A Single-Column Gas Chromatography Method for Quantifying Toxic Alcohols.

Background The reference method to analyze ethylene glycol (EG) is Gas Chromatography (GC). However, GC instruments are not available in most clinical laboratories, causing EG testing to be sent out. This prolongs turnaround time and delays treatment, which is precarious given the short (30min-12hr) onset for life-threatening CNS and metabolic effects from EG intoxication. To address the need for acute determination of EG levels, we evaluated the analytical performance of Catachem’s EG open channel assay on a Beckman AU5800 chemistry analyzer in the core laboratory of Grady Memorial Hospital, a large safety-net provider of emergency care in Atlanta. Methods Assay linearity and analytical measurement range (AMR) were verified in triplicate using Catachem’s linearity material. Within-run and day-to-day precision (twice over 10 days) were tested using two Catachem controls. Analytical sensitivity was assessed by running blank and spiked patient samples with low EG concentrations in quadruplicate over 4 days. Limit of detection (LOD) was calculated as limit of blank + 1.65×standard deviation of low EG spiked samples. Limit of quantification (LOQ) was determined by the lowest EG concentration at which maximum allowable precision was 20%. Method comparison was performed using residual patient serum samples collected in serum separator tubes (n=35) and spiked with EG (Sigma-Aldrich, 5M solution) at concentrations spanning the AMR. An independent hospital lab offering the same Catachem EG assay configured on a Roche Cobas C502 served as the comparative method. A reference interval was determined from 30 patient serum samples with normal osmolality (272-297 mOsm/kg). Sample carryover was determined using patient samples spiked with high or low EG concentration according to the protocol described by EP Evaluator. To assess analytical specificity, 3 neat and 3 EG spiked patient samples were run in duplicate using methanol (99%, Cardinal Health), ethanol (95%, Pharmco), isopropanol (70%, Hydrox), and acetone (99%, Fisher) at final concentrations of 2000 mg/dL. No spike-ins changed sample volume by more than 5%. Results The assay was linear between 0-300.0 mg/dL (y-intercept of -2.8 mg/dL, slope=0.95). Precision studies using 2 levels of QC demonstrated a within run CV=1.6% for each level and day-to-day run CV=3.9% (mean=53.9 mg/dL) and 2.8% (mean=247.3 mg/dL). Total Allowable Error (TAE) for within-run and day-to-day precision were 5.0% and 6.7%, respectively. Limit of detection (LOD) and limit of quantification (LOQ) were 2.0 mg/dL and 4.0 mg/dL, respectively. Method comparison exhibits an allowable slope of 0.96, y-intercept of 2.0, correlation coefficient (r) of 0.99, and average bias of -1.4 mg/dL. Carry over error of -0.4mg/dL was below the error limit of 1.0mg/dL and not clinically significant. All 30 patient samples with normal osmolality resulted with EG concentrations

The degradation mode of sorbic acid, dehydroacetic acid, methyl- and propyl-p-hydroxybenzoate in aqueous solution respectively was studied, using gas chromatographic assay method. It was noted that sorbic acid both in acidic and alkaline region was the most stable of these preservatives, whereas dehydroacetic acid was rapidly decomposed either in acidic or in strong alkaline and, hydrolysis of p-hydroxybenzoate was observed in alkaline region.The simultaneous detection of 2, 6-dimethyl-4-pyrone, 2, 6-dimethyl-4-pyrone-3-carboxylic acid, triacetic acid lactone and 2, 6-dihydroxy-2, 5-heptadien-4-one (diacetylacetone) as presumable degradation products of dehydroacetic acid could be readily implemented with direct injection gas chromatography.The degradation mechanisms of dehydroacetic acid and 2, 6-dimethyl-4-pyrone-3-carboxylic acid, both in acidic solution at 60° respectively, were followed by gas chromatography at a given time interval. As degradation products of dehydroacetic acid and 2, 6-dimethyl-4-pyrone-3-carboxylic acid, 2, 6-dihydroxy-2, 5-heptadien-4-one (diacetylacetone) and 2, 6-dimethyl-4-pyrone were identified with direct injection gas chromatography, and 3-carboxy-2, 6-dihydroxy-2, 5-heptadien-4-one was separable newly as the ester.According to the degradation products, the degradation pathway of dehydroacetic acid in acidic solution was considered to be the fact that of the lactone ring dehydroacetic acid was first broken to produce 3-carboxy-2, 6-dihydroxy-2, 5-heptadien-4-one, and then its decarboxylation immediately following the reaction yielded 2, 6-dihydroxy-2, 5-heptadien-4-one, which was dehydrated finally to 2, 6-dimethyl-4-pyrone.

In this paper, a new headspace gas chromatography (HSGC) method has been developed for the determination of ethylene oxide (EO) and 1,4-Dioxane (Dioxane) in bulk lots of polyethylene glycols (PEG). PEG samples are dissolved in dimethyl sulfoxide, heated in a headspace oven maintained at 90°C for 10min and then injected into the GC system for analysis. Analytes are separated through a thermal gradient elution from 36 to 240°C on an Agilent DB-624 column (60m × 0.53mm diameter, film thickness 3.00μm). The carrier gas is helium and detector is flame ionization detector. Total run time of the new HSGC method is about 18min. In the new HSGC method, other common residual solvents present in PEGs such as methanol (MeOH), methyl formate (MF) and acetyl aldehyde (Acetal) are also sufficiently separated from EO and Dioxane peaks. In the HSGC methods prescribed in USP monograph <228> and EP monograph <2.4.25>, EO co-elutes with MF. The new HSGC method was successfully validated according to current ICH/VICH guidelines and was found to be specific, linear, accurate, precise, robust and sensitive. This HSGC method is fast and quality control (QC) friendly and suitable for routine analysis for the determination of EO and Dioxane in bulk batches of PEGs in QC laboratories.

Gas chromatographic determination of malonaldehyde formed by lipid peroxidation

Automation of gas chromatography instruments. Part II. A knowledge-based system for performance assessment

Comparison of gas and liquid chromatography for analysing polar pesticides in water samples

Liquid chromatography of active principles in Sophora flavescens root

Screening Brazilian Automotive Gasoline Quality through Quantification of Saturated Hydrocarbons and Anhydrous Ethanol by Gas Chromatography and Exploratory Data Analysis

Toxic alcohol exposures are an ongoing concern in the United States. In the US, few studies characterize the local epidemiology of toxic alcohols over time. The objective was to examine the incidence of toxic alcohol ingestions and changes in management over time. This retrospective cohort study evaluates toxic alcohol ingestion phone calls to a regional poison center in the United States covering four states. Data were queried for this poison center from the National Poison Data System (NPDS) using generic codes for each toxic alcohol. Inclusion criteria were ingestion of toxic alcohol, age ≥ 13years, from January 1, 2000 to Dec 31, 2017. Exclusion criteria were unrelated effects coded in the medical outcome, duplicate data, or incomplete demographic data. Of 926 subjects (adults and teenagers), 71.5% were male, and the mean age was 34.5years. Toxic alcohol ingestion was more common in individuals younger than 40years, with a significant relationship between age and intentional abuse or misuse (p = 0.001). There was also a significant relationship between age and reason for ingestion, with younger patients more likely to be suicidal (p < 0.001). Ethyleneglycol was the most common toxic alcohol. There was no change in the incidence of toxic alcohol ingestions over the study period. The mortality rate was 1.7%, and 31.2%of patients were hospitalized in a critical care unit. Major effects and death were more common in younger patients (p < 0.001). There was a significant difference in medical outcomes based on the type of toxic alcohol(p = 0.03). Fomepizole was the most common treatment. A Poisson regression model found no change in fomepizole use during the study period (p = 0.1). Ethanol administration over the study period increased (p = 0.02), while hemodialysis decreased (p = 0.02). Data obtained from a single regional United States poison center showed low mortality related to toxic alcohol ingestions. The most prevalent toxic alcohol was Ethylene glycol. In all cases, toxic alcohol ingestion was higher in the 20-29-year-old age group. Reasons for ingestion, in most cases, were suicidal. Fomepizole was the most common treatment, ethanol administration as an antidote is rising, and hemodialysis utilization is decreasing. Data may not be nationally representative.

In this study, a rapid and simple method without a derivatization process for determination of the free sterols in vegetable and animal oils was developed. A direct injection gas chromatography with a non-polar megabore column (DB-1, 5 m × 0.53 mm, 1μm) was used. The recoveries of cholesterol, campesterol, stigmasterol and β-sitosterol from lard were at the range of 89%-106% with a coefficient of variation less than 12%. Total sterols were determined using the same method after saponification of the oil sample. Fourteen samples, including olive oil, sunflower oil, peanut oil, soybean oil, sesame oil, lard and egg yolk oil, were quantitatively analyzed for total and free sterols. The contents of total cholesterol, brassicasterol, campesterol, stigmasterol, β-sitosterol, Δ5-avenasterol, Δ7-stigmastenol and Δ7-avenasterol in test samples were at the range of 193-34384, 0-1222, 0-2356, 0-1365, 0-5414, 0-608, 0-1296 and 0-129 μg/g, respectively; while the contents of free cholesterol, brassicasterol, campesterol, stigmasterol, β-sitosterol, Δ5-avenasterol, Δ7-stigmastenol and Δ7-avenasterol were 98-30340, 0-1057, 0-634, 0-724, 0-3087, 0-404, 0-558 and 0-23 μg/g, respectively. The amounts of esterified sterols were calculated by subtracting the free sterol contents from total sterol contents. Results showed olive oil, sunflower oil and peanut oil primarily contain esterified sterols; while soybean oil, sesame oil, lard and egg oil contain mostly free sterols. The developed method is recommended as a rapid method to determine if animal fats/oils are adulterated with vegetable oils.

Existing methods for the measurement of plasma or tissue alphaxalone concentrations by gas chromatography are not wholly satisfactory because of the problems of interfering peaks and detector contamination by the silylation reagent. This paper describes an alternative gas chromatographic method using the nitrogen selective alkali flame ionization detector. Plasma samples from patients given Althesin (alphaxalone-alphadolone acetate) were extracted with light petroleum. O-Methyl oximes were formed using methoxyamine hydrochloride, and the O-methyloxime-3-acetate prepared by heating the extract with acetic anhydride-pyridine. Gas liquid chromatography was carried out on a column of 3% OV 17 ON Celite 545 (mesh 80-100), initial temperature 235 degrees C and increasing by a degree C min-1. Comparison has been made of the O-methyl oxime acetates with trimethylsilyl ethers using both gas chromatography and gas chromatography-mass spectrometry. The results of the two methods were not significantly different. The coefficient of variation for the O-methyloxime-3-acetates at a plasma concentration of 1.09 microliter-1 was 6.9%. This method has an improved sensitivity and selectivity over the existing method, and allows determination of the plasma alphaxalone concentrations found in patients receiving Althesin-supplemented anaesthesia.

Under normal conditions, 1,2-dimethoxyethane (DME) is a colorless and transparent liquid with a faint odor of ether, very soluble in water, charac-terized by a high vapor pressure. It belongs to the group of alkyl ethers solvents, derivatives of eth-ylene glycol. 1,2-Dimethoxyethane is used as an ex-cipient in preparing and processing industrial chemicals, in the production of fluoric polymers and as a solvent and cleaning agent in the microe-lectronics and printing industries. In the literature there are no data on the acute and chronic toxicity of 1,2-dimethoxyethane. However, long-term epidemiological studies on compounds of similar chemical structure suggest that human exposure to ethylene glycol alkyl ethers can ad-versely affect fertility and fetal development, and hematological parameters. The aim of this study was to develop and validate a sensitive method for determining concentrations of 1,2-dimethoxyethane in workplace air in the range from 1/20 to 2 MAC values, in accordance with the requirements of Standard No. PN-EN 482+A1: 2016-1. The study was performed using a gas chromato-graph (GC). A 7890B Agilent Technologies gas chromatograph with a 5977A mass spectrometry detector (MSD), HP PONA (50 m; 0,2 mm; 0,5 μm) capillary analytical column, auto sampler and Mass Hunter software was used for chromato-graphic separations. The method is based on the adsorption of 1,2-di-methoxyethane on charcoal, desorption with di-chloromethane and GC/MSD analysis of the re-sulting solution. Extraction efficiency of 1,2-di-methoxyethane from charcoal was 96.4%. Samples of 1,2-dimethoxyethane can be stored in refrigera-tor for up to 28 days. The use of a HP-PONA capil-lary column enabled selective determination of 1,2-dimethoxyethane in a mixture of dichloromethane, toluene, carbon disulfide, ethylene and propylene glycol and other compounds. The method is linear (r = 0.9999) within the inves-tigated working range from 5 to 200 μg/ml, which is equivalent to air concentrations from 0.5 to 20 mg/m3 for a 10-L air sample. The limit of quan-tification (LOQ) is 1,306 μg/ml. The analytical method described in this paper ena-bles selective determination of 1,2-dimethoxye-thane in workplace atmosphere in presence of other compounds at concentrations from 0.5 to 20 mg/m3 (1/20 ÷ 2 MAC value). The method is precise, accurate and it meets the criteria for proce-dures for measuring chemical agents listed in Standard No. PN-EN 482+A1: 2016-1. The method can be used for assessing occupational exposure to 1,2-dimethoxyethane and associated risk to work-ers’ health. The developed method of determining 1,2-di-methoxyethane has been recorded as an analytical procedure (see Appendix).

Oxidative stress induces functional changes in arteries. Therefore, the effect of myo-inositol, a possible anti-inflammatory/antioxidant agent was studied on human plasma and rat thoracic arteries. Aortic rings from male Wistar rats (3 months of age) were incubated with myo-inositol (1, 10 and 100 μM, 120 min) and analyzed using the gas chromatography (GC) method. In another experiment, aortic rings were protected first with myo-inositol (1 µM, 60 min) and then subjected to a thromboxane receptor agonist (U-46619, 0.1 nM, 60 min). Therefore, these four groups under the following conditions were studied: (i) the control in the vehicle; (ii) myo-inositol; (iii) the vehicle plus U-46619; (iv) myo-inositol plus U-46619. The hemostatic parameters of human plasma and an H2O2/Fe2+ challenge for lipid and protein peroxidation were also performed. Myo-inositol was not absorbed into the pre-incubated aortic rings as measured by the GC method (0.040 µg/mg, p ≥ 0.8688). The effect of myo-inositol was more significant in the impaired arteries due to U-46619 incubation, which resulted in an improved response to acetylcholine (% Emax: 58.47 vs. 86.69), sodium nitroprusside (logEC50: −7.478 vs. −8.076), CORM-2 (% Emax: 44.08 vs. 83.29), pinacidil (logEC50: −6.489 vs. −6.988) and noradrenaline (logEC50: −7.264 vs. −6.525). This was most likely a possible response to increased nitric oxide release (×2.6-fold, p < 0001), and decreased hydrogen peroxide production (×0.7-fold, p = 0.0012). KCl-induced membrane depolarization was not modified (p ≥ 0.4768). Both the plasma protein carbonylation (×0.7-fold, p = 0.0006), and the level of thiol groups (×3.2-fold, p = 0.0462) were also improved, which was not significant for TBARS (×0.8-fold, p = 0.0872). The hemostatic parameters were also not modified (p ≥ 0.8171). A protective effect of myo-inositol was demonstrated against prooxidant damage to human plasma and rat thoracic arteries, suggesting a strong role of this nutraceutical agent on vasculature which may be of benefit against harmful environmental effects.

The causes of the difference in fatty acid composition between gas chromatography (GC) and near-infrared fiber-optic method (NIR) in bovine fat and their countermeasures were studied using absolute values of refractive index. Using intermuscular fat from 45 crossbreeds, refractive index was measured by using a refractometer, and saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) were measured by NIR and GC. The correlation coefficients between GC and NIR in SFA and MUFA, as well as those between refractive index and GC or NIR (in SFA and MUFA), were all greater than or equal to 0.8 (p < 0.01). In samples with 3% or more difference between GC and NIR in SFA and MUFA, GC and NIR values were often located in opposite directions to the regression lines with regard to refractive index. GC reanalysis on these samples slightly increased the correlation coefficient between GC and refractive index and reduced the difference between GC and NIR by 1%-2%. Results indicate that measurement errors in GC and NIR are related to their more than 3% difference, and GC reanalysis based on refractive index may improve its accuracy.

The characterization of industrial yeast strains by examining their metabolic footprints (exometabolomes) was investigated and compared to genome-based discriminatory methods. A group of nine industrial brewing yeasts was studied by comparing their metabolic footprints, genetic fingerprints and comparative genomic hybridization profiles. Metabolic footprinting was carried out by both direct injection mass spectrometry (DIMS) and gas chromatography time-of-flight mass spectrometry (GC-TOF-MS), with data analysed by principal components analysis (PCA) and canonical variates analysis (CVA). The genomic profiles of the nine yeasts were compared by PCR-restriction fragment length polymorphism (PCR-RFLP) analysis, genetic fingerprinting using amplified fragment length polymorphism (AFLP) analysis and microarray comparative genome hybridizations (CGH). Metabolomic and genomic analysis comparison of the nine brewing yeasts identified metabolomics as a powerful tool in separating genotypically and phenotypically similar strains. For some strains discrimination not achieved genomically was observed metabolomically.