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At least 991 records · Page 55Linked to original sources
PubMed1976

Protein chromatography on adsorbents with hydrophobic and ionic groups. Chromatography of dodecyl sulphate-solubilized proteins of the human erythrocyte membrane on N-(3-carboxypropionyl)aminodecyl-sepharose.

Human erythrocyte 'ghosts' were solubilized in 0.5% (w/v) sodium dodecyl sulphate at pH 4.0(I = 0.012 mol/I). At a loading of 1-2 mg of protein/ml of column volume, all of membrane proteins were adsorbed to a column of CPAD [N-(3-carboxypropionyl)-aminodecyl]-Sepharose at pH 4.0 (I = 0-012 mol/1) and room temperature (22 degrees C). Many proteins were subsequently desorbed by raising the pH or by including sodium dodecyl sulphate continuously in the eluting buffer. Experiments with a series of adsorbents homologous with CPAD-Sepharose, in which the length of the hydrocarbon chain was varied, provided strong evidence of hydrophobic interactions, in addition to ionic interactions, in the binding of these proteins to CPAD-Sepharose. Elution with increasing-pH gradients at different concentrations of sodium dodecyl sulphate showed that glycophorin (the major sialoglycoprotein) was eluted in the void volume, at recoveries close to 100%, when the detergent concentration was greater than or equal to 0.3% (w/v). Protein E, the major protein, was desorbed late in the pH gradient even at a high (0.5%, w/v) concentration of the detergent, and was always incompletely desorbed, the maximum recovery recorded being 40%. Spectrin (the high-molecular-weight polypeptide pair) did not behave in a well-defined manner, and was found widely distributed among the effluent fractions under all the conditions that were tested.

Alanine↗
PubMed1990

High-performance liquid chromatography of proteins on deformed nonporous agarose beads. Affinity chromatography of dehydrogenases based on cibacron blue-derivatized agarose.

Nonporous agarose beads, prepared by shrinkage and cross-linking in organic solvents, were derivatized with Cibacron Blue F3G-A. A compressed bed of these beads was used for purification of dehydrogenases (glucose-6-phosphate dehydrogenase, lactate dehydrogenase and alcohol dehydrogenase). The chromatographic conditions for the purification of glucose-6-phosphate dehydrogenase were optimized by varying the pH of the buffer; the concentrations of eluting agents, i.e. NADP (specific elution) and sodium chloride (nonspecific elution); flow rate; residence time of the protein on the column bed; and protein load. Specific elution with NADP (2 mM in 0.025 M Tris-HCl, pH 8.0) gave the highest recovery (140%) and highest purification factor (200-fold) of the enzyme. The ability of the compressed bed of nonporous agarose beads to tolerate high flow rates was essential, since the recovery of the enzyme activity increased with an increase in flow rate.

Adsorption↗
PubMed2005

Application of accelerated solvent extraction followed by gel performance chromatography and high-performance liquid chromatography for the determination of polycyclic aromatic hydrocarbons in mussel tissue.

Accelerated solvent extraction (ASE) has been evaluated as a fast alternative to methanolic saponification for the extraction of 12 polycyclic aromatic hydrocarbons (PAHs) from mussel tissue. Several solvent systems and different operating conditions were investigated. The mixture dichloromethane-acetone (1:1, v/v) gave the best recoveries at 125 degrees C and 1500 psi, in a total time of 10 min. No yield difference was found between freeze-drying (Fd) or drying the wet mussel with diatomaceous earth (Ded) prior to extraction. The ASE method was validated using the standard reference material SRM 2977, a freeze-dried mussel tissue with naturally present organic contaminants. The performance characteristics of the ASE method (trueness: 70-110%; precision: 4-14% and limit of quantification (LOQ): 0.1-0.25 microg/kg) meet the criteria established by the European Union for quantitative methods of analysis for official control of organic residues and contaminants. ASE provides a 24 times faster extraction than MSE and reduces 12 times the volume of solvent required.

Animals↗
PubMed1976

Determination and identification of polycyclic aromatic hydrocarbons in smoked and charcoal-broiled food products by high pressure liquid chromatography and gas chromatography.

A high pressure liquid chromatographic procedure has been developed and applied to the analysis of polycyclic aromatic hydrocarbons (PAH's) in 70 samples of smoked food products commercially available in Canada, and in 6 charcoal broiled meats. In some cases a gas-liquid chromatographic procedure was used as a confirmatory technique. In the commercial samples PAH's were detected in approx. 70% of the samples. Total PAH's ranged from 0-141 ppb and individual PAH's from 0-38 ppb. With the charcoal-broiled samples, total PAH's and individual PAH's ranged from 0-164 ppb and 0-60 ppb respectively. These levels are similar to those observed in other countries.

Canada↗
PubMed2006

Characterization of laboratory simulated road paving-like asphalt by high-performance liquid chromatography and gas chromatography-mass spectrometry.

Prolonged, extensive exposure to asphalt fume has been associated with several adverse health effects. Inhaled polycyclic aromatic hydrocarbons (PAHs) from asphalt fume exposure are of concern. The objective of this study was to characterize both qualitative and quantitative differences between fumes generated at 150 degrees C and 180 degrees C using a well-controlled laboratory road paving fume generation system. Fumes were characterized by total volatile and particulate concentration, simulated boiling point profile, and specific PAH content. The mean concentrations of the volatile fractions generated at 180 degrees C and 150 degrees C were 23.3 mg/m3 and 11.2 mg/m3, respectively, demonstrating a statistically significant shift in concentration. The mean concentrations of the particulate fractions generated at 180 degrees C and 150 degrees C were 42.4 mg/m3 and 28.0 mg/m3, respectively. The simulated boiling point profile did not show a significant qualitative difference between the fumes generated at the two temperatures. Naphthalene, acenaphthene, fluorene, phenanthrene, fluoranthene, pyrene, and chrysene were identified and quantified from the fumes.

Air Pollutants, Occupational↗
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↗
PubMed2001

Measurement of 8-hydroxy-2'-deoxyguanosine in DNA by high-performance liquid chromatography-mass spectrometry: comparison with measurement by gas chromatography-mass spectrometry.

Measurement of 8-hydroxy-2'-deoxyguanosine (8-OH-dGuo) in DNA by high-performance liquid chromatography/mass spectrometry (LC/MS) was studied. A methodology was developed for separation by LC of 8-OH-dGuo from intact and modified nucleosides in DNA hydrolyzed by a combination of four enzymes: DNase I, phosphodiesterases I and II and alkaline phosphatase. The atmospheric pressure ionization-electrospray process was used for mass spectral measurements. A stable isotope-labeled analog of 8-OH-dGuo was used as an internal standard for quantification by isotope-dilution MS (IDMS). Results showed that LC/IDMS with selected ion-monitoring (SIM) is well suited for identification and quantification of 8-OH-dGuo in DNA at background levels and in damaged DNA. The sensitivity level of LC/IDMS-SIM was found to be comparable to that reported previously using LC-tandem MS (LC/MS/MS). It was found that approximately five lesions per 10(6) DNA bases can be detected using amounts of DNA as low as 2 microgram. The results also suggest that this lesion may be quantified in DNA at levels of one lesion per 10(6) DNA bases, or even lower, when more DNA is used. Up to 50 microgram of DNA per injection were used without adversely affecting the measurements. Gas chromatography/isotope-dilution MS with selected-ion monitoring (GC/IDMS-SIM) was also used to measure this compound in DNA following its removal from DNA by acidic hydrolysis or by hydrolysis with Escherichia coli Fpg protein. The background levels obtained by LC/IDMS-SIM and GC/IDMS-SIM were almost identical. Calf thymus DNA and DNA isolated from cultured HeLa cells were used for this purpose. This indicates that these two techniques can provide similar results in terms of the measurement of 8-OH-dGuo in DNA. In addition, DNA in buffered aqueous solution was damaged by ionizing radiation at different radiation doses and analyzed by LC/IDMS-SIM and GC/IDMS-SIM. Again, similar results were obtained by the two techniques. The sensitivity of GC/MS-SIM for 7,8-dihydro-8-oxoguanine was also examined and found to be much greater than that of LC/MS-SIM and the reported sensitivity of LC/MS/MS for 8-OH-dGuo. Taken together, the results unequivocally show that LC/IDMS-SIM is well suited for sensitive and accurate measurement of 8-OH-dGuo in DNA and that both LC/IDMS-SIM and GC/IDMS-SIM can provide similar results.

8-Hydroxy-2'-Deoxyguanosine↗