摘要:

A bacterial electrode for the determination of urea has been constructed by immobilizing theProteus mirabilison a carbon dioxide gas-sensor. the electrode gave a Nernstian behaviour between 7.0 × 10−4and 3.0 × 10−2M urea with a slope of 46 mV/decade in pH 6.80, 0.1M phosphate buffer at 30°C. the important interferences were L-asparagine, cytosine, inositol and phenol, and most inorganic salts reacted as the inhibitor. This electrode showed little change in the response and linear rane for 7 days, and could also be used in the linear range because the electrode had good reproducibility even after this. This device could be used as easily and exactly as a spectrophotometric method in clinical applications.

ISSN:0003-2719    

DOI:10.1080/00032718908051181

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

An L-tyrosine sensor consisting of immobilized L-tyrosine decarboxylase and an amperometric bacterial CO2sensor was developed, and evaluated. the optimum pH was 5.5 and the optimum temperature was between 32°C and 34°C. A linear calibration curve was obtained in L-tyrosine concentrations between 10 μM and 50 μM.

ISSN:0003-2719    

DOI:10.1080/00032718908051182

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The potential of the ammonia selective electrode was plotted versusiog [NH4C1] in solutions to which a tenfold excess (v/v) of 10 M NaOH was added. ‘Eisenman plots’ were obtained in the presence of ten different aliphatic amines. Corresponding potentiometric selectivity coefficients (PSC) were evaluated. These correlated as follows with the dissociation constants of ammonia (K') and of the relevant amine (K): log PSC = pK'a-pKa. Accordingly, deviations from correct ammonia electrode potentials increased with amine base strength. This effect can be compensated by adjusting the internal solution of the ammonia electrode to match the composition of the so-called ‘total basic volatile nitrogen’ in the conventional sample distillate.

ISSN:0003-2719    

DOI:10.1080/00032718908051183

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Carboxyl groups on a collagen membrane were activated with the aid of an acyl-azide reaction. the enzyme oxalate oxidase, prepared from barley seedlings, was subsequently immobilized on the activated collagen film. the specific activity and the Michaelis constant were 0.13 units/cm2and 0.1 M, respectively. Enzyme activities were determined as function of pH, ionic strength, and ambient chloride concentration, intercomparing the enzyme in aqueous solution with its immobilized counterpart. Oxalate was quantitated amperometrically via electrooxidation of the hydrogen peroxide by-product generated in the reaction between oxalic acid and O2. the detection limit of oxalate was 10−5, which yielded a current of 2 nanoampere.

ISSN:0003-2719    

DOI:10.1080/00032718908051184

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The chromatographic behaviour of 15 physiologically important organic acids has been studied on papers impregnated with hydrated stannic oxide. the mechanism of separation is discussed. Numerous bioanalytically important binary and ternary separations were achieved by using various aqeous, non-a queous and mixed solvent systems.

ISSN:0003-2719    

DOI:10.1080/00032718908051185

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Results on a direct determination of selenium in horse blood are presented. A 10 mg/L solution of nickel was added to the blood after the blood was treated with Triton X. This provides a means of direct determination of selenium in horse blood and cuts out the time consuming digestion step. the accuracy of the method was good and the precision of greater than 10 percent was considered acceptable.

ISSN:0003-2719    

DOI:10.1080/00032718908051186

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A flow injection system for the determination of D-glucose using on-line dialysis is described and its potential use for whole blood measurements is evaluated. Glucose is degraded enzymatically by means of glucose oxidase which is immobilized on controlled porosity glass and incorporated into a small PVC column reactor. the hydrogen peroxide generated by the glucose oxidase is determined by chemiluminescence with an alkaline reagent containing luminol and hexacyanoferrate (III). the detection limit was 0.1 mM glucose with a sampling frequency of 95 h-1 and a standard deviation of less than 1.5%. the enzyme reactor showed little change in activity over a 6 months period of operation. the use of an open tubular nylon coil, in which the glucose oxidase is immobilized to the wall, is also described.

ISSN:0003-2719    

DOI:10.1080/00032718908051187

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A new spectrophotometric method for the determination of piroxicam has been developed. the method depends on the reaction of piroxicaam with copper (II) and iron (III) in methanolic hydrochloric acid solution where piroxicam is found to form 1:1 complexes with both metal ions with maximum absorption at 372 nm and 527 nm. Average log. stability constants of 4.872 and 4.546 were obtained for piroxicam-copper (II) and piroxicam-iron (III) complexes, respectively.

ISSN:0003-2719    

DOI:10.1080/00032718908051188

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Thermodynamic dissociation constants of piperidine and piperazine compounds have been determined at 20°C by combining two experimental techniques. These compounds have chromophoric changes dependent upon the pH of the solution. Using spectrophotometric measurements and potentiometric titration data, all constants have been calculated. the values determined by means of both methods are in good agreement.

ISSN:0003-2719    

DOI:10.1080/00032718908051189

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

First (D1-) and second (D2-) derivative spectrophotometric methods have been proposed for the assay of 7 cephalosporins, each with its alkali-induced degradation product in combination. Solutions of these cephalosporins in McIlvaine's citric acid-phosphate buffer pH 7.0 were analyzed by measuring the 1st and 2nd derivative spectral response at certain wavelengths where the respective degradation products exhibit no contribution. the latter could be determined at the selected λ in the vicinity of negligible absorbance of the corresponding intact drug. Kinetic investigation of the alkaline degradation rate of cephalosporins revealed that the proposed methods were stability indicating. the different cephalosporin pharmaceutical preparations were assayed and gave results of equal accuracy (t-test)& reproducibility (F-test) with the corresponding official method of assay.

ISSN:0003-2719    

DOI:10.1080/00032718908051190

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor