摘要:

The specific and accurate determination of selenium in human hair can be effected using catalytic polarography in a medium of Na2SO3- KNO3. Sample recovery ranges from 97% to 104%. The selection of experimental conditions and factors that affect the determination were studied in detail. The results show that the medium acidity doesn't have much influence on the measurement, so that the process of sample digestion is simplified. The buffer NH3- NH4C1 improves the stability of analyte and high reproducibility is obtained. The catalytic process and mechanism are also presented in this paper.

ISSN:0003-2719    

DOI:10.1080/00032718808055743

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

hIL-1αa and hIL-1β were demonstrated and measured in culture supernatants of peripheral blood monocytes and mononuclear cells by sensitive and specific enzyme immunoassays. Two components for both hIL-1α and hIL-1β were demonstrated by gel filtration of culture supernatants: one with the same molecular weight as recombinant hIL-1α or hIL-1β and the other with a molecular weight of about 30,000. The production of hIL-1α and hIL-1β increased 1.6 to 38-fold in the presence ofEscherichia coli (E. coli)lipopolysaccharide. Levels of hIL-1α and hIL-1β became almost plateau within 24 h in culture supernatants of monocytes but became maximal within 12–18 h and decreased afterwards in culture supernatants of mononuclear cells, suggesting that hIL-1α and hIL-1β were produced by monocytes and consumed or degraded by other cells. In addition, hIL-1α and hIL-1β were detected in sera from patients with various disorders but not in sera from healthy subjects.

ISSN:0003-2719    

DOI:10.1080/00032718808055744

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

L-DOPA (3,4-dihydroxy-L-phenylalanine) reduces the phosphotungstic acid reagent whereas tyrosine does not. We have modified the usual assay conditions to give a relatively stable blue color while avoiding the use of cyanide by lowering the pH.

ISSN:0003-2719    

DOI:10.1080/00032718808055745

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Stereoselective method for high-yield synthesis of 4-trifluoromethylumbelliferyl-β-D-galactopyrano-side - fluorigenic substrate for β-galactosidaseE. coli, as enzyme label for ELISA, has been developed.

ISSN:0003-2719    

DOI:10.1080/00032718808055746

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The adsorptive stripping voltammetric behaviour of the lectin, phytohemagglutinin, has been optimised with respect to accumulation time, accumulation potential, pulse amplitude, scan rate and drop size. Adsorptive stripping voltammetry has also been used to study the interaction of this protein with nannose, galactose and N-acetyl-D-galactosamine.

ISSN:0003-2719    

DOI:10.1080/00032718808055747

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The application of a pyruvate-sensing bienzyme electrode based on lactate dehydrogenase, lactate mono-oxygenase and an oxygen probe for pyruvate kinase (PK) determination in erythrocytes is described. PK can be measured in the range 0.12 – 1.85 μmol/(s1) with good reproducibility and good agreement with the conventional method. Coimmobilization of PK in the enzyme membrane leads to asensor for creatine kinase determination useful in the range 0.1 – 1.76 μmol/(s1).

ISSN:0003-2719    

DOI:10.1080/00032718808055748

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Biamperometric titration and differential pulse polarography (DPP) are described for the analysis of nomifensine maleate powder and commercial capsules (MeritalR-50 mg). The biamperometric method involved the titration in cold dil. HCl medium against 0.01 M - NaN02and electrometric detection of end point. The mean percent recoveries obtained were 100.0 ± 0.87 and 99.2 ± 0.95 for the authentic powder and capsules, respectively. The DPP method was performed by measuring the peak current, iP, obtained from the recorded differential polarogram under constant 50mV modulation amplitude. The peak current was measured at the peak potential of − 1.02 V on the dropping mercury electrode (DME) versus Ag/AgCl/KCl (sat.) reference electrode at pH 5.0 (acetate buffer). A linear relationship between peak current and concentration was demonstrated in the range 3 to 30μg ml−1. The mean percent recovery for the capsules was 103.1 ± 1.26.

ISSN:0003-2719    

DOI:10.1080/00032718808055749

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

A method based on the use of an ion-exchange column, post-column derivatization with 2,4-pentane-dione (acetylacetone), and photometric detection for the determination of low levels of formaldehyde in aqueous solution is described. The lower limit of detection is 5 μg/L (ppb) and response is linear up to at least 10 mg/L. Reproducibility at the 1 mg/L level is 0.6% RSD. Determination of formaldehyde concentration in several aldehyde systems is demonstrated.

ISSN:0003-2719    

DOI:10.1080/00032718808055750

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

An electrothermal atomization atomic absorption spectrometric (ET-AAS) method is developed for the direct determination of Ag,Be,Cd,Li and Pb in thorium nitrate solution. The method offers detection of sub-nanogram amounts of these analytes in 100 microgram thorium samples with a precision of around 10%. A number of spiked samples and pre-analysed Th02samples have been analysed to evaluate the performance of the analytical methods developed here.

ISSN:0003-2719    

DOI:10.1080/00032718808055751

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The color reaction systems between various metal ions and o-hydroxyhydroquinonephthalein(Qnph) as a xanthene dye, in the presence of various water soluble surfactants(cationic. anionic, non-ionic surfactants) alone or in combination, were systematically investigated at various pH areas. The coexistence of cationic and non-ionic surfactants, such as Zephiramine (Zp) and Brij 35, was most effective for the color reaction systems between Qnph and gallium(III), as a metal ion, at weakly acidic media. By using the color reaction between Qnph and gallium(III) in the coexistence of Zp and Brij 35, an improved and sensitive spectrophotometric determination of gallium(III) was proposed as method 1, and the calibration curve was rectilinear in the range of 0∼7.0 μg of gallium(III) in a final solution of 10ml at pH 6.4. The apparent molar absorptivity was 1.5 × 1051 mol−1cm−1at 560 nm, and the interference of foreign ions was decreased by ½∼ ¼-fold in comparison with other methods; method 3—in the presence of Zp alone at pH 6.4, method 2—in the presence of Tween or Brij 35 alone, without Zp, at pH 8. Thus, the use of Qnph as a xanthene dye and the combination of cationic and non-ionic surfactants, such as Zp and Brij 35(perhaps, on the mixed micellar media), was most effective and its color reaction was used for the separative assay of gallium(III).

ISSN:0003-2719    

DOI:10.1080/00032718808055752

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor