摘要:

A GC-MS-SIM assay for PGE-M recently developed by us (Analyt. Biochem. 128:351–358, 1983) is based on the use of the diethyl ester of the analyte as the Internal standard (IS). Because the decay rate of this is and that of the underivatized metabolite cannot be assumed to be Identical, we determined the half-lives of both species so that data can be adjusted accordingly when the urine specimens are stored for a prolonged time. At -22°C the first-order rate constant of PGE-M decomposition and that of its diethyl ester are 3.120 × 10−3day−1(t1/2222 days) and 2.422 × 10−3day−1(t1/2286 days), respectively. Thus, if the storage time is less than 60 days data adjustment can be omitted, the consequent error being less than 4.3%.

ISSN:0003-2719    

DOI:10.1080/00032718508059854

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A chemiluminescence-delay technique has been developed for the assay of clinically important reductants. Under the experimental conditions described the time de lay before chemiluminescence is observed exhibits a linear dependence on substrate concentration up to ∼ 6 × 10−5M. The method, utilises the ferrihaem-catalysed oxidation of luminol by hydrogen peroxide as the light-emitting reaction. Specificity is conferred upon the assay by the use of the appropriate oxidoreductase enzymes. The technique has been applied in the estimation of ascorbic acid and uric acid in aqueous standards and biological samples.

ISSN:0003-2719    

DOI:10.1080/00032718508059855

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

L-ascorbic acid membrane electrodes based upon the use of four classes of biocatalysts immobilized at an oxygen electrode are evaluated and compared in terms of electrode properties and operating requirements. Isolated ascorbate oxydase enzyme in soluble form and in covalent binding matrices, peel of cucumber and living bacterial cells of Enterobacter agglomerans strain, respectively, are employed as biocatalytic layers. The physico-chemical factors, life times and interferences are discussed in details. The low stability of the soluble enzyme sensor does not allow its analytical utilization, but the immobilized enzyme, bacterial and tissue electrodes can be used, even in multivitamin pharmaceutical formulations. The common linear range of those three biosensors are of 4.10−6M to 7.10−4M with a precision and a reproducibility of ± 3%.

ISSN:0003-2719    

DOI:10.1080/00032718508059856

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Liquid-solid extraction of vitamin D3metabolites from human plasma using octadecylsilane bonded silica has been studied. Steroid-protein interactions were minimized by diluting the plasma (or serum) with two volumes of saline and passing the solution through the sorbent at 64°C. Highly purified secosteroid fractions were obtained by washing with aqueous methanol, drying the sorbentin situwith a stream of nitrogen for one minute and eluting with mixtures of hexane/chloroform. Recoveries of vitamin D3metabolites were essentially quantitative. Applications to the rapid analysis of 25-hydroxy- and 1α, 25-dihydroxy-vitamin D in plasma by high-performance liquid chromatography, gas chromatography-mass spectrometry or by a receptor protein assay are reported.

ISSN:0003-2719    

DOI:10.1080/00032718508059857

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Human growth hormone (hGH) was demonstrated in normal urine by a highly specific and sensitive sandwich enzyme immunoassay. The molecular weight of hGH in normal urine was shown to be 22,000 by gel filtration, and levels of urine hGH were 15–64 ng/1 or 50–83 ng/g of creatinine in normal subjects aged 1.2–5.9 yr.

ISSN:0003-2719    

DOI:10.1080/00032718508059858

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

It is shown that porcine kidney tissue can serve as an effective biocatalyst in the construction of a potentiometric membrane electrode with response and selectivity for glucosamine-6-phosphate. Electrodes using this tissue material in conjunction with NH3gas sensing probes yield good response to glucosamine-6-phosphate in the 5 × 10−5M to 10−3M range and retain activity for at least 3 weeks. The resulting sensors have good selectivity when operated at an optimum pH of 9.25.

ISSN:0003-2719    

DOI:10.1080/00032718508059859

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The effect of photolysis upon the fluorescence of chloroquine is studied and found to give only a marginal (∼16%) increase in signal. On the other hand, a pH of 7–11 gives a constant maximum fluorescence signal which is ≈4X greater than at a pH of 3–5. Chloroquine in a flowing solution is passed through a flow cell in a fluorimeter. A detection limit of 0.25 ng/ml is obtained and linearity to greater than 60 ng/ml is obtained. Chloroquine added in vitro to human blood serum is determined with recoveries greater than 94%.

ISSN:0003-2719    

DOI:10.1080/00032718508059860

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A high performance liquid chromatographic method for the determination of tropatepine in human plasma and urines is described here. After addition of an internal standard (2 chloro-11-(4-methyl piprazine 1-yl) dibenzo (b-f)(1–4) thiazepine) to the biological fluid and extraction at pH 12.0 in hexane, the analysis was performed on a reversed phase column (C18 microBondapak) with UV detection at 231 nm. The compound was eluted by a perchlorate buffer-acetonitrile mixture with a flow rate of 1.7 ml/min. The detection limit was about 25 ng/ml; reproducibility was around 7.5% for plasma concentrations below 50 ng/ml. Mass spectrometry by direct insertion probe had validated the chromatographic results. The method was successfully applied to plasma specimen collected from a healthy human volunteer following a single intravenous administration of 20 mg of tropatepine.

ISSN:0003-2719    

DOI:10.1080/00032718508059861

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A method has been developed to estimate primaquine in whole blood and urine by sensitive and selective high-performance liquid chromatography. Using the linear chain analogue of primaquine as the internal standard, a single-step extraction, normal-phase silica column with a basic mobile phase, levels down to 1 ng/ml of primaquine could be measured with good precision. Other anti-malarials like amodiaquine and pyrimethamine did not interfere in the assay. The major carboxylic acid metabolite of primaquine did not elute under the normal-phase chromatographic conditions. The method is suitable for use in clinical pharmacokinetic studies with primaquine.

ISSN:0003-2719    

DOI:10.1080/00032718508059862

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

This paper reports a simple, accurate, reproducible, stability-indicating procedure which may be used to quantitatively determine methenamine base, methenamine mandelate or methenamine hippurate in tablet dosage forms. The procedure initially involves the separation of methenamine from the dosage form and from formaldehyde, the decomposition product, by a cartridge ion-pair extraction process. The methenamine may then be assayed by a number of methods. In this paper the methenamine was hydrolyzed to formaldehyde and the formaldehyde determined by the Nash procedure. The method compares favorably with the USP XXI procedure for methenamine tablets. Advantages of the procedure include the ability to use a single method for the base and salt forms of the drug and the potential application to stability and quality control studies of methenamine dosage forms.

ISSN:0003-2719    

DOI:10.1080/00032718508059863

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor