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At least 19 recordsLinked to original sources
PubMed1978

Comparative determination of phenytoin by spectrophotometry, gas chromatography, liquid chromatography, enzyme immunoassay, and radioimmunoassay.

Sera from patients being treated with phenytoin were analyzed for the drug by spectrophotometry, gas chromatography, radioimmunoassay, enzyme immunoassay, and liquid chromatography. The essay values obtained were intercompared statistically. Enzyme immunoassay and liquid chromatography appear to be attractive alternatives to the more traditional methods of spectrophotometry and gas chromatography. Our radioimmunoassay data correlated poorly with results by the four other methods.

Chromatography, Gas↗
PubMed1979

Disopyramide determination by gas chromatography, liquid chromatography, and gas chromatography--mass spectrometry.

Disopyramide is determined in serum by gas chromatography with a nitrogen-selective detector, by liquid chromatography, and by gas chromatography--mass spectrometry. Comparable results are obtained with the three techniques, with a within-run and between-run precision of 5 to 10% (coefficient of variation). Least-squares analysis of data on patients' sera, analyzed first by gas chromatography (y) and then liquid chromatography (x), gave a slope of 1.12; y-intercept, -0.31; standard error of estimate, 0.46; and correlation coefficient, 0.94. Comparison of patients' sera by gas chromatography (y) and then by gas chromatography--mass spectrometry (x) gave a slope of 0.94; y-intercept, 0.42; standard error of estimate, 0.38; and correlation coefficient, 0.97. Interferences observed when using one technique--for example, gas chromatography--can be eliminated by analyzing the sample extract with one of the other techniques.

Chromatography, Gas↗
PubMed1977

Gas-liquid chromatography and liquid chromatography of ethylenethiourea in fresh vegetable crops, fruits, milk, and cooked foods.

The Onley-Yip procedure for determining ethylenethiourea (ETU) in milk and crops was modified to reduce interferences by the ethylenebisdithiocarbamates (EBDCs). A 20 g crop-methanol extract is cleaned up by adsorbing the sample onto Gas-Chrom S. desorbing ETU, and eluting ETU from aluminum oxide with chloroform containing ethanol. ETU is converted to the S-butyl derivative for gas-liquid chromatography (GLC) and flame photometric detection (sulfur mode). For liquid chromatography (LC), ETU is cleaned up on another aluminum oxide column and injected directly. LC and GLC results are confirmed by thin layer chromatography. A cooking procedure based on conversion of EBDCs to ETU is included for surveying crops for possible EBDC content. Recoveries from 8 crops and milk fortified at 0.05 ppm ETU ranged from 73 to 100%.

Animals↗
PubMed1976

The separation, identification, and quantitation of cannabinoids and their tau=butyldimethylsilyl, trimethylsilylacetate, and diethylphosphate derivatives using high-pressure liquid chromatography, gas-liquid chromatography, and mass spectrometry.

Methods for the separation, identification, and quantitation, of cannabinoids present in hashish have been developed. These methods include high-pressure liquid chromatographic and gas-liquid chromatographic separation of cannabinol, delta 9-tetrahydrocannabinol, delta 8-tetrahydrocannabinol, and cannabidiol as well as their tau-butyidimethylsilyl either and trimethylsilylacetate derivatives. The necessity for internal standards; the sensitivity of the HPLC method; and some mass spectral fragmentation pathways for the tau-butyldimethylsily, trimethylsilylacetate, and diethylphosphate derivatives are discussed.

Cannabinoids↗
PubMed1978

[Determination of ketoprofen in plasma using high-performance liquid chromatography. Comparison with gas--liquid chromatography (author's transl)].

A new method of determination of ketoprofen 2-(3-benzoyl phenyl) propionic acid in plasma using high-performance liquid chromatography (HPLC) is described. After extraction by diethyl either in acidic medium, ketoprofen and the internal standard, 2-(4-benzoyl phenyl) butyric acid, are methylated with gaseous diazomethane and their concentrations measured by HPLC using in LiChrosorb Si 60 (5 micrometer) column and dichloromethane-hexane (60:40) as the mobile phase. The absolute retention times of the internal standard and ketoprofen are 11.6 and 12.8 min, respectively. The precision of the methods is +/- 4% and the lower detection limit ranges from 0.06 to 0.10 microgram/ml. The results obtained by HPLC show a very good correlation with those obtained by gas--liquid chromatography. The proposed method is sensitive, reproducible and rapid and very suitable for ketoprofen determination in pharmacokinetic studies.

Chromatography, Gas↗
PubMed1977

Trace analysis of zearalenone and/or zearalanol in animal chow by high pressure liquid chromatography and gas-liquid chromatography.

An analytical method is described for determining residues of the estrogens zearalenone and/or zearalanol in animal chow at levels as low as 10 ppb. The chow is extracted with methanol and cleaned up by a 3-step procedure employing a Sephadex LH-20 column, liquid-liquid partitioning at pH 13 and 8.3, and a silica gel column. Residues of the 2 compounds, separated on silica gel, are assayed by using high pressure liquid chromatography with ultraviolet detection. Additional data are also included concerning p-values of the compounds in several solvent systems, Rf values from thin layer chromatography with 9 solvent systems, solubilities in 3 solvents, and a procedure for preparing their pentafluoropropionyl derivatives for analysis by electron capture gas-liquid chromatography.

Animal Feed↗
PubMed1977

Analysis of polychlorinated biphenyls by high-performance liquid chromatography and capillary gas-liquid chromatography.

Seventy fractions were obtained by vacuum distillation of a PCB mixture containing 42% of chlorine. Four of these fractions were chosen, the composition of which covered the whole of the observed region, and analysed by means of high-performance liquid chromatography (HPLC) on silica gel using n-pentane as the mobile phase and capillary gas-liquid chromatography (GLC) using OV-101 and Carbowax 20M as stationary phases at 200 degrees C. The chosen distillation fractions were further prepared by HPLC, each yielding 10-14 samples. Individual PCB standards and all samples were analysed by HPLC and capillary GLC. These procedures permitted the identification of those compounds which are eluted simultaneously under the conditions used in either HPLC or capillary GLC alone.

Chromatography, Gas↗
PubMed1979

Analysis of the anti-coccidial drug, halofunginone, in chicken feed using gas-liquid chromatography and high-performance liquid chromatography.

Methods are described for the analysis of the anti-coccidial drug, halofuginone, at concentrations of 3 ppm in chicken feed, using gas-liquid chromatography and high-performance liquid chromatography. Both methods are based on ethyl acetate extraction, partition into hydrochloric acid and purification and concentration using XAD-2 column chromatography. The precision and accuracy of both methods is given.

Animal Feed↗
PubMed1976

Application of gas-liquid chromatography and high-performance liquid chromatography to the analysis of trace amounts of salicylic acid, acetylsalicylic anhydride and acetylsalicylsalicylic acid in aspirin samples and aspirin formulations.

The gas-liquid chromatographic (GLC) determination of salicylic acid (SA) in 12 commercial acetylsalicylic acid (aspirin, ASA) samples and 12 ASA formulations is reported. The GLC determination of SA as an impurity in ASA, utilising methylation with methyl iodide in the presence of potassium carbonate, requires a column chromatographic separation of SA prior to derivatization. Trace amounts of SA in ASA have also been determined by high-performance liquid chromatography (HPLC) on a Sil-X-I adsorption column using light petroleum-ethyl acetate-acetic acid as the mobile phase. Acetylsalicylic anhydride (ASN) and acetylsalicylsalicylic acid (ASSA) were determined by HPLC on a reversed-phase C18 column with water-methanol mixtures as the mobile phase. GLC was also applied to the determination of ASN as an impurity in ASA formulations.

Anhydrides↗
PubMed1979

Analysis for diazepam and nordiazepam by electron-capture gas chromatography and by liquid chromatography.

We describe the use of electron-capture gas chromatography or reversed-phase "high-performance" liquid chromatography for concurrent analysis for diazepam and nordiazepam in serum. In the gas-chromatographic analysis our use of a new chemically deactivated stationary liquid phase, SP 2250-DB (Supelco, Inc.), resulted in improved chromatographic sensitivity and peak symmetry for the two benzodiazepines as compared to that obtained with either OV-17or OV-1 phases. Steady-state concentrations of diazepam and nordiazepam in serum as determined by gas-liquid chromatography correlated closely with those found by liquid-liquid chromatography.

Chromatography, Gas↗
PubMed1975

Gas-liquid chromatography and gas-liquid chromatography combined with mass spectrometry of a butyl ester formulation of (2,4-dichlorophenoxy) acetic acid.

A method is presented for the analysis of (2,4-dichlorophenoxy)acetic acid (2,4-D) in commercial formulations, together with concurrent detection and quantitation of related compounds. The method is based on direct gas-liquid chromatographic (GLC) analysis of the formulation to estimate the various esters present, and on an analysis of the total 2,4-D present involving a prior cleanup, alkaline hydrolysis, acidification and n-butylation steps. This procedure also quantitates any other related acids or phenols present. A step which would extract dioxin impurities is also included. The method was checked by the accepted acid-base estimation of 2,4-D content, GLC, and by subjecting radioactive-labelled herbicide to the above procedures.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1978

Determination of zearalenone in cornflakes and other corn-based foods by thin layer chromatography, high pressure liquid chromatography, and gas-liquid chromatography/high resolution mass spectrometry.

A simple cleanup procedure based on pH adjustments was used to obtain extracts of corn foods. The method gave good recoveries of zearalenone determined by thin layer chromatography (TLC) and high pressure liquid chromatography (HPLC). As little as 5 ng zearalenone was detected by TLC, using Fast Violet B Salt as the spray reagent; the lower limit of detection in cornflakes was about 20 microgram/kg. With HPLC on Spherisorb silica (5 micrometer) and detection by fluorescence at an excitation maximum of 310 nm as little as 5 microgram zearalenone/kg cornflakes could be determined. While the TLC method was also applicable to corn chips, cornmeal, popcorn, and frozen corn, an interference was observed in HPLC of the latter 3 products. This interference was separated from zearalenone by adding a second HPLC analytical column (Spherisorb ODS). Gas-liquid chromatography coupled with mass spectrometric single ion monitoring at high resolution, although of limited availability, was shown to be the most sensitive and selective method for determining zearalenone in corn foods. The natural occurrence of zearalenone in a sample of cornflakes (13-20 microgram/kg) was demonstrated by all 3 detection procedures.

Chromatography, Gas↗
PubMed1979

Rapid differentiation of Streptomyces from Nocardia by liquid chromatography.

A liquid chromatographic method is described for analysis of aerobic actinomycetes for isomers of diaminopimelic acid. One or two colonies of organism were hydrolyzed with 6.0 mol of HCl per liter at 121 degrees C for 15 min. The hydrolysate was neutralized and buffered with an NaOH solution (3 mol/liter) containing 0.15 mol of sodium borate per liter. Precolumn derivatization with dansyl chloride was used to form a fluorescent product for detection. Analysis was performed by reversed-phase, ion-pair chromatography. The L-diaminopimelic acid isomer was detected in all 10 strains of Streptomyces tested, and the meso-diaminopimelic acid isomer was detected in all 10 strains of Nocardia tested. Liquid chromatography was compared simultaneously with thin-layer chromatography in the analysis of three strains of aerobic actinomycetes. Liquid chromatography required less growth of the organisms, and analysis was completed within 1 h, compared with the 3 to 5 days required by thin-layer chromatography.

Aerobiosis↗