摘要:

The construction of potentiometric, enantioselective membrane electrodes for several angiotensin-converting enzyme inhibitors as well as the mechanism of potential development and enantioselectivity are described.

ISSN:0003-2719    

DOI:10.1080/00032719908542844

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A method has been developed for discrete analysis of urinary oxalate employing alkylamine glass bound oxalate oxidase partially purified from mature leaves of Amaranthus spinosus. In the method H2O2is generated from urinary oxalate by immobilized oxalate oxidase, which is measured by a colour reagent containing 4-aminophenazone, phenol and horseradish peroxidase in phosphate buffer, pH 7.0. The chromogen formed is read at 520nm. The minimum detection limit of the method is 0.9mg/L. The analytical recovery of added oxalate in urine was 98.0±2.7% (mean±SD). Within batch and between batch CV's were less than 4% and 3%, respectively, for urinary oxalate determination. The mean value of urinary oxalate measured by the present method is comparable to that obtained by the Sigma kit method (r=0.98).

ISSN:0003-2719    

DOI:10.1080/00032719908542845

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A capillary optode for determination of mercury(II) in aqueous solution has been developed. The sensors are composed of the capillary glass tubes with a chemically sensitive coating on the inner surface, consisting of a 4-(2-thiazolylazo) resorcinol (TAR) and Nafion® composite thin film. When a sample solution is passed through a capillary tube, the mercury(II) ions forms complexes with the immobilised TAR resulting in a change of the colour of the inner surface of the capillary which, in turn, can be monitored spectrophotometrically. The characteristics of these sensors including effect of flow-rate and pH, reproducibility, sensitivity, linear range, life time and selectivity are discussed.

ISSN:0003-2719    

DOI:10.1080/00032719908542846

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Triphenyllead chloride was found to act as an ionophore for iodide. An electrode constructed using this ionophore and tris(2-ethylhexyl) phosphate as a membrane solvent in a poly(vinyl chloride) membrane matrix exhibited a near-Nernstian response to iodide in the concentration range 1x10−5-1x10−2M with a slope of-56 mV per concentration decade. The lower limit of detection was around 3 μM. The electrode displayed the following selectivity sequence: Γ > salicylate > SCN−∼ Br−> Cl−> ClO4−> CH3COO−> NO3−> SO42−∼ HPO42−> HCO3−, which largely deviates from the Hofmeister sequence and also is not in accordance with the selectivity sequence of an electrode based on triphenyltin chloride. The pH dependence of the electrode response was not significant in the pH range 2-7. Diphenyllead dichloride also exhibited a similar selectivity sequence as triphenyllead chloride, but sensitivity to iodide was much lower than for triphenyllead chloride.

ISSN:0003-2719    

DOI:10.1080/00032719908542847

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A mixture of 1,4-butanediyl diacrylate (BDDA) as cross-linker, α-methylacrylic acid (MAA) as functional monomer, ethyl 2,4,6-trimethybenzolphenylphosphinate as photoinitiator, and L-phenylalanine as imprinted molecule when exposed to a UV-laser beam produces a series of polymers. By high performance liquid chromatography, molecularly imprinted polymers exhibited good entantiomeric recognition properties.

ISSN:0003-2719    

DOI:10.1080/00032719908542848

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A Cu(II)-diethyldithiocarbamate modified carbon paste electrode was found to be highly selective for cysteine accumulation. Of the simple amino acids, only histidine interfered at 10 times the concentration of cysteine. Thiourea and thiocyanate ion interfered only when their concentrations were 30 times and 10 times greater than that of cysteine. The detection limit using differential pulse anodic stripping was 2.00 x 10−6mol 1−1cysteine and the determination of 5.00 x 10−5mol 1−1cysteine gave a precision of 3.95% (r.s.d., n = 8).

ISSN:0003-2719    

DOI:10.1080/00032719908542849

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A simple system for enzymatic flow-injection analysis of metabolites is described, which is based on the phosphorescence lifetime based detection of molecular oxygen using phase-modulation techniques and a simple instrument - phosphorescence phase detector equipped with a fibre-optic probe. The phase detector is connected to the oxygen sensor membrane and allows real-time continuous monitoring of the phosphorescence phase shift. This parameter is related to the phosphorescence lifetime of the oxygen probe, therefore giving a measure of the dissolved oxygen concentration, and its changes as a result of the enzymatic oxidative reaction with the substrate. The sensor membrane is positioned in a compact integrated flow-through cell and exposed to the flow stream.

ISSN:0003-2719    

DOI:10.1080/00032719908542850

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Variations of the cyclic voltammetric behavior of pharmorubicin in an aqueous medium upon addition of DNA were studied and utilized for the determination of DNA. It was observed that the redox waves of pharmorubicin after binding to the large and slowly diffusing DNA almost disappeared. The anodic peak currents of pharmorubicin, when the concentrations were fixed at 2.0 x 10−5and 2.0 x 10−4mol/L, decreased linearly correlated to the concentration of DNA added in the range of 0 - 30.7 and 0 - 260.3 μg/ml, with the detection limits of 1.2 and 20.8 μg/ml, respectively. The proposed method exhibited good recovery and reproducibility for the determination of DNA. Furthermore, the binding constant and binding site size of the pharmorubicin-DNA interaction were also calculated.

ISSN:0003-2719    

DOI:10.1080/00032719908542851

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The determination of amoxycillin using a flow-injection method with spectrophotometric detection is described. The method is based on the measurement of the intrinsic absorbance of amoxycillin fixed on Sephadex QAE A-25 resin. The determination of amoxycillin, using optimized variables, was carried out for three different sample volumes (300, 600 and 1200 μl), giving linear calibration graphs over the ranges 2-50, 1-25 and 0.5-15 μg ml−1, respectively. The relative standard deviations were ≤ 1%. The proposed method allows a very sensitive, rapid, and simple determination of amoxycillin in the presence of other penicillins, antibiotics, additives and excipients, without performing a prior separation or derivatization. A noticeable increase in sensitivity and lower detection limits can be easily achieved by increasing the sample volume injected. The method was successfully applied for the determination of amoxycillin in pharmaceutical formulations.

ISSN:0003-2719    

DOI:10.1080/00032719908542852

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A novel algorithm of the wavelet packets transform, which is more suitable than the multiresolution signal decomposition (MRSD) algorithm to process the practical signals in analytical instrumental analysis, was proposed. There is no limitation of data length for the algorithm like the MRSD algorithm and, sometimes, no need to perform the inverse transform in practical uses by the algorithm. Two methods for de-noising were proposed based on the algorithm, and application of the methods to de-noising of noisy chromatograms was investigated. The results showed that the efficiency of the proposed methods is higher than that of the conventional thresholding methods.

ISSN:0003-2719    

DOI:10.1080/00032719908542853

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor