Simple Gas Chromatography Research Articles

Simultaneous determination of methanol, ethanol, and formic acid in human serum by HSGC-MS: Method development, validation, and application

The concurrent assessment of methanol, ethanol, and formic acid is imperative for accurate clinical toxicology diagnosis in cases of methanol poisoning. Here, we reported a very simple and reliable headspace gas chromatography coupled with mass spectrometry (HSGC-MS) method for simultaneous quantitative determination of methanol, ethanol and formic acid in blood samples. The derivatization variables for formic acid were optimized. The method exhibits high sensitivity, good selectivity and effective separation factor for methanol (6.51 min), ethanol (8.29 min), and formic acid (11.41 min). The method demonstrates excellent reproducibility and accuracy. The limit of detection (LOD) and the limit of quantification (LOQ) were determined to be 3.14–5.83 μg/mL and 10.47–19.34 μg/mL, respectively. Finally, this method was successfully used for measuring the levels of methanol, ethanol, and formic acid in the serum of patients involved in actual methanol poisoning incidents.

A High-Throughput Experimental Approach to Screening Gas Sorption by Liquids and Solids.

High-precision measurement of gas uptake from single or mixed feeds in solid and liquid sorbents traditionally requires time-consuming experimental procedures and/or complex and costly equipment. A simple and cost-effective headspace gas chromatography (HS-GC) approach for the fast, universal experimental screening of sorbents for gas uptake and/or determination of their real gas separation selectivity has been developed and is demonstrated for pressures up to 2500 mbar and temperatures above 30 °C. This method allows screening of solids and both volatile and nonvolatile liquid materials, physisorbents, and chemisorbents using both single and mixed permanent gases that can include CO2, CH4, H2, and NH3, for gas uptakes as low as 0.04 mmol or 1.8 mg of CO2. We estimate that this method allows for the screening of at least 30-96 sorbents (in triplicate) or 90-264 sorbents (singles) per day, representing at least a 90-3000 times reduction in the time required for equivalent analysis.

Application of gas chromatography in the analysis of phytocannabinoids: An update (2020-2023).

Cannabinoids are a group of compounds that bind to cannabinoid receptors. They possess pharmacological properties like that of the plant Cannabis sativa. Gas chromatography (GC) is one of the popular chromatographic techniques that has been routinely used in the analysis of cannabinoids in different matrices. The article aims to review the literature on the application of GC-based analytical methods for the analysis of phytocannabinoids published during the period from January 2020 to August 2023. A thorough literature search was conducted using different databases, like Web of Knowledge, PubMed, Google Scholar, and other relevant published materials including published books. The keywords used, in various combinations, with cannabinoids being present in all combinations, in the search were cannabinoids, Cannabis sativa, marijuana, analysis, GC, quantitative, qualitative, and quality control. From the search results, only the publications that incorporate the GC analysis of phytocannabinoids were reviewed, and papers on synthetic cannabinoids were excluded. Since the publication of the review article on GC analysis of phytocannabinoids in early 2020, several GC-based methods for the analysis of phytocannabinoids have appeared in the literature. While simple 1D GC-mass spectrometry (MS) and GC-flame ionisation detector (FID) methods are still quite common in phytocannabinoids analysis, 2D GC-MS and GC-MS/MS are increasingly becoming popular, as these techniques offer more useful data for identification and quantification of phytocannabinoids in various matrices. The use of automation in sample preparation and the utilisation of mathematical and computational models for optimisation of different protocols have become a norm in phytocannabinoids analysis. Pre-analyses have been found to incorporate different derivatisation techniques and environmentally friendly extraction protocols. GC-based analysis of phytocannabinoids, especially using GC-MS, remains one of the most preferred methods for the analysis of these compounds. New derivatisation methods, ionisation techniques, mathematical models, and computational approaches for method optimisation have been introduced.

Development of a gas chromatography system coupled to a metal-oxide semiconductor (MOS) sensor, with compensation of the temperature effects on the column for the measurement of ethene

Abstract. A possible way to reduce the size and complexity of common gas chromatography (GC) systems is the economization of the column temperature regulation system. To this end, a temperature compensation method was developed and validated on a benchtop GC-PDD (pulsed discharge detector) with ethene. An in-house-developed algorithm correlates the retention index of a test gas to the retention index of a previously selected reference gas. To investigate further methods of cost reduction, commercial gas sensors were tested as cheap, sensitive, and versatile detectors. Therefore, CO2 was chosen as a naturally occurring reference gas, while ethene was chosen as a maturity marker for climacteric fruits and hence as a test gas. A demonstrator, consisting of a simple syringe injection system, a PLOT (porous layer open tubular) column boxed in a polystyrene-foam housing, a commercial MOS (metal-oxide semiconductor) sensor for the test gas, and a CO2-specific IR (infrared) sensor, was used to set up a simple GC system and to apply this method on test measurements. Sorption parameters for ethene and CO2 were determined via a van 't Hoff plot, where the entropy S was −11.982 J mol−1 K−1 ΔSEthene0 and 1.351 J mol−1 K−1 ΔSCarbondioxide0, and the enthalpy H was −20.622 kJ mol−1 ΔHEthene0 and −14.792 kJ mol−1 ΔHCarbondioxide0, respectively. Ethene (100 ppm) measurements revealed a system-specific correction term of 0.652 min. Further measurements of ethene and interfering gases revealed a mean retention time for ethene of 3.093 min; the mean predicted retention time is 3.099 min. The demonstrator was able to identify the test gas, ethene, as a function of the reference gas, CO2, in a first approach, without a column heating system and in a gas mixture by applying a temperature compensation algorithm and a system-specific holdup time correction term.

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.

GC-FID Quantification of N, N-Dimethyl Aminopropyl Chloride, a Genotoxic Impurity, in Imipramine Hydrochloride and Clomipramine Hydrochloride

Background: Early antidepressant Active Pharmaceutical Ingredients (API) like Imipramine hydrochloride and Clomipramine hydrochloride have not been assessed for Genotoxic Impurities (GTI) as per ICHM7. Objective: The main aim of the study was to develop a new simple and sensitive method for the determination of genotoxic impurities in Imipramine hydrochloride and Clomipramine hydrochloride active pharmaceuticals ingrediens. Methods: A simple, selective, and sensitive gas chromatography (GC) liquid injector method was developed for the quantitative determination of N, N-Dimethyl amino propyl chloride (DAPC) in API s. This method provided an excellent sensitivity and a typical target analyte level of 4.0 ppm. The DPAC content in the sample was analyzed on ZB-624, 30m x 0.53mm x 3.0μm column interfaced with a flame ionization detector (FID). The developed method was validated as per ICH guidelines. Results: The validated method showed good linearity over the concentration range of LOQ to 120% (1.18ppm to 4.8ppm) with a correlation coefficient of 0.9986. Limit of detection (LOD) and limit of quantitation (LOQ) were found to be 0.36 ppm and 1.18 ppm, respectively. This method showed high sample recovery (>90.0%). Conclusion: The developed method was a simple and sensitive gas chromatography liquid injector method. This method was validated as per ICH guidelines and could be very useful for the determination of a potential genotoxic impurity (DAPC) in imipramine hydrochloride and clomipramine hydrochloride active drug substance quality checking and ensuring safety of the patients.

Development and Validation of a Single Step GC/MS Method for the Determination of 41 Drugs and Drugs of Abuse in Postmortem Blood

A toxicology laboratory often receives a high number of samples from cases (autopsies or clinical) that may require the quick delivery of trustworthy, accurate results. Thus, there is a great need for a fast and reliable method that is capable of identifying and determining a large number of drugs and drugs of abuse in biological matrices, and especially in blood. In the present study, we describe the development of a fast and simple gas chromatography–mass spectrometry (GC-MS) method for the determination of 41 drugs and drugs of abuse (DOA) in blood. Sample pre-treatment by alkaline liquid–liquid extraction (LLE) was studied through the utilization of different solvents and solvent-to-sample ratios (v/v), which aimed to achieve a greater extraction efficiency and detection sensitivity with a decreased need for large sample volumes. Butyl acetate with a sample-to-solvent ratio of 4:1 (1 mL blood: 0.25 mL butyl acetate) was the most efficient. The method was validated for all analytes, and the evaluation parameters were within the acceptance criteria. The coefficient of determination (R2) was between 0.9934 and 1, the limits of detection (LODs) ranged between 1 ng/mL and 113 ng/mL, and the limits of quantification (LOQs) were between 4 ng/mL and 375 ng/mL for all analytes. The determinations were accurate (accuracy% from 84% to 114%) and precise (RSD% from 0.66% to 14.8% for low concentrations). Deconvolution Reporting Software (DRS) for GC-MS was optimized and applied for data analysis to enhance the identification potential, thereby avoiding false identifications (false positives) and increased productivity. The NIST Automated Mass Spectral Deconvolution and Identification Software (AMDIS) and the analytical utility Retention Time Lock (RTL) Database Library assisted in data evaluation. The method was applied to 89 postmortem cases (history of mental disorders and use of psychiatric pharmaceuticals) in which diazepam (0.13 to 4.34 μg/mL), citalopram (0.04 to 0.24 μg/mL), alprazolam (0.01 to 0.12 μg/mL), olanzapine (0.009 to 0.083 μg/mL), mirtazapine (0.01 to 0.33 μg/mL), venlafaxine (0.006 to 0.92 μg/mL), haloperidol (0.007 to 0.13 μg/mL), and zolpidem (0.01 to 0.16 μg/mL) were successfully quantitated.

Detection of volatile sulfur compounds (VSCs) in exhaled breath as a potential diagnostic method for oral squamous cell carcinoma

BackgroundOral squamous cell carcinoma causes a significant proportion of global cancer morbidity and mortality. The aim of this study is to investigate whether the exhaled breath test can be a new, non-invasive, and effective method for diagnosing oral squamous cell carcinoma.MethodsA comparative analysis of exhaled breath between patients with oral squamous cell carcinoma (OSCC) and healthy controls (HC) was performed with the Twin Breasor II™, a simple gas chromatography system.ResultsBoth hydrogen sulfide (H2S) and methyl mercaptan (Ch3SH) were significantly higher in the OSCC group than in the HC group. The total sulfur concentration was also higher in the OSCC group, but there was no significant difference in the ratio of Ch3SH to H2S between the two groups. Using logistic regression, we constructed a new variable with an area under the curve (AUC) of 0.740, 68.0% sensitivity, and 72.0% specificity.ConclusionsExhaled gas analysis via simple gas chromatography can potentially serve as an accessory non-invasive method for OSCC diagnosis.

Development and validation of a method for determining d-limonene and its oxidation products in vegetables and soil using GC–MS

A simple, rapid and effective gas chromatography–mass spectrometry method was developed for the simultaneous determination of d-limonene and its oxidation products in some vegetables and soils. Using the quick, easy, cheap, effective, rugged and safe (QuEChERS) method, the sample was extracted with n-hexane, purified with octadecylsilane (C18) and graphitized carbon black (GCB), and detected using gas chromatography-quadrupole mass spectrometry. The linear correlation coefficients of all analytes in the nine matrices were good (R2 > 0.995). At levels of 50, 100, and 1000 μg kg−1, the average recoveries ranged from 71.2 to 114.5%, while intra-day and inter-day precision were below 13.4%. The limits of detection (LODs) and the limits of quantification (LOQs) in all matrices for d-limonene and its five oxidation products were 1–16 and 4–48 μg kg−1, respectively. The residual levels of d-limonene can be well described by first-order kinetics. Dissipation in soil was microbially dominated, with half-lives of 1.95–2.84 days in the three soils and no residue in tomatoes. Its oxidation products were converted in soil mainly by microorganisms, with more trans-isomer production compared to cis-isomer. Moreover, no d-limonene residue was detected in tomatoes, and the persistence of d-limonene in soil was limited. The results of this study can provide data to understand the fate of d-limonene in tomato and soil and for further study its suitability as an environmentally friendly agrochemical.

GC-MS Method for Quantification and Pharmacokinetic Study of Four Volatile Compounds in Rat Plasma after Oral Administration of Commiphora myrrh (Nees) Engl. Resin and In Vitro Cytotoxic Evaluation

A rapid, simple, and sensitive gas chromatography–tandem mass spectrometry (GC–MS) method was established and validated for simultaneous determination of four volatile compounds, namely curzerene, methoxyfuranodiene, β-elemene, and α-pinene in rat plasma samples after oral administration of the resin extract of Commiphora myrrh using limonene as an internal standard (IS). Liquid-liquid extraction using hexane and ethyl acetate (1:1) mixture as an extracting agent was used for the samples extraction procedure. The GC–MS system was operated under selective ion monitoring (SIM) mode using Perkin Elmer Elite 5MS column (30 m × 0.25 mm × 0.25 µm film thickness). Specificity, linearity, precision, accuracy, extraction recovery, and stability were used to validate the developed method. The assay showed good linearity (r2 ≥ 0.998), and the lowest limits of quantification (LLOQ) were 3.97–21.38 ng/mL for the four analytes. This assay was successfully applied to pharmacokinetic studies of the four volatile compounds in rat plasma. The antiproliferative activity of these volatile compounds was evaluated against lung carcinoma (A549) and colon (LoVo) cell lines, were each compound caused variable inhibition on cells proliferation and methoxyfuranodiene exerted the strong antiproliferative activity against both cell line according to IC50 values.

A Rapid Method for the determination of Dehydrated alcohol (Ethanol) content in Clobetasol propionate foam by Non-polar Capillary Gas chromatography

Clobeatsol propionate foam is a topical class 1 corticosteroid used to treat itching and inflammatory arthritis on the skin occurred by allergic reactions, psoriasis and eczema. In the pharmaceutical aerosol products, Dehydrated alcohol (Ethanol) is the primary ingredient and its concentration level in the formulation composition plays a significant role in the regulation of aerosol rate, droplet shape and particle size. It can also act as solubilizer for active pharmaceutical ingredient, topical disinfectant and skin permeation enhancer. Hence accurate assay of Ethanol is a crucial quality control component. A simple and rapid gas chromatography method was developed to quantify Ethanol content in Clobetasol propionate foam drug product using fused silica glass tube non-polar capillary column (HP-5, 30 m, 0.53 mm, 1.5 µm). Ethanol in the sample was diluted with methanol after adding suitable amount of internal standard, the isopropyl alcohol solution.The developed method is precise, linear and accurate in the range of 5 mg/mL to 15 mg/mL of nominal concentration of ethanol i.e. 10 mg/mL . The presented method has an advantage of a very quick gas chromatographic separation (less than 16 min) and therefore is highly suitable for in-process and stability analysis of Ethanol content in Clobetasol propionate foam drug product.

Establishment and Validation of a GC-MS/MS Method for the Quantification of Penicillin G Residues in Poultry Eggs.

A simple and sensitive gas chromatography–tandem mass spectrometry (GC–MS/MS) method was established for the quantitative screening of penicillin G residues in chicken and duck eggs (whole egg, yolk and albumen). The analyte was separated on a TG-1MS capillary column (30.0 m × 0.25 mm i.d., 0.25 μm) with an external calibration method and electron impact (EI) ionization. Samples were pretreated using an accelerated solvent extraction (ASE) procedure followed by solid-phase extraction (SPE) on HLB cartridges (60 mg/3 mL). The derivative, which was safer and easier to store than penicillin G, was obtained by reacting trimethylsilyl diazomethane (TMSD) with penicillin G. The method was validated by the following parameters: linearity, accuracy, precision, limit of detection (LOD) and limit of quantification (LOQ). The matrix-matched calibration curves had good linearity (R2 ≥ 0.9994) within the concentration range of LOQ–200.0 µg/kg for penicillin G in the sample matrices. In the same concentration range, the accuracy, in terms of recovery, was 80.31–94.50%; the relative standard deviation (RSD), intra-day RSD and inter-day RSD ranged from 1.24 to 3.44%, 2.13 to 4.82% and 2.74 to 6.13%, respectively. The LODs and LOQs of penicillin G in the matrices were in the ranges of 1.70–3.20 and 6.10–8.50 μg/kg, respectively. The applicability of the GC–MS/MS method was demonstrated by the determination of poultry eggs obtained from local markets with no penicillin G residues.

A highly sensitive, simple, and fast gas chromatography-mass spectrometry method for the quantification of serum short-chain fatty acids and their potential features in central obesity.

Short-chain fatty acids (SCFAs) are the main gut microbe metabolites, which have no more than six carbons. SCFAs are an emerging biomarker in metabolic diseases, including central obesity. Commonly, SCFAs are measured in fecal samples, where they are highly abundant, but here they do not reflect direct interactions with related organs. Serum SCFAs are assumed to be more associated with metabolic disease than fecal SCFAs, albeit at very low concentrations. The aim of the present study is to develop a highly sensitive, simple, and fast method for measuring six SCFAs in the serum by gas chromatography-mass spectrometry (GCMS). The serum is mixed with meta-phosphoric acid and 2,2-dimethylbutyric acid, followed by homogenization and centrifugation. Supernatant is then injected into the fused silica capillary column. The method is linear from 0.12-500μmol/L for all SCFAs with an accuracy of 90-117%. The total coefficient of variation for precision ranges from 3.8 to 14.1%. A preliminary study is performed with 32 centrally obese subjects and 17 lean subjects. The mean values of all SCFAs, including acetic, propionic, isobutyric, butyric, isovaleric, and valeric acid, in the centrally obese subjects are significantly higher compared with lean subjects. A significant correlation also exists between all SCFAs, with the waist circumference indicating that serum SCFAs have potential features with respect to metabolic diseases, especially central obesity. The validated GCMS method provides highly sensitive, fast, simple, and reliable SCFA quantitation in the serum and demonstrates the potential features of circulating SCFAs in central obesity.

Simultaneous determination of compound-specific isotopic compositions of acyclic isoprenoids and n-alkanes in light crude oil.

Stable carbon and hydrogen isotope ratios of individual n-alkanes and acyclic isoprenoids are important tools in petroleum geochemistry. However, the analysis requires baseline separation and peak profiles using gas chromatography-isotope ratio mass spectrometry to obtain accurate compound-specific isotope data. Time-consuming isolation or purification is typically conducted to separate the compounds to avoid co-elution with other compounds or matrices in crude oils. We developed a simple gas chromatography separation method to simultaneously measure the compound-specific carbon or hydrogen isotope compositions of n-alkanes and acyclic isoprenoids. It was achieved by direct injection of the whole crude condensate and light oil or the saturated fractions of different types of crude oils using a 60m DB-17ms column. This method simplifies the pre-treatment of compound-specific isotope analysis, saves manpower and time, and reduces the use of organic solvents to be more environmentally friendly.

A novel procedure for stabilization of azide in biological samples and method for its determination (HS-GC-FID/FID)

Sodium azide is an old poison with toxicity comparable to potassium cyanide. It would seem to be completely forgotten however, between 2000 and 2020, the number of intentional ingestions and murders committed with sodium azide significantly increased. Furthermore, due to its extreme instability, sodium azide is difficult to detect, which poses an additional risk when used to commit a crime. In this study, the epidemiology of sodium azide exposures between 1920 and 2020 was investigated. For the determination the azide concentration in biological samples, a simple, precise and selective headspace gas chromatography method (HS-GC-FID/FID) was developed and fully validated. The limit of quantification was 0.65 µg/mL; and the limit of detection was 0.35 µg/mL; precision and accuracy did not exceed 20%. The stability study was conducted for various biological fluids (urine, bile, blood, gastric content) for 91 days in the refrigerator (4 °C) and the method for stabilization of azide was presented. The addition of a mixture of borax and sodium fluoride (w/w 3:1) to the test tubes can stabilize this poison. The described unique technique of collecting the biological samples poses a great potential for azide detection in clinical and toxicology laboratories even long time after human exposure to this substance.

Pharmacokinetic Study of Safrole and Methyl Eugenol after Oral Administration of the Essential Oil Extracts of Asarum in Rats by GC-MS.

Asarum is a traditional medicine and has been widely used as remedies for inflammatory diseases, toothache, headache, local anesthesia, and aphthous stomatitis in China, Japan, and Korea. Our previous research found that safrole and methyl eugenol were vital compounds that contribute to distinguish the different species and raw Asarum and its processed products apart. The pharmacokinetics of safrole and methyl eugenol after oral administration of Asarum extract has not been reported yet. In this study, a rapid and simple gas chromatography–mass spectroscopy (GC–MS) method that has a complete run time of only 4.5 min was developed and validated for the simultaneous determination and pharmacokinetic study of safrole and methyl eugenol in rat plasma after administration of Asarum extracts. The chromatographic separation was realized on a DB-17 column (30 m × 0.25 mm × 0.25 μm). And detection was carried out under selected ion monitoring (SIM) mode. Plasma samples were pretreated by n-hexane. The pharmacokinetic parameters provided by this study will be beneficial for further developments and clinical applications of Asarum.

Determination of organic sulfur markers in crude oils by gas chromatography triple quadrupole mass spectrometry

Organic sulfur compounds, such as benzothiophene and dibenzothiophene, are present in crude oils, and specific isomers of these classes are known to be geochemical markers of maturity, lithology and biodegradation. Thus, knowledge of the individual concentrations of these target molecules enables us to characterize petroleum basins for better exploration. In this work, a simple and effective gas chromatography–triple quadrupole mass spectrometry method without preliminary fractionation was developed and validated for the determination of 14 organic sulfur compounds assumed to be geochemical markers for crude oils. The research was focused on the optimization of a highly selective GC-based analytical strategy using triple quadrupole MS in multiple reaction monitoring. Sample preparation was carried out by simple dilution in DCM. The method was validated, and the following parameters were expressed in terms of intraday precision: linearity, limit of detection, accuracy and precision. The limit of detection ranged from 0.005 μg mL−1 (benzothiophene) to 0.159 μg mL−1 (benzonaphthothiophene). Intraday assay precision was lower than 20% in all cases. Recoveries ranged from 78.2% (1,4-dimethyldibenzothiophene) to 117% (2,4,7-trimethyldibenzothiophene). After validation, the procedure was successfully applied to the determination of S-markers in 8 crude oil samples, and the method was determined to be precise, accurate, and suitable. Diagnostic ratios based on benzothiophenes to dibenzothiphenes were applied as tools to evaluate maturity, biodegradation and depositional ambient conditions. A cross-plot of methyldibenzothiophene versus dimethyldibenzophene ratio was utilized to classify oils according to their maturity.

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.

Method development and validation for the determination of residual solvents in quinabut API by using gas chromatography. Message 2

Aim. The aim of study was to develop and validate a simple, precise and accurate method using gas chromatography for analysis of residual solvents – acetone and 2-propanol – in quinabut API. Materials and methods. All experiments were performed on a gas chromatographic system equipped with FID detector (Shimadzu GC System) using the DB-624 (30 m × 0.32 mm ID, 3.0 μm film sickness) column as stationary phase. Nitrogen was used as carrier gas with flow rate 7.5 mL/ min. Split ratio was 1:5, injector temperature was 140 °C, detector temperature was 250 °C, oven temperature was programmed from 40 °C (2 min) to 50 °C at 1 °C/min and then increased at a rate of 15 °C/min up to 215 °C; and maintained for 2 min. All solutions were prepared using water as diluent. Results. This proposed method is assessed for separation of residual solvent from quinabut with quantification. The obtained results are compared with the corresponding specified limits of ICH standard guidelines. The method validation was done by evaluating specificity, limit of detection (LOD) and limit of quantitation (LOQ), linearity, accuracy, repeatability, ruggedness, system suitability and method precision of residual solvents as indicated in the ICH harmonized tripartite guideline. The separation between acetone and 2-propanol peaks is 2.07. Hence method was found to be specific. The linear relationship evaluated across range of 15 to 180% for acetone and 2-propanol of ICH specified limit of residual solvents. The graphs of theoretical concentration versus obtained concentration are linear and the regression coefficients ‘R’ for residual solvents were more than 0.9968. The values of LOD and LOQ were much less than the lower limit of the concentration range and cannot affect the accuracy of the test. The technique was characterized by high intra-laboratory accuracy at concentrations close to the nominal acetone and 2-propanol concentration. All solutions were stable in water for at least 1 hour when stored at room temperature. Conclusion. A simple, specific, accurate, precise and rugged gas chromatography method was developed and validated for the quantification of residual solvents present in quinabut API through an understanding of the synthetic process, nature of solvents and nature of stationary phases of columns. The residual solvents acetone and 2-propanol were determined.

Optimalization of multiresidue method for the determination of pesticide residues in fruits

The main aim of this study was to optimize the QuEChERS methodology for the comprehensive determination of pesticide residues using a simple and inexpensive gas chromatography equipped with selective detectors working simultaneously (GC-ECD/NPD). The method was validated in accordance with the SANTE/11945/2015 guidelines. Representative fruit matrices were chosen from the commodities group with high water content (apples), and with high acidity and high water content (strawberry) for a 160 compounds in the range of 0.005−0.02 mg/kg. The accuracy of the method was as required (recovery: 70–120%, precision: below 20%) for 135 active substances in apples samples and 137 in strawberries samples. The main advantages of the methodology include: good detector response linearity (R2 above 0.995), low limits of detection (0.005 mg/kg for more than 20 compounds, 0.01 mg/kg for about 120 compounds), possibility of simultaneous determination of a wide range of compounds (including some “difficult” ones) without use of a single residue methods. The simultaneous use of two selective detectors allows to obtain more data during a single dose of the sample and confirmation of the result for most compounds, which allows to prevent false positives ones.