摘要:

A glucose electrode was constructed by adsorbing glucose oxidase (GOD) on a modified electrode for H2O2oxidation, consisting of Pd/Au sputtered on graphite. Maximally, 0.8 U cm−2of GOD could be adsorbed. The electrode was used in a f.i.a. manifold for determination of glucose. Linear calibration curves were obtained in the concentration range 3. 10−64. 10−3mol L−1glucose. The applied potentials for glucose determination were + 300 mV vs. Ag/AgCl at pH 8.0, + 350 mV at pH 7.0, + 400 mV at pH 6.0 and + 500 mV at pH 5.0. The activity vs. pH profile of adsorbed GOD was broad having an optimum between pH 5 and 6. The apparent kinetic parameters for adsorbed GOD, KMappand imax, were found to be 50 mM and 160 uA at optimal pH.

ISSN:0003-2719    

DOI:10.1080/00032718708062934

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A new type of acetylcholine sensor was made with an Ion Sensitive Field Effect Transistor (ISFET) and acetylcholine receptor. The acetylcholine receptor was fixed on a polyvinylbutyral membrane which covered the ISFET gate. When acetylcholine was injected into this system, the differential gate output voltage gradually Shifted to the positive side and reached a constant value. This response was due to the positive charge of acetylcholine. A linear relationship was obtained between the initial rate of the differential gate output voltage change and the logarithmic value of the acetylcholine concentration. Acetylcholine was fixed in the range 0.1-10μM. When the acetylcholine receptor was immobilized with the lipid membrane, the response was amplified with both the positive charge of acetylcholine and sodium ion flux through the acetylcholine receptor's channel. Therefore, the difference in the differential voltage between the acetylcholine receptor-ISFET systems with and without the lipid membrane was caused by sodium ion flux through the acetylcholine receptor's channel.

ISSN:0003-2719    

DOI:10.1080/00032718708062935

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A highly sensitive reverse-phase high-performance liquid chromatography assay utilizing fluorescence activation has been developed for the quantitative analysis of the anti-estrogenic compound toremifene and its major metabolites, 4-hydroxy-toremifene and N-desmethyl-toremifene. Plasma samples containing various quantities of toremifene and its metabolites were spiked with an internal standard (nafoxidine), extracted with 2% n-butanol in hexane, and irradiated with high intensity ultraviolet light (254 nm). Aliquots of the extracted plasma components were then injected onto a C-18 reversed phase column and eluted isocratically with a mobile phase of water and triethylamine in methanol. Fluorescence of toremifene, its metabolites, and internal standard was measured at an excitation wavelength of 266 nm. -The sensitivity of this assay was 8.0, 15.0 and 5.0 ng/mL for toremifene, N-desmethyl-toremifene and 4-hydroxy-toremifene, respectively. Linearity was achieved for the concentration range of 25 to 400 ng/mL for all the compounds, with correlation coefficients of greater than 0.994. The assay presented is highly specific, very sensitive and demonstrates reproducible linearity throughout a wide range of clinically relevant plasma toremifene concentrations.

ISSN:0003-2719    

DOI:10.1080/00032718708062936

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The resolving power of high pressure liquid chromatography has been combined with the sensitivity of electrochemical oxidation to develop a method for determination of codeine and its metabolites, morphine and norcodeine, in plasma. Plasma samples containing Internal Standard (Dihydromorphinone) are extracted at pH 8.9 into a 2/98 v/v/ Butanol/methyl tertiary butyl ether organic solvent system and back extracted into 25 mM phosphate buffer pH 2.8. The optimal recovery is greater than 90% for codeine and 70% for morphine and norcodeine. Reverse phase chromatography (5 micrometer phenyl column) with detection by electrochemical oxidation at + 1.2 V vs. Ag/AgCl is utilized. The method is sensitive, specific and precise. This method is used to establish a concentration - time profile for plasma codeine and morphine from a human volunteer after a 60 mg oral dose of codeine phosphate. No measurable concentration of norcodeine was found in the plasma.

ISSN:0003-2719    

DOI:10.1080/00032718708062937

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The spectrophotometric evaluation of acidity constants of biacetylmonoxime nicotinylhydrazone is reported in this paper.

ISSN:0003-2719    

DOI:10.1080/00032718708062938

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

To determine mercury in geological materials, samples are digested with nitric acid and sodium dichromate in a closed teflon vessel. After bringing to a constant weight, the digest is mixed with air and a sodium chloride-hydroxylamine hydrochloride-sulfuric acid solution and then Hg(II) is reduced to Hg with stannous chloride in a continuous flow manifold. The mercury vapor is then separated and measured using cold vapor atomic absorption spectrophotometry (CV-AAS). For a 100 mg sample the limit of detection is 20 parts per billion (ppb) Hg in sample. To obtain a 1% absorption signal, the described method requires 0.21 ppb Hg solution (equal to 16 ppb in sample). Precision is acceptable at less than 1.2% RSD for a 10 ppb Hg aqueous standard. Accuracy is demonstrated by the results of the analysis of standard reference materials. Several elements do interfere but the effect is minimal because either the digestion procedure does not dissolve them (e.g., Au or Pt) or the; are normally of low abundance (e.g., Se or Te).

ISSN:0003-2719    

DOI:10.1080/00032718708062939

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

This paper recommends a simple and convenient procedure for the determination of cerium(III) on MnO2without separation of Mn. Several reducing agents and optimum conditions of determination were studied.

ISSN:0003-2719    

DOI:10.1080/00032718708062940

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A chemiluminescence - high performance liquid chromatography (CL-HPLC) system was developed for the hydroperoxide-specific detection of phosphatidylcholine hydroperoxide. In this system, chemiluminescence detector was equipped with normal phase HPLC. Luminol-cytochrome c solution was used as the hydroperoxide-specific luminescent reagent. A detection limit of 7 nmol hydroperoxide-O2of phosphatidylcholine hydroperoxide could be achieved.

ISSN:0003-2719    

DOI:10.1080/00032718708062941

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

An ion-selective electrode based on ionomycin methyl ester, a derivative of the naturally occurring carboxylic polyether antibiotic ionomycin, is described which exhibits high Li+selectivity. The selectivity coefficients of the electrode based on ionomycin methyl ester, log KpotLiNaand log KpotLiKare -1.3 and -1.9, respectively.

ISSN:0003-2719    

DOI:10.1080/00032718708062942

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Bis(2ethylexyl) sodium sulfosuccinate (AOT) can be determined using Adsorptive Stripping Differential Pulse Tensammetry (ASDP) in concentration range 5 10−7− 5 10−6M. Higher concentrations can be determined by direct Differential Pulse Polarography.

ISSN:0003-2719    

DOI:10.1080/00032718708062943

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor