摘要:

The selectivity and sensitivity of glucose measurements at carbon-paste based amperometric biosensors are greatly enhanced through the use of ruthenium-dispersed graphite particles. The improved performance is attributed to the substantial lowering of the overvoltage for the reduction of the hydrogen peroxide product. Hence, cathodic measurements of glucose can be caried out at an optimal potential range (-0.15 to +0.20 V). Contributions from easily oxidizable substances (e.g. acetaminophen, ascorbic and uric acids) are eliminated, without the need for mediators or membrane barriers. The electrocatalytic action of the ruthenium sites results also in a substantially improved sensitivity. A fast flow injection operation is illustrated.

ISSN:0003-2719    

DOI:10.1080/00032719308017433

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Immunohistochemical localization offers a fast and reliable method of obtaining information about the distribution of bound pesticide residues in plants. In the present study aquatic macrophytes (Elodea canadensis, Myriophyllum spicatum) were grown in laboratory model ecosystems spiked with 50 μg/l atrazine. To label cryosections, monoclonal antibodies from cell culture supernatants and ascites fluid with differing specificities for s-triazines were used in combination with the fluorescent dye Phycoerythrin and biotin-streptavidin amplification. The best results were observed with antibodies gained from mice immunized with an ametryn sulfoxide-BSA conjugate, regardless of the method employed for antibody production. The consequences with respect to herbicide metabolism and binding are discussed.

ISSN:0003-2719    

DOI:10.1080/00032719308017434

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

An optical flow-through biosensor based on the transient retention of p-nitrophenol on an ion-exchange support packed in the flow cell is presented. The approach was applied to the determination of the activity of some enzymes which catalyze the conversion of p-nitrophenyl-derivatives into p-nitrophenol. The method was first developed for determination of p-nitrophenol yielding a linear range between 0.1–5 μg/mL (r2= 0.9922, r.s.d.% less than 2.5), then, it was also applied to the determination of β-D-glucuronidase activity in serum, with a linear range between 0.1–20 U/L (r2= 0.9976, r.s.d.% less than 3.0), and a sampling frequency of 20 h−1. The application of the method to the determination of the enzyme activity in serum samples provided results consistent with those obtained by a conventional method and recoveries within 95–104%.

ISSN:0003-2719    

DOI:10.1080/00032719308017435

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Reverse - phase High Pressure Liquid Chromatography with a gradient elution on a LiChrocart 250-4 LiChrospher 100 RP-18 column has been used to separate and quantify 7 α-hydroxyandrostenedione (7α-OHA), 6β-hydroxyandrostenedione (6β- OHA), 16α-hydroxyandrostenedione (16α - OHA), 2 β - hydroxyandrostenedione (2 β - OHA), testosterone (T) and androstenedione (A). These steroids are the major products of androstenedione hydroxylation by adult rat liver microsomes. Separation was achieved in 30 minutes by using a linear gradient of acetonitrile (CH3CN) and water in increasing amounts from 30% to 60% of the first solvent (CH3CN).

ISSN:0003-2719    

DOI:10.1080/00032719308017436

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The therapeutical action of diuretics has been attributed to their hydrophobic character, among other properties. Therapeutical and physiological classifications of diuretics are correlated. The site of action of high efficacay diuretics is the loop of Henle, that of intermediate efficacy diuretics is the distal tubule and that of low efficacy diuretics is the proximal and distal tubules, and the collecting duct. Partition coefficients between water and micelles offer a scale for hydrophobicity, which leads to a further correlation between retention in Micellar Liquid Chromatography (MLC), with a sodium dodecyl sulphate mobile phase and an ODS-C18column, and the sites of action within the nephron. The site of action of those diuretics showing the lower retention in MLC is the proximal tubule (acetazolamide) and the loop of Henle (loop diuretics), for those diuretics with an intermediate retention is the distal tubule (thiazides), and for those with a long retention is the collecting duct (potassium sparing diuretics).

ISSN:0003-2719    

DOI:10.1080/00032719308017437

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A sequential spectrophotometric method for the simultaneous determination of paraquat and diquat in plasma using second-derivative spectroscopy after ion-pair liquid-liquid extraction was developed. The paraquat and diquat in the last extract are reduced with alkaline sodium dithionite to coloured complexes whose absorption peaks appear at a different wavelength. The two herbicides can thus be determined sequentially over the wavelength ranges 454.3—446.4 nm (diquat) and 460—396 nm (paraquat), respectively.

ISSN:0003-2719    

DOI:10.1080/00032719308017438

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The determination of rifampin in the presence of its main degradation products, 3-formyl rifampin and rifampin quinone using two spectrophotometric methods is described. Both Glenn's method and first derivative spectrophotometry were successfully adopted. No preliminary separation steps were required in either cases. Both methods gave accurate and reproducible results for the determination of the drug in dosage forms. The percentage recoveries ranged from 99.33% ±0.63 to 100.2% ± 0.44. The proposed methods are more simple, rapid than other existing methods and can be readily adopted in control laboratory.

ISSN:0003-2719    

DOI:10.1080/00032719308017439

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

“Zero-crossing” derivative spectrophotometry has been used for determining binary mixtures of penicillin G and procaine penicillin G.

ISSN:0003-2719    

DOI:10.1080/00032719308017440

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Ranitidine hydrochloride in tablets (T) and injections (I) was determined by ultraviolet spectrophotometry (UVS) at 313 nm and visible spectrophotometry (VISS) at 615 nm, after reaction with 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH) and ferric chloride. For UVS, Beer's law was obeyed in the range 5.0 – 18.0 μg/mL. The coefficients of variation (CV) for the samples T were 0.36% and 0.71% and for the samples I were 0.51% and 0.24%. The recovery average (RA) was 99.88%. For UVS, Beer's law was observed in the range 1.44 – 5.76 μg/mL. The CV for T were 0.72% and 0.59%, and for I were 0.53% and 0.61%. The RA was 99.39%. The precision and accuracy of the two methods were compared.

ISSN:0003-2719    

DOI:10.1080/00032719308017441

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A differential pulse polarographic method for the identification and quantitative determination of enoxacin is described. The method is based on the electrochemical reduction of the drug at the dropping mercury electrode. It gives a well-developed polarographic response with a half-wave potential of -990 mV vs. SCE in 0.1 M HCl. The electroactive specie exhibits a diffusion-controlled polarographic wave and its limiting current shows a linear dependence with the enoxacin concentration in the range between 5.10−4mM and 1 mM. This characteristic is applied for determination of enoxacin in commercial tablets. The recovery study shows a good accuracy and precision for the developed assay (average of 101.1% and standard deviation of 1.99). Furthermore, a comparative UV spectrophotometric assay also is developed.

ISSN:0003-2719    

DOI:10.1080/00032719308017442

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor