摘要:

An amperometric glucose biosensor based on a polymeric cobalt tetraaminophthalocyanine (p-CoTAPc) film coated glassy carbon (GC) electrode was developed. The monomer, Co(II)-4, 9, 16, 23-tetraaminophthalocyanine, was electropolymerized at a glassy carbon electrode for detecting hydrogen peroxide in the presence of oxygen by electrocatalytic oxidation. Glucose oxidase (GOD) was immobilized on the p-CoTAPc film coated glassy carbon electrode by cross-linking with glutaraldehyde for glucose assay and a layer of polyphenol (PPh) film was electropolymerised on the enzyme layer for guaranteeing the permselectivity. The biosensor retains its full activity for at least three months and responds rapidly to glucose with a detection limit of 8×10−6M and a linear concentration range of 1×10−5− 2×10−3M. The polyphenol film can not only prevent interferences from some electroactive species, e.g. ascorbic acid, uric acid and cysteine etc., but also increases the thermal stability of the biosensor. The electrode was successfully applied in clinical analysis of glucose in human blood plasma.

ISSN:0003-2719    

DOI:10.1080/00032719708006415

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A new method for flow injection analysis of norepinephrine bitartrate has been developed. It is based on ion association with anionic surfactant and piezoelectric detection. Sodium dodecyl phenylsulfate was used as the ion association reagent. The calibration curve was linear between 0.01 and 1.20 mg/ml. with a detection limit of 5 μg/ml, a relative standard deviation of 0.18% (10 replicates) and a sampling frequency of 120/h. The proposed method has been satisfactorily applied to the determination of norepinephrine bitartrate in pharmaceutical preparations.

ISSN:0003-2719    

DOI:10.1080/00032719708006416

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A simple, efficient and economic device for fluoride mass transference is presented in this study. Hexamethyldisiloxane (HMDS) is used to volatilize fluoride and, in addition to 0.05M NaOH, 0.3M citrate/phosphate/1 M KCl, pH 7.8 (buffer A) and 0.5 M citrate pH 5.5 (buffer B) are used as the trapping solution with the aim of an additional gain when concentration is a limiting condition in the use of the selective electrode. Using 0.05M NaOH, the fluoride mass transferred was in the range of 40 - 0.2 μg, and with buffer A the mass transferred was around 0.2 μg, with a total recovery in a few hours. The influence of interfering substances on fluoride volatilization was assessed. Fluoride was transferred from standard solutions in either the absence or presence of interfering substances (ethanol, propyleneglycol, glycerol, sorbitol, artificial saliva), and the respective recoveries were determined. Due to its simplicity and low cost several device units can be assembled allowing simultaneous analysis for rapid and accurate comparison of different samples. This device is useful for eliminating interfering substances, to concentrate samples as a function of the limit of method, and/or to attenuate gradative loss of the electrode sensitivity.

ISSN:0003-2719    

DOI:10.1080/00032719708006417

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A new probe for the determination of fructose and glucose has been assembled using a platinum electrode and three enzymes co-immobilized on its surface: fructose dehydrogenase, glucose dehydrogenase and diaphorase. The mechanism of this probe is very simple: when the probe is immersed in a solution containing fructose and glucose and an electrochemical mediator, the current signal is due to the fructose. Then, by adding NAD(P)+a current response due to the glucose present in solution is obtained.

ISSN:0003-2719    

DOI:10.1080/00032719708006418

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Interaction of the water-soluble platinum and palladium coproporphyrins with cationic carriers, DEAE-dextran and CTAB, was investigated in aqueous solution by optical spectroscopy including pH-dependences of the absorption and emission spectra. In addition, solid-state coatings of the complexes were prepared on solid supports and their phosphorescent properties were studied. Contrary to the pure dyes, in the dry and solid state, the complexes strongly phosphoresce in air, are weakly quenchable by air oxygen, but are sensitive to the water content in their environment. Their applicability to quenched-phosphorescence sensing was discussed and compared to that of the phosphorescent polymer film compositions and Langmuir-Blodgett coatings.

ISSN:0003-2719    

DOI:10.1080/00032719708006419

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Application of a partial least squares algorithm (PLS-1) is proposed in this work for simultaneous spectrophotometric determination of calcium and magnesium in human serum. Two chromogenic agents, Calmagite [1-(1-hydroxy-4-methyl-2-phenylazo)-2-naphtol-4-sulfonic acid] ando-Cresolphtalein [3′,3″-bis{[bis-(carboxymethyl)amino]methyl}-5′5″-dimethylphenolphtalein] were used, which form color complexes with the two elements studied. As expected, significant interferences were observed for the individual methods (Ca-o-Cresolphtalein and Mg-Calmagite) in the presence of the second metal. However, applying a full-spectrum chemometric method PLS-1, it was possible to eliminate these interferences in the calibration step and satisfactory prediction results were obtained for calcium and magnesium in real serum samples. The proposed procedure was validated using Refererence Serum (171760 Boehringer Mannheim, Germany). The analytical results obtained for human serum were compared with the results of AAS determination.

ISSN:0003-2719    

DOI:10.1080/00032719708006420

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Tetraiodo phenol sulfonphthalein (TIPSP) reacts with protein rapidly to form the dye-protein complex with an absorbance maximum at 617 nm. Water is used as the blank instead of the reagent blank because the reagents have no absorption at this wavelength; thus the operating steps are simplified. Under the experimental conditions (0.03 mM TIPSP, pH 2.63), the linear range of this assay is composed of three parts: 10.2–54.4μg·ml−1, 54.4–95.2 μg·ml−1and 95.2–136.0 μg·ml−1. Most amino acids, reducing reagents (e.g. ascorbic acid) and complexing reagents (e.g. EDTA) don't interfere with the assay. The interferences from detergents, salts and ethanol can be minimized by dilution. In detection of human serum albumin, this method gave results close to that of the bromocresol green assay.

ISSN:0003-2719    

DOI:10.1080/00032719708006421

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Capillary zone electrophoresis was employed for the analysis of cytochromecusing an end-column amperometric detector with a L-cysteine-modified gold microdisk array electrode. The optimum conditions of separation and detection are 0.04 mol/L KH2PO4- 0.06 mol/L Na2HPO4for the buffer solution, 8 kV for the separation voltage, 4 kV and 10 s for the injection voltage and the injection time, and −0.12 V vs. SCE for the detection potential. When the fused-silica capillary modified by ethylene glycol was used, the adsorption of cytochromecon the surface of the capillary wall could be overcome. The limit of detection is 3 × 10−5mol/L or 62 fmol (S/N = 2). The method was applied to determining cytochromecin pig heart.

ISSN:0003-2719    

DOI:10.1080/00032719708006422

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The voltammetric characteristics of adenine and adenosine at a copper electrode were investigated in different supporting electrolytes. It was found that citric acid had some activating effect at the copper electrode and the oxidation reaction of adenine and adenosine at the copper electrode could be observed in the solution, if PO43−and citric acid exist simultaneously. The oxidation reaction of adenine and adenosine could be applied to capillary zone electrophoresis with end column amperometric detection for their determination. The method was applied to the determination of adenine in yeast-RNA.

ISSN:0003-2719    

DOI:10.1080/00032719708006423

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Electrothermal atomic absorption spectrometry (ETAAS) of rhodium with a tungsten tube atomizer has been investigated under optimum conditions (atomization temperature; 2230 C, purge gas; Ar 480 ml min−1+ H220 ml min−1, and pyrolysis temperature; 590 C). The absolute characteristic mass (the mass of element giving 0.0044 abs.) of rhodium by the atomizer was 86.5 pg and the detection limit was 16.5 ng ml−1(3S/N). The interferences caused by large amounts of interferents were evaluated. Al, Ca, Cu, Fe, K, Mg, Na, Pb and Zn severely interfered in the AA signal of rhodium. Ammonium phosphate, ascorbic acid, palladium nitrate, copper nitrate, lanthanum nitrate, thiocyanate and thiourea, well known as matrix modifiers were tested to eliminate the severe interferences. However, by the addition of these compounds, the rhodium signal was not recovered. The standard addition method was adapted for the determination of rhodium in biological materials. The recovery of spiked-rhodium in biological materials was in the range of 97.4 to 107%.

ISSN:0003-2719    

DOI:10.1080/00032719708006424

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor