Showing papers in "Journal of Chromatographic Science in 1977"
TL;DR: The use of novel polysiloxanes as stationary phase carrying chiral groups enables the separation of most amino acid enantiomers in a much shorter time than ever reported previously.
Abstract: The use of novel polysiloxanes as stationary phase carrying chiral groups enables the separation of most amino acid enantiomers in a much shorter time than ever reported previously. Phases of this type exhibit very low volatility and high thermal stability and may be used in routine analysis with open tubular columns ant temperatures of at least 175 degrees C. Most protein amino acids are separated in a temperature program between 90 and 175 degrees C, thus obviating the need for multiple injections. Resolution factors are somewhat lower than those of other diamide phases containing the L-valine t-butyl-amide group, but are sufficient for resolution of almost all protein amino acid enantiomers.
509 citations
333 citations
310 citations
TL;DR: Computer simulation studies demonstrated that serious errors can result from calculating column plate count with non-Gaussian peaks and the maximum allowable peak tailing is suggested and a new method for quantitating peak skew is proposed.
Abstract: Chromatographic resolution and analysis accuracy can be seriously affected by broadening of very sharp bands associated with both high-performance size-exclusion chromatography and other liquid chromatography methods using less than 5 micron particles. The effect on column plate count by extra-column band broadening from injection systems, detectors, connectors and "guard" columns is discussed and exemplified with experimental data. The special cases of tailing and doublet peaks for a single species are investigated. These effects are eliminated by a special sample injection technique. Computer simulation studies demonstrated that serious errors can result from calculating column plate count with non-Gaussian peaks. The maximum allowable peak tailing is suggested and a new method for quantitating peak skew is proposed.
291 citations
TL;DR: The samples were concentrated and analyzed by quantitative, reproducible and sensitive techniques which resulted in well-defined composite compositional and occurrence profiles of the organic constituents present in normal expired air.
Abstract: Expired air samples have been collected from a carefully selected population of normal healthy human subjects under controlled experimental conditions. The samples were concentrated and analyzed by quantitative, reproducible and sensitive techniques which resulted in well-defined composite compositional and occurrence profiles of the organic constituents present in normal expired air. The composite profiles provide valuable baseline information upon which suitable correlation studies may be advanced toward the use of human expired air for diagnostic purposes.
156 citations
155 citations
150 citations
TL;DR: Tri-octyl-amine-freon solutions can be used for the extraction of the acid from the solution if the concentration of the amine is carefully controlled.
Abstract: In preparing nucleotide extracts for HPLC analysis using microparticle, chemically bonded packings, tri-octyl-amine-freon solutions can be used for the extraction of the acid from the solution if the concentration of the amine is carefully controlled.
125 citations
TL;DR: It was found that seven vitamins could be resolved from a multivitamin mixture in a single analysis in several solvent systems with the total time for the analyses being always less than 40 min.
Abstract: Resolution of the water-soluble vitamins--pyridoxin, riboflavin, niacinamide, vitamin B12, thiamin, ascorbic acid, niacin and folic acid--by high pressure liquid chromatography was examined on two bonded-phase columns, muBondapak C18 and muBondapak NH2. The effect on the retention times of individual vitamins and the separation of a multivitamin sample was determined using varying proportions of water/methanol as the eluting solvent and by addition of various salts, buffer solutions and PIC reagents to the water/methanol. Each vitamin was able to be eluted satisfactorily from muBondapak C18. It was found that seven vitamins could be resolved from a multivitamin mixture in a single analysis in several solvent systems with the total time for the analyses being always less than 40 min. With muBondapak NH2, all the vitamins except folic acid were eluted and six vitamins could be resolved from a mixture in a single analysis. The speed of analysis was greater with muBondapak NH2 with all compounds eluted in 15 min and the peaks were sharper. The order of elution was essentially the reverse of that obtained with muBondapak C18.
82 citations
70 citations
TL;DR: The experiments showed that amino acids at the picomole level could be reliably analyzed with the system and gave greatly improved thermal stability compared with a previously used packed column.
Abstract: A glass open tubular (capillary) column together with a nitrogen-selective detector were evaluated for the analysis of amino acids by gas chromatography. Test samples included normal and abnormal human sera and urine and several hydrolysates of pure proteins. Amino acids in the biological samples were isolated by ion exchange pretreatment and derivatized to the n-propyl, N-acetyl derivatives. Protein hydrolysates were derivatized without pretreatment. Compared with a flame ionization detector, the nitrogen-selective detector gave a sensitivity enhancement of 80x-180x for the amino acid derivatives, depending on the particular amino acid. Long-term stability of the detector was excellent. Reproducibility studies gave a long-term precision of about 6% for serum or urine samples while a precision of 5% was obtainable on a day-to-day basis when analyzing protein hydrolyzates. The experiments showed that amino acids at the picomole level could be reliably analyzed with the system. The open tubular column coated with a mixture of Carbowax 20M and Silar 5 CP and having a very thin liquid phase film gave greatly improved thermal stability compared with a previously used packed column.
TL;DR: Experimental results using a preparative LC unit with columns of 57 mm ID and a solvent delivery system delivering up to 500 ml/min showed the success of preparative fractionation as mentioned in this paper.
Abstract: Experimental results using a preparative LC unit with columns of 57 mm ID and a solvent delivery system delivering up to 500 ml/min showed the success of preparative fractionation. The results obtained in the analysis of the preparative fractions are illustrated. (JSR)
TL;DR: The dinitrophenylhydrazone derivative is extracted with chloroform and concentrated and the residue in methylene chloride is separated and analyzed by high performance liquid chromatography.
Abstract: Formaldehyde in tobacco smoke is allowed to react with 2,4-dinitrophenylhydrazine to form the dinitrophenylhydrazone. This derivative is extracted with chloroform and concentrated. The residue in methylene chloride is separated and analyzed by high performance liquid chromatography. A column packed with 10-micron silica is used for separation. The internal standard is triphenylene. This method can also be used for the analysis of other carbonyl compounds in tobacco smoke that react to form hydrazone derivatives.
TL;DR: Fast, efficient liquid chromatographic separations of aza-arenes were obtained using both, reversed-phase, and adsorbent packings, and an application to an air pollution problem demonstrates the usefulness of this approach.
Abstract: Fast, efficient liquid chromatographic separations of aza-arenes were obtained using both, reversed-phase, and adsorbent packings. Aza-arenes with 2-5 rings are separated within 20 minutes. Sample recovery is quantitative and permits subsequent uv and fluorescence spectrophotometric identifications. The detection limit for most aza-arenes was 1 ng with a 254-nm uv detector. An application to an air pollution problem demonstrates the usefulness of this approach.
TL;DR: High-performance reverse-phase liquid chromatographic data on 28 corticoids and related steroid analogs, plus methyl and propyl parabens, are presented and chromatograms showing the separations of four steroids plus methyland propylParabens obtained on each of the three columns are presented.
Abstract: High-performance reverse-phase liquid chromatographic data on 28 corticoids and related steroid analogs, plus methyl and propyl parabens, are presented. Retention values, relative to acetone, are reported for each steroid on Bondapak Phenyl/Corasil, Bondapak C18/Corasil, and micro(micron) Bondapak C18 columns, and methanol/water or acetonitrile/water mobile phases. Ultraviolet detector response data for four of the steroids and calculated efficiencies for the three different reverse-phase columns are given. Chromatograms showing the separations of four steroids plus methyl and propyl parabens obtained on each of the three columns are also presented.
TL;DR: A high pressure liquid chromatographic assay has been developed for the separation and quantitation of theophylline and its metabolites, theobromine, and dyphylline in biological fluids, viz. human serum, urine, and saliva.
Abstract: A high pressure liquid chromatographic assay has been developed for the separation and quantitation of theophylline and its metabolites (1-methyl uric acid, 3-methyl xanthine, and 1,3-dimethyl uric acid), theobromine, and dyphylline in biological fluids, viz. human serum, urine, and saliva. The serum has been rendered protein-free by passage through a filter with a nominal molecular weight limit of 10,000. The filtrate is injected onto a reverse-phase column and the separation achieved by utilizing a polar mobile phase and dyphylline (dihydroxypropyl theophylline) as the internal standard. The results for two normal subjects are included to illustrate the applicability of the technique.
LGC1
TL;DR: In this paper, the retention index and relative retention were determined for trimethylsilyl esters/ethers of approximately 170 acids and lactones for silicone stationary phases OV-1 (methyl), OV17 (50% phenyl), and QF-1(50% trifluoropropyl).
Abstract: Retention index and relative retention were determined for trimethylsilyl esters/ethers of approximately 170 acids and lactones. The structural categories studied were aldonic (hydroxy monocarboxylic) acids, aldaric (hydroxy dicarboxylic) acids, non - carbohydrate (mainly dicarboxylic) acids, and lactones of aldonic acids. Data are given for the silicone stationary phases OV-1 (methyl), OV-17 (50% phenyl) and QF-1 (50% trifluoropropyl). Diagrams of the retention index on the non-polar phase versus the increase in the retention index on either of the other phases are useful for qualitative analysis. The dependence of retention on structure is interpreted in terms of non-polar and polar interactions between solute and stationary phase. Structural units of the solutes are attributed retention index increments which permit predictions of retention from structure or structure from retention. The reference retention index data can be used in
temperature - programmed analalysis if retentions are measured as methylene unit (MU) values. Differences between the retention index and MU concepts are discussed.
TL;DR: The results of a survey of derivatization techniques involving several substituted anilines are presented, and a rationale is presented for the preliminary selection of a particular derivative for application of the analysis of aniline metabolites in urine.
Abstract: A number of amines have been shown to result from metabolism of various pesticides. From an epidemiological standpoint, it may be possible to monitor human exposure to these pesticides through the excretion of their corresponding amines in urine. An investigation has been initiated to develop and apply methods of analysis of amines in human urine. The results of a survey of derivatization techniques involving several substituted anilines are presented. These include conditions for derivatization, utilizing a number of halo- and nitro- substituted reagents; electron capture and gas chromatographic properties of the derivatives; and stability of the derivatives to extraction and column chromatography for purposes of separation and cleanup. The recoveries of anilines from spiked water and urine samples at the 1.0 ppm and 0.1 ppm levels were between 85 and 90%. The advantages and disadvantages of the various derivatives and techniques are discussed and a rationale is presented for the preliminary selection of a particular derivative for application of the analysis of aniline metabolites in urine.
IBM1