摘要:

A rapid, simple and specific gas chromatographic method has been developed to measure the differentiating agent hexamethylene bisacetamide (HMBA) in biological samples. Addition of a homolog as an internal standard, ultrafiltration and then direct packed column GC-FID analysis of the ultrafiltrate gives a detection limit of less than 50 μg/ml (0.25 mM) for HMBA in plasma or urine. Ultrafiltration is quantitative and assay precision is better than 4.3% for the 1–5 mM range. This method has been applied to determine the bolus dose pharmacokinetics and disposition of HMBA in a single small animal such as a rat. The developed assay should be suitable for therapeutic monitoring of human patients undergoing HMBA treatment.

ISSN:0003-2719    

DOI:10.1080/00032718508069099

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Vanillin reacts with methyldopa and noradrenaline in alkaline medium to form a pink colour which could be measured at 420 nm. Based on this reaction, a colorimetric method for determination of both sympathomimetic amines was established. A linear relationship was observed in the range from 0.12 to 1.44 mg methyldopa and from 0.085 to 1.854 mg noradrenaline.

ISSN:0003-2719    

DOI:10.1080/00032718508069100

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A highly reproducible ion-pair reverse-phase high performance liquid chromatographic assay for cefmenoxime in human serum has been developed. A simple sample cleanup procedure is employed. Cefoxitin is the internal standard and separation is achieved using a C-18 μ-Bondapak column. The mobile phase consists of 20% acetonitrile and 80% 0.05 M ammonium acetate buffer containing 0.005 M tetrabutylammonium hydrogen sulphate as the ion-pair agent. Samples are quantitated by UV detector at 254 nm and 0.02 aufs with an assay sensitivity of 0.625 μg/ml. The method has been successfully applied in a clinical setting.

ISSN:0003-2719    

DOI:10.1080/00032718508069101

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The voltammetric behavior and measurement of nicardipine at the glassy carbon, carbon paste and hanging mercury drop electrodes are discussed. Cyclic voltammetry is used to elucidate the redox mechanism. Nicardipine is shown to adsorb on carbon electrodes, with the surface species retaining its electroactive characteristics. The adsorptive accumulation serves as a preconcentration step which improves the voltammetric measurement with respect to selectivity and sensitivity. Coupling this with a medium-exchange step eliminates interferences due to solution-phase electroactive species and permits direct measurement in urine. The inherent sensitivity of differential pulse voltammetry at the mercury electrode permits convenient measurement at the submicromolar level, with detection limit of 2 × 10−8M. Amperometric detection for a flow injection system is illustrated.

ISSN:0003-2719    

DOI:10.1080/00032718508069102

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A simple and sensitive liquid chromatographic assay procedure using a fluorescence detector for the quantitative determination of verapamil in plasma without extraction was developed. After precipitating the protein with acetonitrile, the resulting supernatant liquid was injected onto the column for analysis. Chromatographic separation was achieved on C18reversed phase column and the eluting solvent was the isocratic mixture of methanol, acetonitrile and pH 3.0 glycine buffer (1:4:5). With this mobile phase the drug and its internal standard were well separated from the interference of the plasma sample. The average recovery of verapamil from 3 replicate samples of different concentration (100–600 ng/mL) were 95.5 ± 5.68%. The minimum amount of verapamil detectable by this method was 40 ng/mL of sample. The elimination half-life (β-phase) of this drug in rabbits was found to be 3.7 hours.

ISSN:0003-2719    

DOI:10.1080/00032718508069103

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A spectrophotometric determination is described for cephalosporins, offering adequate sensitivity and good precision. The procedure applies successfully to a wide variety of cephalosporins, also in pharmaceutical preparations: cephalothin, cefacetrile, cephapirin, cefotaxime, ceftizoxime, cephaloridine, cefazolin, cefamandole nafate, cephalexin, cefadroxil, cefoxitin and cefuroxime. The method employs a reaction with ammonium molybdate in sulphuric acid medium. The antibiotic is heated at 91.5°C for 15 min and the absorbance of the coloured product is measured at 670 nm against a reagent blank treated similarly. Beer's law is obeyed up to 125 to 150 μg of cephalosporin in the 5-ml final solution. The effect of reagent concentration and reaction conditions are discussed.

ISSN:0003-2719    

DOI:10.1080/00032718508069104

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Colourless silver-gelatin complex is quantitatively reduced by ascorbic acid to yellow silver sol in water within the pH range 7.5–10.0 at room temperature. The determination of 1–10μg/ml of ascorbic acid is possible at 415 nm in the presence of glycine, alanine, fructose, sucrose, citric, tartaric, oxalic, malic, succinic acids and also in the presence of various reducing agents. The molar absorptivity of ascorbic acid at the δmaxis found to be 21500 lit mol−1cm−1and the Sandell sensitivity of the sol is 8.18x10−3μg ascorbic acid cm−2for 0.001 absorbance. The relative standard deviation is ±0.22% and the confidence limit (20 determinations, 95%) being 8.806±0.0093%.

ISSN:0003-2719    

DOI:10.1080/00032718508069105

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

An antibody IgG-coated polystyrene ball was incubated with an antigen and then with affinity-purified Fab'-enzyme conjugate in the presence of normal IgG, F(ab')2, Fab' or Fab'-bovine serum albumin conjugate. After washing by incubation at 30[ddot]C for 10 min with shaking, the enzyme activity bound to the polystyrene ball was assayed. The non-specific binding of the Fab'-enzyme conjugate to the polystyrene ball considerably decreased in the presence of normal IgG and the other related proteins, while the specific binding decreased only slightly. As a result, the detection limit of hCG, human IgE and human α-fetoprotein was improved 3 to 10-fold.

ISSN:0003-2719    

DOI:10.1080/00032718508069106

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The influence in the amount of crosslinker (methylenebisacrylamide) on the mobility of peptides during polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate has been tested. A drastic change in the mobility, dependent on the ratio crosslinker: acrylamide used, was found for keratins and vimentin which could invert their mobility with respect to other polypeptides.

ISSN:0003-2719    

DOI:10.1080/00032718508069107

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A rapid method (less than 20 min/sample from sample preparation through final determination) is described for the determination and confirmation of the plant toxin, myristicin [1-allyl-3-methoxy-4,5-methylenedioxybenzene], in fresh, frozen, and canned carrots at levels ranging from 5 to 20 ug/g. Myristicin is extracted from carrot homogenates with hexane in the presence of sodium bisulfite. An aliquot of the crude extract is separated from interfering lipids and pigments using a commercially available silica gel cartridge. The purified extract is concentrated and then analyzed by gas chromatography on a nonpolar stationary phase (OV-101) using flame ionization detection. Suspected positive findings are confirmed using a second stationary phase of moderate polarity (OV-225). Recoveries of added myristicin to fresh and processed carrots at levels from 5 to 20 ug/g averaged 95.6% with a coefficient of variation of 4.8%. Six samples of fresh carrots collected from different growing areas exhibited levels of myristicin from 1.1 to 16.6 ug/g. The limit of detection of the method is approximately 0.5 ug/g.

ISSN:0003-2719    

DOI:10.1080/00032718508069108

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor