Gas Chromatographic Method For Determination Research Articles

PRESISI DAN AKURASI KROMATOGRAFI GAS DALAM PENETAPAN KADAR ASAM PROPIONAT DALAM PRODUKSI BAKERI (PRECISION AND ACCURACY OF GAS CHROMATOGRAPHY FOR DETERMINATION OF PROPIONIC ACID LEVELS IN BAKERY PRODUCT)

Percission and accurate gas chromatographic method for determination of propionic acid in bakery products was developed. Bakery productswere directly extraction with ethyl acetat and phosphoric acid used for acidic. The extract was injected directly to gas chromatographic using butyric acid as internal standard. Calibration curve propionic acid range 25 – 1000 µg/mL. Coefissien of variation (CV) rates for spiked bakery produtcs were 1,36% and 99,81% (range 96,32 – 103,61%) for accuracy at ± 1000 mg/kg propionic acid, Limit detection (LoD) and limit quantitation (LoQ) by this method were 333,6537 mg/Kg and 635,5818 mg/Kg. Burger, hot dog, and sandwich buns from a local factory at Pontianak were analyzed and respectively rates less than the limit permitted by Indonesian regulations.

A generic gas chromatography method for determination of residual solvents in PET radiopharmaceuticals

A novel gas chromatography (GC) method for quantitation of volatile organic compounds (VOCs) in 18F- and 11C-radiopharmaceuticals listed in the European Pharmacopoeia (Ph. Eur.) was proposed. Optimized chromatographic parameters were used for separation of ethanol, acetone, acetonitrile, tetrahydrofuran (THF), dibromomethane (DBM), 2-dimethylaminoethanol (deanol), N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) which could be detected in radioactive drug samples. The calculated peak resolutions (RS) were higher than 2.0 at ethanol concentration of up to 11 m/m%. Reproducible results could be obtained using base deactivated fused silica wool as packing material of inlet liner. Validation parameters showed excellent linearity (r2 ≥0.9998) in the range from 10 to at least 120% of concentration limit of solvents. The accuracy was determined as recovery of concentrations which ranged from 99.3% to 103.8%. Additionally, the relative standard deviation (RSD) of each solvent for inter-day and intra-day precision were in the range of 0.5–4.2% and 0.4–4.4%, respectively. The limit of quantitation (LOQ) for ethanol, acetone, acetonitrile, THF, DBM, deanol, DMF and DMSO was 0.48, 0.42, 0.43, 0.46, 4.35, 0.73, 0.68 and 0.50 mg/L, respectively. The developed procedure was successively applied for quantitation of ethanol, acetone, acetonitrile and deanol in radioactive drug samples of [11C]methionine, [11C]choline, 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) and O-(2-[18F]fluoroethyl)-L-tyrosine ([18F]FET). The proposed GC method applying flame ionization detection (FID) could be adapted in routine quality control of most frequently used positron emission tomography (PET) radiopharmaceuticals to perform the determination of residual solvents with analysis time of 12 min

The Method for Direct Gas Chromatographic Determination of Acetaldehyde, Methanol, and Other Volatiles Using Ethanol as a Reference Substance: Application for a Wide Range of Alcoholic Beverages

The article presents the results of collaborative study of the method for gas chromatographic determination of alcoholic fermentation volatile by-products (acetaldehyde, methanol, methyl acetate, ethyl acetate, propan-2-ol, propan-1-ol, 2-methylpropan-1-ol, butan-1-ol, and 3-methylbutan-1-ol) in alcoholic beverages with volume ethanol content in a range of 9.9–96.0% (wine, sake, liquor, tequila, vodka, grappa, bourbon, scotch, calvados, rakia, rum, brandy, whiskey, gin, and rectified ethyl alcohol). The zest of the method is the use of ethanol, present in beverages, as a reference substance for quantitative determination of mentioned components. Checking of precision data, obtained under repeatability conditions and under both repeatability and intermediate precision conditions, and trueness of test results, was carried out according to the ISO 5725–6. The relative difference between calibration coefficients (relative response factors for analyzed volatile compound relative to ethanol), obtained with an interval of 3 weeks, did not exceed 1.1%. Contents of acetaldehyde, methanol, and volatiles in 15 commercial alcoholic beverages analyzed by the developed method varied in the 1.84–677 mg L−1 of absolute ethanol, 3.25–12,394 mg L−1 of absolute ethanol, and 1.49–4243 mg L−1 of absolute ethanol intervals, correspondingly.

Development and Validation of an Automated Gas Chromatography Method for Determination of Dichloromethane in Ampicillin Sodium by Using Capillary Column Technology

Background: The main aim of the study was to develop an automated static headspace gas chromatography (SHS-GC) method for determination of dichloromethane (DCM) in ampicillin sodium by using a capillary column. Methods: SHS-GC also known as gas chromatography-headspace is the technique of choice due to its high sensitivity, excellent separation abilities, low limit of detection and simplicity of the instrumentation used for the technique. The headspace sampling method has more appropriate sensitivity than the direct injection method because it can clearly separate volatile analytes from the sample matrix and effectively concentrate them. Therefore, this method results in less complex sample preparation, decreased instrument contamination, and increased capillary column life. Results: The developed SHS-GC method showed symmetrical peak shape reasonable retention time for DCM. A linear relationship was obtained over the range of 2-240 μg mL-1 with a correlation coefficient (r2) of 0.993. The recovery, system precision and robustness of the method were within the acceptable values. The Limit of Detection (LOD) and Limit of Quantitation (LOQ) were 0.5 μg mL-1 and 2 μg mL-1 respectively. Conclusions: The results obtained in this study demonstrate that SHS-GC method is selective, precise, linear, accurate and robust for determination of dichloromethane in ampicillin sodium and its formulation (injection).

Isolation and gas chromatographic method for determination of osthole from Cnidii Fructus

The purpose of this research is to study the isolation and purification of osthole from Cnidii Fructus extract and to establish a gas chromatographic method for determining the osthole content from various Cnidii Fructus samples. Six solvents were used to extract Cnidii Fructus in order to evaluate their efficiency in extracting osthole. Vacuum fractional distillation and traditional column chromatography were compared to evaluate the efficiency in purifying osthole from Cnidii Fructus extract. Gas chromatographic method was used to determine osthole content in Cnidii Fructus extract. The analytical conditions are the following: nitrogen as the carrier gas, the flow rate of 40 mL/min; the split ratio of 120: 1. The column used was DB™-5 (30 m × 0.53 mm I.D., 1.5 μm) equipped with a flame ionization detector (FID). The initial oven temperature was programmed to be at 135°C for 12 minutes. The temperature was then raised to 215°C at a rate of 12°C /min for 20 minutes. The retention time of osthole was 24.1 min. Caffeine anhydrous was used as the internal standard with a retention time of 18.9 minutes. A comparative evaluation showed that aqueous alcoholic solvent was the most efficient solvent among six used in extraction of osthole from a Cnidii Fructus. Vacuum fractional distillation is useful for purifying osthole from Cnidii Fructus extract. It was found that the osthole content of commercial Cnidii Fructus samples varied from 0.05% to 2.14%. And the osthole content of Cnidii Fructus samples collected from Southern China was higher than those collected from Northern China.

A gas chromatographic method for determination of nicotinamide, paraben esters and caffeine in commercial health drinks, tonic drinks and cold formulas

A simple and rapid method was developed to simultaneously determine the nicotinamide, paraben as well as caffeine by using megapore immediate-polar column (CP-Sil 24CB, 30 m x 0.53 mm, 1.5 μm) with direct injection gas chromatography. Direct quantitative analysis of nicotinamide, paraben esters and caffeine in health drinks, tonic drinks, and cold formulas was carried out without any sample pretreatment procedure. The water soluble compound 1,9-nonanediol was used as an internal standard. The detection limit for nicotinamide, paraben esters and caffeine was 2 μg/mL. Recovery studies were performed using 1 mL of vitamin B drink, tonic drink and cold solution, each spiked with nicotinamide, paraben esters and caffeine at 100.0 μg, respectively. The recoveries for nicotinamide were 96, 102 and 105%, respectively, and the coefficient of variation was less than 7.2%. The recoveries for butylparaben were 105, 95, and 107%, respectively, and the coefficient of variation was less than 8.3%. The recoveries for caffeine were 101, 95 and 104%, respectively, and the coefficient of variation was less than 7.5%. Fifty-two commercial health drinks, tonic drinks and cold solutions were analyzed by the current method. The nicotinamide content was found as: 20.3-241.7, 0-210.7 and 0-246.8 μg/mL, respectively; the isobutylparaben content was found as: 0-54.1, 0-42.9 and 0-134.1 mg/mL; the butylparaben content was found as: 0-106.8, 0-120.1 and 0-184.6 μg/mL; and the caffeine content was found as: 0-433.2, 0-80.7 and 472.3-1742.9 μg/mL. These results indicated that 6 out of 18 commercial health drinks, 2 out of 12 commercial tonic drinks, and 2 out of 22 commercial cold formulas exceeded the Taiwan nicotinamide recommended daily nutrient allowances (RDNA, 14.4 μg) level. Furthermore, 25 out of 52 samples labeled 'preservative-free' were detected to be preservative-containing products. The total preservative contents in some test samples exceeded the regulation levels of 100 μg/mL; and 27 out of 30 samples were detected to be caffeine-containing products. These results were inconsistent with the CNS (Chinese National Standard) rules.

Determination of Cyclohexene in workplace air by Solvent desorption gas chromatography

Objective: To establish a solvent desorption gas chromatography method for determination of cyclohexene in workplace air. Methods: Cyclohexene in the air of workplace was collected with carbon tube and desorbed by carbon disulfide. The target toxicant was separated with the GC column and analyzed with FID detector, identified by retention time, and quantified by peak area. Results: The linear range of cyclohexene in the air of workplace was 0.77~4 050.00 μg/ml, with a correlation coefficient of 0.9999. The limit of detection was 0.23 μg/ml. The lower limit of quantification was 0.77 μg/ml. The minimum detectable concentration was 0.15 mg/m(3) under1.5 L sampling volume and 1.0 ml extraction solution volume. The within-run precision of different cyclohexene concentrations was 0.62%~1.9% and the between-run precisions was 1.5%~3.5%; The average extraction efficiency was 96.4%; Penetration capacity (100 mg of carbon tube) was 29.4 mg; The average collection efficiency was 100%; The samples could be stored for 7 days at room temperature. When placed in 4 ℃ refrigerator, the samples could be stored for 14 days. The potential coexistence of cyclohexane, hexane, benzene, toluene and ethylbenzene with cyclohexene in the air did not interfere with the results of determination. Conclusion: This method has high sensitivity, precision, accuracy and lower limit of detection and it is applicable for determination of cyclohexene in workplace air.

Static headspace gas chromatographic determination of hexanal as a marker of lipid oxidation in fat-rich food

Static headspace gas chromatographic method for determination of hexanal as a marker of lipid oxidation was developed. Tetradecane was suggested as a matrix for hexanal release from the sample. Sample equilibration temperature and time, tetradecane volume, injection time were optimized. Benzaldehyde was selected as an internal standard. Under the optimized conditions quality parameters were determined. The calibration curve was linear in the concentration range from 25 µg l–1 to 2 g l–1, the detection limit was 15 µg l–1, RSD was determined by five replication analysis with hexanal concentration 0.1 g l–1 and was 1.2%. The technique was applied for hexanal determination in potato chips and fried potatoes.

Development and validation of a thermal desorber gas chromatography method for determination of residual solvents in drug loaded albumin

The conventional approach for residual solvent (RS) analysis is headspace-gas chromatography (HS-GC). This starts from a homogenous sample solution and is based on the equilibrium of the analyte between the sample and the gas phase. Unfortunately, aqueous solutions of albumin form irreversible hydrophobic aggregates when heated above 50 °C. Consequently, the use of HS-GC for RS analysis in albumin becomes problematic due to the presence of an additional solid phase in the HS vial.In this work, a method using a thermal desorber (TD) combined with GC was developed for the determination of RS in drug loaded albumin. Samples were immobilized between two double layers of quartz filter (QF) in a polytetrafluoroethylene (PTFE) insert which was placed in an empty desorption tube prior to TD-GC analysis. The liquid standard mix consisted of ethanol (EtOH), acetone (Ace), dichloromethane (DCM) and chloroform (Chl) dissolved in toluene. Offline liquid calibration (OLC) was applied by introducing 2 μL of the standard mix under counter flow of an inert gas into the TD tube containing a mixed bed of mesoporous silica (MPSi) immobilized between two double layers of QF. The OLC results were verified using the inline liquid calibration (ILC) approach based on a heated GC injector installed on the TD. The validation results revealed that the proposed method has good recovery (> 98 %). R2-values (> 0.998) indicated good linearity over a wide range. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.01 and 0.04 μg on tube, respectively. Repeatability of the method was reported as RSD-values and they were lower than 3 %. A method based on the complete enzymatic digestion of albumin combined with conventional HS-GC was developed to verify the completeness of release of the RS from the albumin. Both the TD-GC and HS-GC methods were applied for the determination of EtOH and DCM in two different albumin samples loaded with experimental drugs. Statistical comparison indicated that there was no significant difference (p > 0.05) between the two methods. However, the HS-GC method following enzymatic degradation is much more expensive and time consuming.

A simple high-throughput headspace gas chromatographic method for the determination of dissolved oxygen in aqueous samples

This paper reports on a headspace gas chromatographic method (HS-GC) for the accurate determination of dissolved oxygen (DO) in domestic and industrial wastewater. It was based on GC measurement of oxygen in the headspace gas that is released from the dissolved oxygen in a liquid sample in a closed vial. The results show that the relative standard deviation of the method in quintuplicate testing was < 2.0% and the relative differences of results were less than 4.0% for the real river water samples when compared with the widely used reference method (the electrode method); The linear range of the method is about 0–9.0 mg/L with the limit of detection of 0.30 mg/L. The present method is simple in both sample preparation and method calibration. It is particularly efficient in the batch testing mode. Overall, the method is more reliable than the current reference method when used with samples from a wide range of sources.

Determination of Sevoflurane, Isoflurane and Enflurane in the air of workplace by gas chromatography

Objective: To establish a solvent desorption gas chromatographic method for determination of Sevoflurane, Isoflurane and Enflurane in the air of the Workplace. Methods: Sevoflurane, Isoflurane and Enflurane were collected with activated carbon tube and desorbed with dichloromethane, separated with DB-1 capillary columns, and then detected with flame ionization detector. Results: The linearity ranges were 1.9-304.8 μg/ml for Sevoflurane, 2.1-300.4 μg/ml for Isoflurane and 1.7-305.2 μg/ml for Enflurane, The correlation coefficient was both >0.999. Their limits of detection were 0.6 μg/ml, 0.6 μg/ml and 0.5 μg/ml, and Their limits of quatification were 1.9 μg/ml, 2.1 μg/ml and 1.7 μg/ml, and their minimum detectable concentrations were 0.1、0.2 and 0.1 mg/m(3) per 4.5 L of air. Their relative standard deviations (RSD) were 2.5%-3.0%, 2.3%-3.1% and 2.2%-3.0%. The average desorption efficiencies were 101.1%-103.3%, 100.7%-102.7% and 101.0%-102.9%. The sampling efficiency was both 100%. The breakthrough volume of 100 mg actived carbon was 3.7 mg, 3.4 mg and 3.4 mg. Sevoflurane, Isoflurane and Enflurane in activated carbon tube could be kept at least 10 days at room temperature without significant losses. Conclusion: The method shows lower detection limit, high accuracy and precision. It is feasible for determination of Sevoflurane, Isoflurane and Enflurane in the air of workplace.

Determination of Five Phthalate Esters and Bisphenol A in Fruit Juice by Packed-nanofiber Solid Phase Extraction Coupled with Gas Chromatography

Packed-nanofiber solid phase extraction (PFSPE) combined with gas chromatography-flame ionization detector (GC-FID) was developed for the simultaneous determination of five phthalate esters (PAEs) and bisphenol A (BPA) in fruit juice. The PAEs and BPA was concentrated by PFSPE using polystyrene- pyridine (PS-PD) nanofibers as the sorbent, followed determined by GC-FID. Under this modified procedure, satisfied recoveries in fruit juice sample ranging from 81.9% to 109.6% were obtained. And relative standard deviation values (RSD) were ranged from 1.9 % to 9.8% in orange juice sample. The limits of detection (LOD) and the limits of quantification (LOQ) of five PAEs and BPA were ranged from 0.02 μg/mL to 0.30 μg/mL and 0.06 μg/L to 1.10 μg/L, respectively. This established method was successfully applied to detect real fruit juice samples, which were collected in local supermarket. These results demonstrated the applicability of the established PFSPE-based extraction coupled with gas chromatography method for determination of PAEs and BPA in fruit juice products.

Extensive Validation of Gas Chromatographic Method for Determination of Esters in Wines Using Monolithic Materials as Preconcentration Step

A comprehensive validation of a quantitative method is a critical issue for food analysis, which requires reliable estimation of uncertainties influencing measurements. Esters as important contributors to fruity aroma generally affect quality of wine and its organoleptic features. In this study, a full validation of the method developed for quantification of esters with uncommon silica monolithic discs and gas chromatographic analysis is presented. Two types of sorbent modification and a few desorption solvents were tested for ester removal from wine samples. Uncertainty contributions from mass balance tolerance, purity of chemicals, volume measurements, calibration curve deviation and extraction procedure were included in the calculation of the combined uncertainty. The expanded uncertainty of ester determination ranged from 15 to 37% and was mainly affected by uncertainty of calibration curve. The proposed method provided a limit of detection and a limit of quantification of 0.005–0.168 μg/L and 0.018–0.560 μg/L, respectively. Additional measurements revealed a recovery range of 70–111%, average reproducibility of instrument response less than 4%, and repeatability of the method below 16% for most of esters.

A Gas Chromatographic Method for the Determination of Bicarbonate and Dissolved Gases

A gas chromatographic method for the rapid determination of aqueous carbon dioxide and its speciation into solvated carbon dioxide and bicarbonate is presented. One-half mL samples are injected through a rubber septum into 20-mL vials that are filled with 9.5 mL of 0.1 N HCl. A one mL portion of the headspace is withdrawn and injected onto a gas chromatograph equipped with a thermal conductivity detector. Using the dimensionless Henry’s constant for carbon dioxide and an adaptation of the Henderson-Hasselbalch equation, carbon dioxide in the samples can be categorized among solvated, bicarbonate, and carbonate forms. Natural water samples as well as wastewater from a municipal sewage treatment plant and a swine rearing operation were analyzed by this method and the results compared favorably to those obtained by titration. Samples stored for up to five weeks showed no significant changes in carbon dioxide concentrations. In addition, using flame ionization and electron capture detectors, methane and nitrous oxide concentrations in the samples were also measured.

Determination of tert-butyl alcohol in the air of the workplace by solvent desorption gas chromatography

Objective: To establish solvent desorption gas chromatographic method for determination of tert-butyl alcohol in the air of the workplace. Methods: After tert-butyl alcohol in the air of the workplace collected with activated carbon tube and desorbed with 2% 2-propanol in CS2, and then separated with DB-FFAP capillary column and detected with flame ionization detector. Results: The linearity ranges were 0.6~2 264.0 mg/L. The limit of quantification was 0.6 mg/L. The determination has a good reproducibility. The intraassay and interassay precisions were 2.8%~3.2% and 3.8%~5.7%. The desorption efficiencies were 93.9%~98.1%. Absorption efficiencies were 95.8%~100.0%. The breakthrough volume was above 7.1 mg in 100mg activated carbon. The samples in activated carbon tube could be stored for at least 14 days at ambient temperature. Conclusion: The method is feasible for determination of tert-butyl alcohol in the air of the workplace.

An improved back-flush-to-vent gas chromatographic method for determination of trace permanent gases and carbon dioxide in ultra-high purity ammonia

A novel method for rapid, quantitative determination of trace permanent gases and carbon dioxide in ultra-high purity ammonia by dual-channel two-dimensional GC-PDHID is presented. An improved matrix back-flush-to-vent approach combining back-flush column switching technique with auxiliary NaHSO4 ammonia trap is described. The NaHSO4 trap prevents traces of ammonia from entering the analytical column and is shown not to affect the impurity content of the sample. The approach allows shortening the analysis time and increasing the amount of measurements without extensive maintenance of the GC-system. The performance of the configuration has been evaluated utilizing ammonia- and helium-based calibration standards. The method has been applied for the analysis of 99.9999+% ammonia purified by high-pressure distillation at the production site.

A quantitative gas chromatographic method for determination of soybean seed fatty acid components

To develop an absolute quantitative method for fatty acid determination,a quantitative method for fatty acid determination was established through heated- methylation extraction method and gas chromatography( GC) analysis. Five individual fatty acid methyl esters( i. e. methyl palmitate,methyl stearate,methyl oleate,methyl linoleate and methyl linolenate) were used as the standard samples. According to the standard curves( R20. 99) and the regression equations of five kinds of fatty acid methyl esters,the absolute concentration of fatty acid of soybean seeds could be determined accurately. Through determination of fatty acids in four soybean varieties with different oil content and comparison of the total fatty acid contents with the total fat contents of them,we suggested the extraction efficiency and detection reproducibility of fatty acid could be significantly improved. In addition,the total concentration of five fatty acid detected by this method accounted for more than 94% of total fat content in soybean seeds. It concluded that this method could be used to detect not only the relative percentage content but also the absolute concentration of individual fatty acids in soybean seeds,which could play an important role in soybean fatty acid determination and breeding.

Determination of n-pentanol in workplace air by solvent desorption gas chromatography

To develop a solvent desorption gas chromatographic method for determination of n-pentanol in the workplace air. n-Pentanol in the workplace air was collected with activated carbon tubes, desorbed with 2% 2-propanol in carbon disulfide, separated with a nitroterephthalic acid-modified FFAP capillary column, and detected with flame ionization detector. The limit of detection was 0.2 mg/L; the lower limit of quantification was 0.6 mg/L; the linear range was 0.6-4072.0 mg/L. The minimum detectable mass concentration was 0.2 mg/m3 for 1.5 L of air sample. This method was highly repeatable. The relative standard deviations were 2.3%-5.4%. The average desorption efficiencies were 86.9%-94.2%. The absorption efficiencies were 100%. The breakthrough volume was above 8.0 mg in 100-mg activated carbon. The samples in activated carbon tubes could be stored for at least 14 days at room temperature. The method is feasible for determination of n-pentanol in the workplace air.

Determination of methyl propyl ketone in air of workplace by capillary gas chromatography

To establish a gas chromatography method for determination of methyl propyl ketone in the air of workplace. Methyl propyl ketone in the air of workplace was collected with activated carbon tubes and desorbed with carbon disulfide before sample loading. The target toxicant was separated with the capillary column and detected with a hydrogen flame ionization detector, identified by retention time, and quantified by peak area. The linear range of methyl propyl ketone in the air of workplace was 202.5∼4 860.0 µg/ml, with a correlation coefficient of 0.999 98. The limit of detection was 1.5 µg/ml. The lower limit of quantification was 5.0 µg/ml. The minimum detectable concentration was 1.0 mg/m(3) under 1.5 L sampling volume and 1.0 ml desorption solution volume. The relative standard deviation of different methyl propyl ketone concentrations was 1.42%∼1.65%, and the recovery rate was 94.9%∼ 97.9%. This method has high sensitivity, precision, and accuracy, and it is applicable for determination of methyl propyl ketone in the air of workplace.

A Simple and Sensitive Gas Chromatography Method for Determination of Isosorbide Dinitrate and its Metabolites in Human Plasma: Application to Pharmacokinetics Study on Oral Spray

A sensitive method for the simultaneous determination of isosorbide dinitrate (ISDN) and its mononitrate metabolites, isosorbide 2-mononitrate and isosorbide 5-mononitrate (IS-2-MN and IS-5-MN), in human plasma was developed using capillary gas chromatography with electron-capture detection, whereas 1,2,4-butanetriol trinitrate was used as internal standard. The analytes were extracted with a simple liquid-liquid extraction from plasma and separated on a DB-1 column. The results of method validation demonstrated that the calibration curves were linear in range of 2-60 ng/mL for ISDN and IS-5-MN, 1-20 ng/mL for IS-2-MN, respectively. The precision (RSD%) was less than 15%, and the lower limit of quantitation was identifiable and reproducible at 2 ng/mL for ISDN and IS-5-MN, 1 ng/mL for IS-2-MN. The analytes in plasma were stable after being stored for more than 30 days and after 2 freeze-thaw cycles (-20 to 25°C). And then this method was successfully applied to a pharmacokinetic investigation on isosorbide dinitrate oral spray in healthy volunteers.