摘要:

A new method combining flow injection methodology with quartz crystal microbalance (QCM) detection is proposed for inorganic mercury analysis. A modified simplex method is used in order to maximise the observed analytical signals (crystal frequency decrease). Six parameters were optimised: the concentration of the acidic carrier solution, the lengths of the sample loop and mixing coil, and the flow rates of the sample carrier, the reductant stream (SnCl2), and the carrier of the mercury vapour (N2). An increase of 18% in the signal of the centroid of the calibration line was achieved, as well as an increase in the sensitivity from 290 Hz μg−to 313 Hz μg−. Following the proposed procedure, detection limits of 47 μg L−of inorganic mercury were found for sample volumes of 0.5 mL.

ISSN:0003-2719    

DOI:10.1080/00032719908543000

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A novel fiber-optic DNA biosensor based on chemiluminescence is proposed. DNA probes were covalently immobilized onto the distal end of the optical fiber bundle. Hybridization of HRP (horseradish peroxidase)-labeled complementary nucleotides to the immobilized probes was detected by enhanced chemiluminescence. The detection limit (S/N=3) is 0.1 ppm. The approach is shown to be specific, sensitive and capable of diagnostic applications.

ISSN:0003-2719    

DOI:10.1080/00032719908543001

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Thiocyanate selective electrodes were prepared by incorporating cobalt and manganese phthalocyanines into plasticized ploy(vinyl chloride) membranes which were directly coated on the surface of graphite electrodes. A calibration plot with Nernstian slope for thiocyanate was observed over a linear range of five decades of concentration (1x10−6-1x10−M). The electrode has a fast response time, very low detection limit (5x10−7M thiocyanate), is easy to prepare, and could be used for over a month. The proposed sensor revealed good selectivity for thiocyanate over several anions and could be used over a wide pH range. Applications of the electrode to the potentiometric titration of silver ion with thiocyanate and determination of thiocyanate in urine samples are reported.

ISSN:0003-2719    

DOI:10.1080/00032719908543002

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A simple, rapid, convenient and highly sensitive flow injection procedure with chemiluminescence detection has been developed for the determination of rutin based on its inhibition of the chemiluminescence from the luminol-potassium hexacyanoferrate(111) system. The linear range is 2x10−8– 8x10−6g/mL and the detection limit is 6.7x10−9g/mL. The method has been successfully applied to determine rutin insophora japonica L.(traditional Chinese medicine).

ISSN:0003-2719    

DOI:10.1080/00032719908543003

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The high-performance liquid chromatographic behavior of some bases and nucleosides was studied on a new reversed-phase stationary phase, alkylphosphonate-modified magnesia-zirconia. The effect of mobile phase variable such as methanol content, ionic strength and pH on their behavior was investigated. It was found that the retention behavior of the bases and nucleosides on the new stationary phase is similar to that on ODS stationary phase. The retention mechanism on the new stationary phase was also discussed. The separation of some bases and nucleosides was accomplished on the new stationary phase.

ISSN:0003-2719    

DOI:10.1080/00032719908543004

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A new method for mutagenicity testing of carcinogens is proposed in this paper. Mutagenic activity is examined through monitoring of the growth situation ofSalmonella typhimuriumTA98 strain with a series piezoelectric quartz crystal (SPQC) sensor. This method needs no immobilization and preincubation of microorganism, and is simple and rapid. It can be applied to detect mutagen directly. When it was used to study the mutagenicity of dimethyl sulfate, the test time was 4 h at 37°C. There was a good linear relationship between frequency shift and the dose of mutagen in the range 2.5-20 μg/mL and the regression equation was ∠F = 53.82 + 3.81C. Some experimental conditions are also discussed in detail.

ISSN:0003-2719    

DOI:10.1080/00032719908543005

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A chemiluminescence (CL) system for menadione sodium bisulfite (MSB) combined with a flow-injection system is presented in this paper. It is based on CL produced by the oxidation of bisulfite liberated from MSB by Ce(IV). The system responds linearly to MSB concentration in the range of 0.01 ∼ 10 μg/mL with the detection limit (3τf) of 2 x 10−3μg/mL. The relative standard deviation for 2 μg/mL MSB was 3.45% (n=10). The system has been applied successfully to the determination of MSB in injections.

ISSN:0003-2719    

DOI:10.1080/00032719908543006

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

An Indirect AAS method has been developed for the determination of analgesic-inflammatory drugs, mefenamic acid, flufenamic acid and diclofenac sodium. The method depends on the complexation with copper (II) ammine sulphate. The complex was extracted into chloroform and the concentrations of substances were determined indirectly by AAS measurement of copper, after re-extraction into 0.3 N nitric acid solution. The developed method was applied to the assay of the drug substances in commercial tablet formulations. The results were statistically compared with those obtained by HPLC method by t- and F-tests at 95% confidence level. Calculated t and F values were both lower than the table values.

ISSN:0003-2719    

DOI:10.1080/00032719908543007

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A simple, sensitive and selective colorimetric method is described for the assay of ampicillin, amoxicillin, cephalexin, cefadroxil and cefaclor in their pharmaceutical preparations. The method is based on measuring the color obtained when the alkaline degradation products of these agents are allowed to react with ascorbic acid. The factors affecting the color generation and determination were studied and optimized. The reaction is selective to β-lactam antibiotics having amino acid side-chains with free amino functions and thus allow interference-free quantitation of some preparations containing these agents in combination with other β-lactam agents. The procedure is also successfully adopted as stability-indicating method for cephalosporins. A tentative mechanism of the color reaction is proposed.

ISSN:0003-2719    

DOI:10.1080/00032719908543008

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

C18-Silica used for Solid-Phase Extraction exhibits the same degree of adsorption of volatile hydrocarbons as compared to conventional Tenax adsorbent. The vapor pressure of the hydrocarbons and the velocity of the air sample through the sorbent are dominants of the preconcentration. Recovery of 80% for n-hexane and 98% for p-xylene at a concentration of 10 mg.m−3was obtained at 10 ml.g−.min−velocity.

ISSN:0003-2719    

DOI:10.1080/00032719908543009

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor