摘要:

Nereistoxin blocks nicotinic cholinergic transmission, but the exact mechanism by which this dithiolane blocks nicotinic acetylcholine receptors is not clear. One possibility is that nereistoxin is reducedin vivoand the resulting product, dihydronereistoxin, reduces a disulfide bond in the region of the receptor where acetylcholine binds. Other possibilities include that nereistoxin oxalate as supplied is not pure and contains dihydronereistoxin, or that nereistoxin acts as a simple competitive antagonist. We report here a method for simultaneous detection of both nereistoxin and dihydronereistoxin using π reversed-phase, ion-pair high-performance liquid chromatography with electrochemical detection. The standard curve for nereistoxin is linear to 400 pmol, and the detection limit is 10 pmol. The working electrode response is stable for up to 60 injections. Reduction of nereistoxin to dihydronereistoxin by NaBH4was 92% complete under the conditions reported here, but reoxidation occurs slowly upon standing at room temperature. No dihydronereistoxin was detected in commercial samples of nereistoxin oxalate.

ISSN:0003-2719    

DOI:10.1080/00032719308019886

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Four systems used for chemiluminescence determination of horseradish peroxidase[luminol-H2O2(NaOH), pyrogallol-H2O2(pH 6.5), luminol-H2O2-para-iodophenol (pH 8.5) and luminol-H2O2-para-hydroxylbiphenyl (pH 8.5)] were studied. The experimental conditions were optimized and linear dynamic ranges and limits of detection determined. The HRP conjugates with different antibodies were also determined, on the basis of which methods for determination of insulin, gentamycin and Salmonella anatis by chemiluminescent immunoassay were established.

ISSN:0003-2719    

DOI:10.1080/00032719308019887

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A new siloxane polymer containing covalently attached Meldola Blue has been synthesized and shown to mediate the oxidation of the reduced nicotinamide adenine dinucleotide cofactor (NADH). Cyclic voltammetry and stationary potential experiments demonstrate that spectrographic graphite electrodes coated with this polymer can electrocatalytically regenerate NAD+at a substantially lower overvoltage (e.g., 0 mV vs. SCE) than can unmodified electrodes. These polymer-modified electrodes should be useful as transducers in dehydrogenase-based biosensors.

ISSN:0003-2719    

DOI:10.1080/00032719308019888

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A third-derivative spectrophotometric method for measuring the carboxyhemoglobin (HbCO) percent content and the amount of hemoglobin not bound to the toxic gas and hence available for oxygen transport (functional Hb) is proposed. The method is quite straightforward, rapid and inexpensive and can be used to diagnose CO intoxications with a high precision as regards the severity of the clinical picture involved.

ISSN:0003-2719    

DOI:10.1080/00032719308019889

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The equilibria existing in Co(II), Ni(II), Cu(II) and Pb(II) systems with trimipramine were established by direct current polarography. The study showed that polarographically inactive trimipramine may be polarographically analyzed in the presence of Co (II), Ni (II), Cu (II), and Pb(II) ions. The results allow the calculation of the stability constants and the electrochemical behavior of the formed complexes to be discussed, 1:1 (metal:ligand) complexes were detected.

ISSN:0003-2719    

DOI:10.1080/00032719308019890

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Three simple and sensitive spectrophotometric methods for the determination of aminoglutethimide are described. The first method is based on the diazotization of the drug and the reaction product is quantified spectrophotometrically at 273 nm. The second and third methods involve coupling of the diazotized salt of the drug with either ethyl acetoacetate (EAA) in alkaline medium or N-(1-naphthyl)ethylenediamine hydrochloride (NED) in acid medium, to give colored reaction products measurable at 368 nm and 558 nm, respectively. The optimization of different experimental conditions is described. The proposed methods were applied successfully to the determination of amino-glutethimide in tablets with good accuracy and precision. The reliability of the developed methods were established by comparing the obtained results with those given by the official United States Pharmacopeial XXII methods.

ISSN:0003-2719    

DOI:10.1080/00032719308019891

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A HPLC method has been developed to determine the concentrations of SAZ-VII-23 (3-benzoyl-7-isopropyl-3,7-diazabicyclo[3.3.1]nonane HClO4), a novel antiarrhythmic agent, in dog plasma and urine. Plasma treated with acetonitrile and alkalinized urine were extracted with chloroform- propanol (9:1). An aliquot was injected on to HPLC system using a C6reversed-phase column and acetonitrile-methanol-37.5 mM phosphate buffer, pH 6.8 (28.5:28.5:43 v/v) containing 4.0 mM triethylamine as mobile phase. Detection wavelength was 255 nm. The linear range were 0.04–8 μg/ml, and the lower limit of quantitation was 0.04 μg/ml in plasma and urine, respectively. The method was applied to determine plasma and urine concentrations and preliminary pharmacokinetic profiles of SAZ-VII-23 in a dog.

ISSN:0003-2719    

DOI:10.1080/00032719308019892

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A simple, direct and sensitive spectrophotometric method for the determination of the intact N-desmethyldiazepam in the presence of its degradation products, 2-amino-5-chlorobenzophenone and glycine, is developed. The proposed procedure is based on direct measurement of the absorbance of its acidified methanolic solution at 361 nm. The procedure determines 8–56 mcg ml−1of N-desmethyldiazepam with an accuracy of 100.2 ± 0.51%. The proposed procedure retains its accuracy in presence of up to 80% of the different degradation products. The procedure is applied successfully for the determination of N-desmethyldiazepam in bulk powder, tablets and drops.

ISSN:0003-2719    

DOI:10.1080/00032719308019893

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A procedure is described for the assay of phenylpropanolamine hydrochloride & isopropamide by HPLC using CROWNPAK column and detection at 200 nm. The system was aqueous perchloric acid as mobile phase containing 5 % methanol. Linearity studies were carried out using peak height measurements. There was > 99 % recovery and coefficient of variation was < 2% for formulation. The procedure was rapid, accurate, precise and specific for the assay of phenylpropanolamine HCl in presence of isopropamide.

ISSN:0003-2719    

DOI:10.1080/00032719308019894

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A reverse phase HPLC procedure is described for the determination of chloramphenicol and its hydrolytic product, 2-amino-1-(4-nitrophenyl)-propane-1,3-diol. The method was validated for reproducibility, linearity and recovery for both components. It was successfully applied to monitor post-marketing stability of ten batches of chloramphenicol ophthalmic solutions stored at room temperature. As compared to the BP method using solvent extraction and UV measurements, for the determination of chloramphenicol and its hydrolytic product in chloramphenicol eye drops, the suggested procedure was found to be relatively more accurate, precise and less time-consuming.

ISSN:0003-2719    

DOI:10.1080/00032719308019895

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor