摘要:

Polymer-modified electrodes are one of the most rapidly growing areas of modern electrochemistry. These electrodes have aroused intense interest due to their inherent advantages such as simple and economic fabrication, fast and sensitive response, low resistance and high antifouling performance. A number of sensors have been developed for the direct potentiometric determination of ions in aqueous solution based on a correlation between a selective response and doping of the anion in the polymers. We report herein a new sensor modified with poly(methylthiophene-methylpyrrole) copolymer. This modified electrode shows near Nernstian response for Br−over a concentration range of 10−4to 10−1M. The electrode response also exhibits a sharp endpoint response for the potentiometric titration of Br−.

ISSN:0003-2719    

DOI:10.1080/00032719708002285

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A novel chemiluminescence(CL) sensor combined with flow-injection analysis has been developed for determining free chlorine in tap water. The analytical reagent luminol was immobilized on an anion exchange resin column. While a volumn of sodium hydroxide passed through the column, luminol was eluted from the resin in alkaline aqueous solution and then mixed with a sample stream to react and produce CL. The CL emission intensity was correlated with the standard ClO−concentration in the range 1×10−8to 4×10−5g ml−1, and the detection limit was 8×10−9g ml−1ClO−. Interfering metal ions present in water were effectively separated by a pre-column cation exchanger. A complete analysis, including sampling and washing, could be performed in 1 min with a relative standard deviation of less than 5%. The sensor was stable for over 200 times and has been applied successfully to the determination of ClO−in tap water.

ISSN:0003-2719    

DOI:10.1080/00032719708002286

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Flow analysis methodology is presented for the determination of micromolar levels of aqueous hydrogen peroxide by luminol chemiluminescence. Adjustment of the pH to alkaline conditions and addition of the luminophore are implemented using in-line flow-through beds containing crystalline media. The requirement for a homogeneous catalyst is eliminated by electrochemical initiation of luminescence. Traditional laboratory reagents are replaced by packed beds containing solid phase basification media, and crystalline luminol. The methodology is suitable for application in both continuous flow and flow injection analysis configurations.

ISSN:0003-2719    

DOI:10.1080/00032719708002287

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Lipophilic anionic dichlorofluorescein ester was examined as a chromophore for the development of polymeric film based optical sensors for calcium. A calcium organophosphate salt and a neutral ionophore were employed as the active component for calcium sensing. The response pH. dynamic range, detection limit and selectivities are governed by the calcium carrier as well as the membrane plasticizer. The membrane that uses the anionic chromophore and the calcium organophosphate salt responds to calcium in the range of 1.0 × 10−6to 0.2 M at pH 7.4.

ISSN:0003-2719    

DOI:10.1080/00032719708002288

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Plasticized poly(vinyl chloride) (PVC) membranes incorporating dealkylcalix[6]arene as a sensory material were developed for the determination of glucose after itsin situderivatization with a lipophilic Girard's P′ reagent. In a TRIS-HCl buffer at pH 9.0, the electrode exhibits a near Nernstian response in the range 1.0 × 10−4- 0.01 mol l−1glucose with a slope of 45.5 mV per concentration decade. The electrode has a fast response time and a long working lifetime. The selectivity and sensitivity of this electrode method allow its application to the assay of glucose concentration in human blood samples.

ISSN:0003-2719    

DOI:10.1080/00032719708002289

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A reliable enzymatic procedure has been devised for the determination of glycerol-3-phosphate and glycero-phosphorylcholine based on spectrophotometry. Glycerol-3-phosphate oxidase and phospholipase-D enzymes are used to produce hydrogen peroxide to oxidize iodide into triiodide at an elevated pH in the presence of Mo(VI), and the absorbance of the triiodide was read at 352 nm.

ISSN:0003-2719    

DOI:10.1080/00032719708002290

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A sensitive and rapid extraction-spectrophotometric method for the determination of betamethasone, based on the formation of a charge transfer complex with benzocaprol red (I) and acid ethyl blue (II) is described. The calibration graph, resulting from the measurement of the absorbance of the chloroform and benzene extracts (10 ml) at 588 and 677 nm using I and II. respectively, is linear over the range 0–16 and 0–20 μg ml−1of betamethasone with relative standard deviations (R.S.D.) of 1.6 and 1.3% for 5 μg ml−1betamethasone using reagents I and II, respectively. For more accurate results. Ringbom optimum concentration ranges were found to be 2–14 and 2–17.5 μg ml−1using reagents 1 and II, respectively. The method was satisfactorily applied to the determination of betamethasone and its esters in pharmaceutical preparations and found in good agreement with the British Pharmacopeia (1993) method.

ISSN:0003-2719    

DOI:10.1080/00032719708002291

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A new sensitive, fast thin layer chromatography-fluorescence scanning densitometry(TLC-F) method is described for the simultaneous determination of doxycycline(DOTC), tetracycline(TC) and oxytetracycline(OTC). With a mobile phase chloroform: methanol:acetone: 1% aqueous ammonia(10:22:50:18, V/V) and a silica gel thin-layer, previously treated with 0.27 mol/L sodium EDTA solution adjusted to pH 9.0, all the tetracyclines were separated from each other. The Rf values are 0.52,0.35,0.21 for DOTC, TC and OTC, respectively. The fluorescent spots were scanned with a spectrodensitometer using 365nm as the excitation wavelength and the cut-off filter was set at 440nm. The linear ranges are 0.50∼25.6ng for DOTC; 0.96∼96.2ng for TC and 0.50∼49.6ng for OTC. The relative standard deviations(RSDs) are all <3.5%. The recoveries of them in honey, serum and urine are 94.5%∼107%.

ISSN:0003-2719    

DOI:10.1080/00032719708002292

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

An extractive-spectrophotometric study based on the reaction of furosemide with 1,2-naphthoquinone-4-sulphonate (NQS) is described. Optimal conditions are: NaH2PO4-Na2HPO4pH 7.5, NQS 7.7×10−3M, heating 30 min at 70° C and isoamyl alcohol as extractant. The method is used to determine furosemide in pharmaceutical samples. The interference caused by lactose can be eliminated using pH 4.5. The method can be also used to determine lactose at pHs 4.5 and 7.5.

ISSN:0003-2719    

DOI:10.1080/00032719708002293

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Chlorpromazine hydrochloride reacts with cerium ammonium nitrate to give a pink colour having maximum absorbance at 530 nm. The reaction is selective for chlorpromazine, with 0.001 mg/ml as visual limit of quantitation, and provides a basis for a new spectrophotometric determination. The colour reaction obeys Beer's Law from 0.001 mg to 0.5 mg/ml of chlorpromazine. The standard deviation does not exceed 0.050. The method was successfully applied to pure and pharmaceutical dosage forms of chlorpromazine. The quantitative assessment of tolerable limits of other drugs was also studied.

ISSN:0003-2719    

DOI:10.1080/00032719708002294

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor