Biomedical subjects

C L Flurer

Publications and source records attributed to C L Flurer.

12 recordsLinked to original sources

PubMed2001

Analysis of antibiotics by capillary electrophoresis.

This article reviews recent developments in the characterization of antibiotics. Many capillary electrophoretic techniques have been utilized in their analyses, addressing various aspects of quantifying, profiling and monitoring. Sensitive electrochemical and laser-induced fluorescence detection systems have been utilized, demonstrating trace level determinations in clinical settings and in environmental samples. Different sample introduction methods have been explored, enhancing detection sensitivity, or reducing or eliminating sample manipulation prior to injection.

Anti-Bacterial Agents↗

PubMed2000

Detection of adulteration of locust bean gum with guar gum by capillary electrophoresis and polarized light microscopy.

Capillary electrophoresis (CE) and polarized light microscopy (PLM) were utilized in the detection of the adulteration of locust bean gum with guar gum. For CE analyses, standards of locust bean and guar gums were extracted with 30% CH3CN, removing the residual proteins from the gum matrix. A 8.75 mM NaH2PO4-20.6 mM Na2B4O7 buffer, pH 9, was used to separate these proteins and to identify marker proteins that were present in the guar gum. These markers did not co-migrate with components in the extracts of mechanically processed locust bean gum, and are used as indicators of adulteration. Using PLM with toluidine blue and iodine staining techniques, unadulterated locust bean gum samples were distinguished from mixed samples through the differential staining of components in locust bean versus guar and tara gums. These experiments in the use of CE and PLM provide orthogonal and complementary methods for the verification of 'true' positives and the elimination of 'false' positives.

Electrophoresis, Capillary↗

PubMed2000

Characterization of galactomannans by capillary electrophoresis.

Capillary electrophoresis (CE) was utilized in the characterization of various galactomannans. Standards of gums were extracted with 50% CH3CN to remove the residual proteins from the gum matrix. Separation buffers were optimized with respect to pH, buffer concentration and presence of sodium dodecyl sulphate, yielding protein profiles from which the desired information could be obtained. Examples are given of the profiles generated by various gums and gum blends to aid in the verification of component presence, and to demonstrate levels of adulteration detectable under the buffer conditions used.

Cassia↗

PubMed1999

Analysis of antibiotics by capillary electrophoresis.

The broad category of antibiotics encompasses some of the most widely prescribed pharmaceuticals in the world. As is the case with any pharmaceutical, an antibiotic must be characterized in terms of its potency and the presence and quantity of impurities. Additionally, any residue or metabolite that may be present as a result of its use must be monitored. Many capillary electrophoretic techniques have been utilized in the analysis of antibiotics, addressing the various aspects of quantifying, profiling, and monitoring. Some of the more recent applications are summarized in this review article.

Anti-Bacterial Agents↗

PubMed1997

Analysis of antibiotics by capillary electrophoresis.

The broad category of antibiotics encompasses some of the most widely prescribed pharmaceuticals in the world. As is the case with any pharmaceutical, an antibiotic must be characterized in terms of its potency or activity, and the presence and quantity of impurities. Additionally, any residue or metabolite that may be present as a result of its use must be monitored. Many capillary electrophoretic techniques have been utilized in the analysis of antibiotics, addressing the various aspects of their quantitation, profiling, and monitoring. Some of the more recent applications are summarized in this review article.

Anti-Bacterial Agents↗

PubMed1996

Analysis of macrolide antibiotics by capillary electrophoresis.

Capillary electrophoresis was utilized in the study of the macrolide antibiotics (i.e. pharmaceutical glycoconjugates) clarithromycin, erythromycin, oleandomycin, troleandomycin, and spiramycin. In order to assist in analyte solubilization, two buffer systems using acetonitrile were developed. The first system involved 30 mM sodium cholate and 20% acetonitrile in 80 mM sodium phosphate, pH 6. This buffer permitted the baseline resolution of all five glycoconjugated antibiotics. In addition, erythromycin was separated from its derivatives estolate and ethylsuccinate. In the absence of surfactants, a higher acetonitrile quantity, 65%, was used in the second buffer system, with 35 mM sodium phosphate, pH 6. Selectivity between oleandomycin and clarithromycin was reversed in this system compared to the cholate buffer, indicating solute interaction with the cholate micelles in the previous system. Calibration linearity and detection sensitivity were improved in the high acetonitrile buffer, due to decreased background absorbance. It was demonstrated that both buffer systems can be utilized for the visualization of minor components that may be present in bulk pharmaceuticals.

Acetonitriles↗

PubMed1995

Determination of ephedrine compounds in nutritional supplements by cyclodextrin-modified capillary electrophoresis.

Capillary electrophoresis was utilized for the separation, identification, and quantitation of ten stereoisomers in the ephedrine family. Chiral discrimination was accomplished through the use of hydroxypropyl-beta-cyclodextrin, and separation was enhanced at pH 2 in the presence of tetramethylammonium chloride and sodium dodecyl sulfate. Calibration plots of the ephedrines were linear over the range 4-100 micrograms/ml. This method was used in the analysis of nutritional supplements that contain Ma Huang, a Chinese herbal preparation that is made from plants in the genus Ephedra.

Cyclodextrins↗

PubMed1995

The analysis of aminoglycoside antibiotics by capillary electrophoresis.

The analyses of aminoglycoside antibiotics by capillary electrophoresis utilizing borate complexation and direct UV detection are discussed. Twelve aminoglycosides were studied and separated to demonstrate identification capabilities, with migration time RSDs from 0.21 to 0.44% (n = 6) for individual components. This buffer system permitted the detection of minor impurities such as precursors or closely related fermentation products. Quantification of dihydrostreptomycin and streptomycin was accomplished in 160 mM sodium tetraborate decahydrate with linearity over the range 0.050-1.0 mg ml-1. Determination of the purity of bulk dihydrostreptomycin was possible by the addition of the cationic surfactant myristyltrimethylammonium bromide. This reversed the electroosmotic flow, thereby reversing the migration order, and causing the streptomycin impurity to migrate before the dihydrostreptomycin main peak. Quantification was also demonstrated with the closely related compounds amikacin, bekanamycin, kanamycin A, and tobramycin, using sisomicin as an internal standard. The reproducibility of the method was typically 2-3% over 1 day, and 2% day-to-day. These studies illustrate the use of capillary electrophoresis for the identification and quantification of selected aminoglycosides as potential alternative methods to the assays given by the US Pharmacopeia.

Anti-Bacterial Agents↗

PubMed1994

Chemical profiling of pharmaceuticals by capillary electrophoresis in the determination of drug origin.

Capillary electrophoresis has been utilized to detect trace components in bulk pharmaceutical products, with emphasis on the identification of differences among manufacturers that can be used for source verification in suspect/counterfeit cases. Micellar electrokinetic capillary chromatography with sodium dodecyl sulfate was used in the analyses of beta-lactam antibiotics. The aminoglycoside clindamycin phosphate and the macrolide erythromycin stearate were analyzed using borate buffers with direct UV detection. Methyl-beta-cyclodextrin was used as a buffer additive in the erythromycin studies. Determination of product potency using peak area ratios has been demonstrated for ampicillin and clindamycin phosphate.

Anti-Bacterial Agents↗

PubMed1994

Quantitation of gentamicin sulfate in injectable solutions by capillary electrophoresis.

The results presented in this communication establish the use of capillary electrophoresis as a tool in the analysis of injectable solutions containing the antibiotic complex gentamicin sulfate. The utilization of a borate buffer leads to the separation of the individual components and their visualization by direct UV detection. This rapid and straightforward procedure yields qualitative and quantitative information simultaneously, and could be utilized as an alternative to the multiple assays required by current US Pharmacopoeia protocols.

Electrophoresis↗

PubMed1993

Dual microcolumn immunoaffinity liquid chromatography: an analytical application to human plasma proteins.

Dual-column microcolumn immunoaffinity chromatography was accomplished by coupling immunoaffinity (IAC) and reversed-phase high-performance liquid chromatography (RP-HPLC) analysis columns. The IAC support was prepared by hydrophobically adsorbing the appropriate antibody onto an octyl silica-based stationary phase contained in a 250-microns-l.d. fused-silica microcolumn. Once the antigen was captured, the antigen-subtracted human plasma could be sent to the RP-HPLC microcolumn for plasma profiling. The antigen was quantitated by desorbing it from the IAC column and transferring it to the RP-HPLC system. Human plasma profiles were generated after removal of albumin, and transferrin and alpha 1-antitrypsin were quantitated with nanogram sensitivity. All analyses were accomplished with less than 1 microL of human plasma.

Albumins↗

PubMed1988

Separation of proteins by microcolumn liquid chromatography based on the reversed-phase and size-exclusion principles.

Slurry-packed fused-silica microcolumns of 250 micron I.D., are characterized for use in high-performance liquid chromatographic studies of proteins. The present work utilizes the reversed-phase and size-exclusion chromatographic modes for the separation of standard protein mixtures. A 5-micron, 300-A octyl material is utilized for the reversed-phase studies, and the size-exclusion studies are accomplished with 5-micron diol material of 60-, 100- and 300-A pore sizes. Column efficiency and packing reproducibility, as well as sample capacity in a micropreparative mode, are discussed. In addition, the inherent mass sensitivity of a microcolumn liquid chromatography system as applied to protein detection is demonstrated.

Chromatography, Gel↗