal lactose-free products is the implementation of permanent procedures based on hazard-analysis and critical control principles aimed at guaranteeing the effectiveness of the process and at acquiring analytical evidences to demonstrate the fulfilment of law requirements for labelling.

Quantification of Triacylglycerol Molecular Species in Edible Fats and Oils by Gas Chromatography-Flame Ionization Detector Using Correction Factors.

In the present study, the resolution parameters and correction factors (CFs) of triacylglycerol (TAG) standards were estimated by gas chromatography-flame ionization detector (GC-FID) to achieve the precise quantification of the TAG composition in edible fats and oils. Forty seven TAG standards comprising capric acid, lauric acid, myristic acid, pentadecanoic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, linoleic acid, and/or linolenic acid were analyzed, and the CFs of these TAGs were obtained against tripentadecanoyl glycerol as the internal standard. The capillary column was Ultra ALLOY+-65 (30 m × 0.25 mm i.d., 0.10 μm thickness) and the column temperature was programmed to rise from 250°C to 360°C at 4°C/min and then hold for 25 min. The limit of detection (LOD) and limit of quantification (LOQ) values of the TAG standards were > 0.10 mg and > 0.32 mg per 100 mg fat and oil, respectively, except for LnLnLn, and the LOD and LOQ values of LnLnLn were 0.55 mg and 1.84 mg per 100 mg fat and oil, respectively. The CFs of TAG standards decreased with increasing total acyl carbon number and degree of desaturation of TAG molecules. Also, there were no remarkable differences in the CFs between TAG positional isomers such as 1-palmitoyl-2-oleoyl-3-stearoyl-rac-glycerol, 1-stearoyl-2-palmitoyl-3-oleoyl-rac-glycerol, and 1-palmitoyl-2-stearoyl-3-oleoyl-rac-glycerol, which cannot be separated by GC-FID. Furthermore, this method was able to predict the CFs of heterogeneous (AAB- and ABC-type) TAGs from the CFs of homogenous (AAA-, BBB-, and CCC-type) TAGs. In addition, the TAG composition in cocoa butter, palm oil, and canola oil was determined using CFs, and the results were found to be in good agreement with those reported in the literature. Therefore, the GC-FID method using CFs can be successfully used for the quantification of TAG molecular species in natural fats and oils.

Development of a poly(ethylene glycol)–graphene oxide sol–gel coating for solid-phase microextraction of aromatic amines in water samples with a gas chromatography-flame ionization detector method

The wrinkled structure of a PEG–GO sol–gel coating increases the surface area on the fiber, the speeds of extraction and desorption steps and sample capacity.

Development and Validation of a Gas Chromatography–Flame Ionization Detection Method for the Determination of Epoxy Fatty Acids in Food Matrices

A reliable and suitable method for the determination of epoxy fatty acids in various food matrices based on the Bligh and Dyer lipid extraction procedure was developed and validated. The method involves the use of a methylated epoxy fatty acid as internal standard (IS), extraction of the analytes from the matrices followed by room temperature methylation, a three-step solid phase extraction (SPE) separation of the fatty acid methyl esters (FAMEs), and detection with gas chromatography-flame ionization detection (GC-FID). The method was validated in four different food matrices chosen as model systems, namely, vegetable oils, unprocessed pork, fried potato crisps, and infant formula. The extraction technique allows the method to be applied for routine analysis of a large amount of samples. Intraday repeatability ranged from 1 to 19%, and interday reproducibility ranged from 2 to 9%. The limit of quantification (LOQ) ranged from 3.32 to 20.47 μg g(-1) of sample with recoveries ranging from 94 to 115%. The results verify the accuracy and reproducibility of the analytical technique and its ability to provide reliable quantification of epoxy fatty acids. Finally, levels of epoxy fatty acids in several food products on the Belgian market were screened and are presented.

Development and validation of a gas chromatography–flame ionization detection method for quantifying sucrose in equine serum

A simple and accurate method for quantifying sucrose in equine serum that can be applied to sucrose permeability testing in the horse was developed and validated using gas chromatography with flame ionization detection. The assay provided an acceptable degree of linearity, accuracy, and precision at concentrations of sucrose as low as 2.34 μmol/l and as high as 20.45 μmol/l. Percentage recovery of sucrose from serum ranged from 89% to 102%; repeatability and intermediate precision (relative standard deviation) ranged from 3.6% to 6.7% and 4.1% to 9.3%, respectively. The limit of detection was 0.73 μmol/l. No interfering peaks were observed except lactose, which gave 2 peaks, one of which overlapped partially with sucrose. To evaluate the suitability of the method for quantifying sucrose in serum samples from horses with naturally occurring gastric ulceration, 10 horses with and without naturally occurring gastric ulceration were subjected to sucrose permeability testing. All horses demonstrated an increase in serum sucrose concentration over time following oral administration of sucrose; however, the increase from baseline was significant for horses with gastric ulceration at 45 min (P = 0.0082) and 90 min (P = 0.0082) when compared with healthy horses. It was concluded that gas chromatography with flame ionization detection is a valid method for quantifying sucrose in equine serum and can be applied directly to the analysis of sucrose in equine serum as part of a larger validation study aimed at developing a blood test for the diagnosis of gastric ulcers in horses.