Gas-liquid Chromatographic Measurements Research Articles

Abraham Solvation Parameter Model: Calculation of L Solute Descriptors for Large C11 to C42 Methylated Alkanes from Measured Gas–Liquid Chromatographic Retention Data

Abraham model L solute descriptors have been determined for 149 additional C11 to C42 monomethylated and polymethylated alkanes based on published Kovat’s retention indices based upon gas–liquid chromatographic measurements. The calculated solute descriptors, in combination with previously published Abraham model correlations, can be used to predict a number of very important chemical and thermodynamic properties including partition coefficients, molar solubility ratios, gas–liquid chromatographic and HPLC retention data, infinite dilution activity coefficients, molar enthalpies of solvation, standard molar vaporization and sublimation at 298 K, vapor pressures, and limiting diffusion coefficients. The predictive computations are illustrated by estimating both the standard molar enthalpies of sublimation and the enthalpies of solvation in benzene for the monomethylated and polymethylated alkanes considered in the current study.

Abraham model correlations for describing the partition of organic compounds from water into the methyl ethyl ketone extraction solvent

ABSTRACT Experimental water-to-methyl ethyl ketone partition coefficients have been determined for 34 different organic solutes at ambient room temperature based on gas–liquid chromatographic measurements. Updated Abraham model correlations were determined for describing solute transfer into methyl ethyl ketone by combining the measured partition coefficient data determined in the present study with published experimental values taken from chemical and engineering literature. Experimental data for 48 compounds were used in determining the revised Abraham model correlations. The revised mathematical correlations were determined to back-calculate the observed partition coefficient data to within an overall average standard deviation of 0.17 log units or less. The partitioning characteristics of the water-to-methyl ethyl ketone system are compared to the characteristics of two other biphasic water-to-ketone partitioning systems.

Determinations of gas–liquid partition coefficients using capillary chromatographic columns. Alkanols in squalane

This study focused on an investigation into the experimental quantities inherent in the determination of partition coefficients from gas–liquid chromatographic measurements through the use of capillary columns. We prepared several squalane – (2,6,10,15,19,23-hexamethyltetracosane) – containing columns with very precisely known phase ratios and determined solute retention and hold-up times at 30, 40, 50 and 60°C. We calculated infinite dilution partition coefficients from the slopes of the linear regression of retention factors as a function of the reciprocal of the phase ratio by means of fundamental chromatographic equations. In order to minimize gas–solid and liquid–solid interface contributions to retention, the surface of the capillary inner wall was pretreated to guarantee a uniform coat of stationary phase. The validity of the proposed approach was first tested by estimating the partition coefficients of n-alkanes between n-pentane and n-nonane, for which compounds data from the literature were available. Then partition coefficients of sixteen aliphatic alcohols in squalane were determined at those four temperatures. We deliberately chose these highly challenging systems: alcohols in the reference paraffinic stationary phase. These solutes exhibited adsorption in the gas–liquid interface that contributed to retention. The corresponding adsorption constant values were estimated. We fully discuss here the uncertainties associated with each experimental measurement and how these fundamental determinations can be performed precisely by circumventing the main drawbacks.The proposed strategy is reliable and much simpler than the classical chromatographic method employing packed columns.

ChemInform Abstract: Hydrogen Bonding. Part 18. Gas-Liquid Chromatographic Measurements for the Design and Selection of Some Hydrogen Bond Acidic Phases Suitable for Use as Coatings on Piezoelectric Sorption Detectors.

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PlANT-ASSOCIATED BACTERIA AS TOOLS FOR THE PHYTOREMEDIATION OF OILY NITROGEN-POOR SOILS

The rhizospheres and phyllospheres of peas, beans, tomatoes, and squash raised in a desert sand soil mixed with 0.5% crude oil were rich in oil-utilizing bacteria and accommodated large numbers of free-living diazotrophic bacteria, with potential for hydrocarbon utilization. According to their 16S rRNA-sequences, the cultivable oil-utilizing bacteria were affiliated with the following genera, arranged in decreasing frequency: Bacillus, Ochrobactrum, Enterobacter, Rhodococcus, Arthrobacter, Pontola, Nocardia, and Pseudoxanthomonas. Diazotrophic isolates were affiliated with Rhizobium, Bacillus, Rhodococcus, Leifsonia, Cellulosimicrobium, Stenotrophomonas, Kocuria, Arthrobacter, and Brevibacillus. The crude oil–utilizing and diazotrophic isolates grew, with varying growth intensities, on individual aliphatic (C8 to C40) and aromatic hydrocarbons, as sole sources of carbon and energy. Quantitative gas liquid chromatographic measurements showed that representative bacterial isolates eliminated pure n-hexadecane, n-decosane, phenanthrene, and crude oil from the surrounding liquid media. Cultivation of oily sand–soil samples with any of the four tested crops led to enhanced oil degradation in that soil, as compared with the degradation in uncultivated oily sand–soil samples.

Temperature Dependence of Infinite Dilution Activity Coefficients in Octanol and Octanol/Water Partition Coefficients of Some Volatile Halogenated Organic Compounds

Infinite dilution activity coefficients and Henry's law coefficients have been measured for 11 halogenated C 1 to C 3 compounds in 1-octanol above room temperature using a gas-liquid chromatographic measurement method. Then, using our earlier data for these substances in water and a correlation relating the limiting activity coefficients of a substance in pure water and in pure 1-octanol to their octanol/water partition coefficients, these latter quantities have been computed. One conclusion from these measurements is that the limiting activity coefficients in octanol and the octanol/water partition coefficients of the halogenated compounds studied are only weakly dependent on temperature over the range from 25 to 50°C. Also, from these and our earlier data, we have estimated the infinite dilution partial molar excess enthalpies and excess entropies of these compounds in both 1-octanol and water.

Determination of second cross virial coefficients from gas-liquid chromatographic data: II. Dilute mixtures of water and brominated hydrocarbons

Gas-liquid Chromatographic measurements were carried out in the temperature range 298–323 K and were used to determine the second cross virial coefficients for each brominated hydrocarbon-carrier gas mixture studied. Measurements on mixtures of brominated compounds infinitely dilute in water were made using a gas-liquid Chromatographic apparatus with a packed column under carrier gas inlet pressures up to 700 kPa and with water as the stationary phase. Nitrogen was used as the carrier gas. In addition, mixtures of water infinitely dilute in the brominated compounds were studied using an isopiestic apparatus. Henry's constants were also derived and group interaction parameters for the UNIFAC correlation were estimated using the experimental infinite dilution activity coefficients. The new group interaction parameters were used to predict activity coefficients for a range of brominated hydrocarbon-water mixtures.

Determination of infinite dilution activity coefficients and second virial coefficients using gas-liquid chromatography I. the dilute mixtures of water and unsaturated chlorinated hydrocarbons and of water and benzene

Specific-retention volume data from gas-liquid chromatographic measurements can be used to obtain infinite dilution activity coefficients second cross virial coefficients for the solute-carrier gas mixtures. The gas-liquid chromatographic measurements have been carried out for benzene three unsaturated chlorinated hydrocarbon + water mixtures in the temperature range 285.15–323.15 K, with water as stationary phase and nitrogen as carrier gas. A gas-liquid chromatographic apparatus was used for measurements on water rich mixtures, and organic rich mixtures were studied using an isopiestic technique. The chromatographic specific retention volume data and the results from the isopiestic technique may be used to estimate group interaction parameters for the UNIFAC correlation to predict activity coefficients.

Determination of Infinite Dilution Activity Coefficients and 1-Octanol/Water Partition Coefficients of Volatile Organic Pollutants

The characterization of pollutants is of growing interest as concerns about the environment increase. One parameter useful in predicting the fate of a chemical in the environment, the infinite dilution activity coefficient, has been determined here for several EPA priority pollutants in 1-octanol at 25 C using a relative gas-liquid chromatographic measurement technique. A simple correlation has been developed relating the limiting activity coefficients of a species in pure water and in pure 1-octanol to its octanol/water partition coefficient. Agreement between the experimental results and published values is very good. The method developed here of computing the octanol/water partition coefficient from gas chromatographic measurements of its infinite dilution activity coefficients is an improvement over traditional partition coefficient determination methods in that it is easier and quicker, without a loss of accuracy. Furthermore, the authors show that this method is applicable to chemicals covering a large range of hydrophobicities (1.0 < log K[sub OW] < 5.0).

Hydrogen bonding. Part 18. Gas–liquid chromatographic measurements for the design and selection of some hydrogen bond acidic phases suitable for use as coatings on piezoelectric sorption detectors

A number of involatile liquids based on 4,4′-isopropylidenediphenol (bisphenol-A) or other bisphenols have been prepared as candidate coatings for piezoelectric sorption detectors. The liquids have been used as GLC stationary phases, and gas–liquid partition coefficients of a series of solutes have been obtained for these phases. Application of the linear solvation energy equation below has revealed that two particular liquids (8 and 9) possess very large hydrogen bond acidities coupled to rather small hydrogen bond basicities, and hence might be suitable as coatings with selectivity towards solutes that are hydrogen bond bases. One other compound (10) is not suitable as a coating because it is a solid at room temperature, but it has very considerable hydrogen bond acidity, and may be suitable as a novel GLC stationary phase. In the linear solution log K=c+rR2+sπ2H+aα2H+bβ2H+l log L16 energy equation above, K is the gas–liquid partition coefficient for a series of solutes on a given phase, and the explanatory variables R2, π2H, α2H, β2H and log log L16 are solute parameters that we have described before. A term by term analysis of the equation can be used to evaluate quantitatively how specific solute–solvent interactions influence the magnitude of the various log K values.

Enzymatic and gas-liquid chromatographic measurement of D-arabinitol compared.

Journal Article Enzymatic and gas-liquid chromatographic measurement of D-arabinitol compared. Get access K Soyama, K Soyama Dept. of Lab. Med., Kyoto Prefectural Univ. of Med., Japan Search for other works by this author on: Oxford Academic Google Scholar E Ono E Ono Dept. of Lab. Med., Kyoto Prefectural Univ. of Med., Japan Search for other works by this author on: Oxford Academic Google Scholar Clinical Chemistry, Volume 34, Issue 2, 1 February 1988, Page 432, https://doi.org/10.1093/clinchem/34.2.432 Published: 01 February 1988

Midazolam as an Intravenous Induction Agent in the Elderly

Midazolam, the first benzodiazepine derivative with water-soluble salts, was studied as an induction agent in general anesthesia for the elderly. In group 1 (n = 14), 5 or 10 mg oral diazepam was used as premedication, but in group 2 (n = 9), both oral (10 mg dixyrazin as a night-time sedative) and intramuscular (0.01 mg/kg atropine + 1 mg/kg meperidine) premedicants were used. Serum concentrations of benzodiazepines were determined using both gas-liquid chromatographic (unchanged midazolam) and radioreceptor assays (binding equivalents of benzodiazepines plus their active metabolites). In general, midazolam, 0.15 mg/kg, intravenously resulted in smooth induction of anesthesia, although the time required for induction was rather long and a sudden but transient decrease in blood pressure was found in a significant number of patients. The course of anesthesia was otherwise satisfactory. A marked amnesic effect was observed, especially when diazepam was used as premedication. The pharmacokinetic parameters based on gas-liquid chromatographic measurements were quite comparable with those in young, healthy persons published earlier. In both groups, the binding equivalents measured with radioreceptor assay (reflecting total benzodiazepine activity) were higher than the levels of unchanged midazolam determined with gas-liquid chromatography. The relatively low dose of 0.15 mg/kg of midazolam needed for anesthetic induction in the elderly indicates not pharmacokinetic, but pharmacodynamic, alterations in older patients. We conclude that midazolam is a new intravenous induction agent for use in the elderly, but careful titration of the dosage according to the response of the patient is required. Diazepam premedication prior to midazolam causes a marked anterograde amnesic effect.

Gas—liquid chromatography reference method for the assay of urinary creatinine

The gas—liquid chromatographic measurement of urinary creatinine described in this paper employs methylation, the use of a diethylene glycol succinate stationary phase, an internal L-hydroxyproline standard and a temperature of 180°C. The technique, which is specific and reproducible, is shown to be a reference method providing more precise and reliable results than a conventional colorimetric method. In addition, it can be used as a routine method because of its simplicity.

Hydrolysis and excretion of cytoplasmic cholesteryl esters by macrophages: stimulation by high density lipoprotein and other agents

The ability of mouse peritoneal macrophages to hydrolyze and excrete cytoplasmic cholesteryl ester droplets was studied. The macrophages were loaded with cholesteryl esters by incubation with acetylated low density lipoprotein (acetyl-LDL), which is internalized by adsorptive endocytosis. The cholesteryl esters of acetyl-LDL are hydrolyzed within lysosomes and the liberated cholesterol is re-esterified in the cytoplasm where it accumulates as cytoplasmic cholesteryl ester droplets. Hydrolysis and excretion of these stored cholesteryl esters were quantified by gas-liquid chromatographic measurement of the content of free and esterified cholesterol in cells and in medium. After removal of acetyl-LDL from the culture medium, the cytoplasmic cholesteryl esters were rapidly hydrolyzed and large amounts of free cholesterol were excreted from the cells. Hydrolysis and excretion required a cholesterol acceptor in the culture medium. The following agents were shown to be effective as cholesterol acceptors: high density lipoprotein (HDL), whole serum, the density > 1.215 g/ml fraction of whole serum, intact erythrocytes, casein, and thyroglobulin. The following agents did not promote the hydrolysis and excretion of cholesteryl esters under these experimental conditions: LDL, serum albumin, serum gamma-globulins, and phosphatidylcholine/sphingomyelin liposomes. The results indicate that net hydrolysis of cytoplasmic cholesteryl esters in macrophages is coupled to the process of cholesterol excretion and that net hydrolysis does not occur unless an effective cholesterol acceptor is present in the culture medium.-Ho, Y. K., M. S. Brown, and J. L. Goldstein. Hydrolysis and excretion of cytoplasmic cholesteryl esters by macrophages: stimulation by high density lipoprotein and other agents.

Formation constants and enthalpies of reaction from gas-liquid chromatographic measurements

The determination of the formation constants and enthalpies of reaction for four C8 diene-silver ion complexes using gas-liquid chromatography is described.

Gas-liquid chromatographic measurement of lignocaine in small samples of canine myocardium after enzymatic digestion.

A method is described whereby lignocaine can be measured in small samples of canine myocardium. A proteolytic enzyme is used to digest the tissue, and the drug, together with an internal standard, is subsequently extracted into an organic solvent and measured by gas-liquid chromatography. The method is reproducible using tissue samples as small as 50 mg and appears to be suitable for the measurement of a number of drugs in small samples of tissue.

Formation constants and activity coefficients from gas—liquid chromatographic measurements

Formation constants and activity coefficients from gas—liquid chromatographic measurements

Reconciliation of gas-liquid chromatographic and nuclear magnetic resonance measurements for association constants of organic complexes

Reconciliation of gas-liquid chromatographic and nuclear magnetic resonance measurements for association constants of organic complexes

Gas—Liquid Chromatographic Measurement of Guanidino Acids

We present a method for separating and measuring guanidino acids by gas-liquid chromatography. Compared to ion-exchange techniques, this system is faster, more sensitive, requires smaller sample volumes, is independent of colorimetric reactions, and permits simultaneous determination of both amino and guanidino acids. N-Trifluoracetyl-n-butyl esters are formed and then are separated by using a column containing a mixed silicone liquid phase coated on Chromosorb W-HP. Analytical recoveries from plasma ranged from 86 to 112% and were done without prior protein precipitation. Speculations as to the cause of this interference by protein include coprecipitation, protein-binding, and cyclization of the guanidines in the acids used for denaturation. Evidence presented suggests that all three occur: ultrafiltrability is diminished in the presence of protein and nuclear magnetic resonance demonstrates cyclization of some of these esters.

Effect of environmental parameters on bacterial degradation of Bunker C oil, Crude oils, and hydrocarbons.

Mixed microbial cultures, previously enriched on Bunker C fuel oil, grew on and degraded Bunker C fuel oil at temperatures ranging from 5 to 28 C. At 15 C, 41 to 85% of the benzene-soluble components of Bunker C disappeared after incubation for 7 days; at 5 C the values ranged from 21 to 52% after 14 days of incubation. A Nocardia sp. isolated from a culture enriched on Bunker C oil grew on Venezuelan crude oil, Bunker C, hexadecane, and a hydrocarbon mixture at temperatures of 5 and 15 C. The 10-C decrease in temperature resulted in an average 2.2-fold decrease in generation time of the bacteria. Gas-liquid chromatographic measurements of Venezuelan and Arabian crude oils which had been incubated with the Nocardia sp. showed significant degradation of the n-alkane portion and the chromatographically unresolved components of the oils. The concentration of elemental nitrogen required to bring about the disappearance of 1 mg of hexadecane by the Nocardia sp. was 0.5 mg. The results confirm suggestions that the rate of natural biodegradation of oil in marine temperate-to-polar zones is probably limited by low temperatures and phosphorus concentrations, but suggest that the concentrations of nitrogen occurring naturally are probably not rate-limiting factors.