摘要:

A newly synthesized crown ether ionophore can differentiate betweenR-(+) andS-(-)-1-phenylethylammonium ions when incorporated into a plasticized PVC based electrode membrane, thus providing enantiomer-selectivity. Different membrane compositions were studied. The selectivity coefficient found was 0.71, independent of the membrane composition. This proves the robustness of the ISE method for testing the enantiomeric selectivity of newly synthesized ionophores. Selectivities of the new ionophore towards different hydrophilic cations were also determined.

ISSN:0003-2719    

DOI:10.1080/00032719708001680

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Three new ISFET devices (ion-selective field effect transistor) based on polymeric selective membranes sensitive to cationic surfactants have been fabricated and characterised. These new sensors use a PVC-sebacate matrix incorporating benzyldimethyl-hexadecylammonium reineckate, dodecyltrimethyl-ammonium reineckate and hexadecylpyridinium phosphotungstate, respectively, as exchanger.

ISSN:0003-2719    

DOI:10.1080/00032719708001681

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

An amperometric enzyme electrode for glucose has been prepared by immobilized glucose oxidase (GOD) in a multilayer film based on a thiol self-assembled monolayer at a gold electrode. The multilayer film of GOD and ferrocene attached poly(4-vinylpyridine) (Fc-PVP) complex is formed by electrostatic force. Fc-PVP as a polyelectrolyte in which ferrocene is as a mediator, acts with GOD to form a complex. The linear range of the enzyme electrode is extended up to 10mmol/L of glucose due to the addition of 5 GOD layers. The enzyme electrode is sensitive to glucose, 0.10 mmol/L glucose leads to a response current of 22nA and the detection limit is down to 0.01mmol/L. Ascorbic acid and uric acid have no interference for the determination of glucose. The enzyme electrode is stable over 3 weeks.

ISSN:0003-2719    

DOI:10.1080/00032719708001682

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A poly(indole-3-acetic acid) chemically modified electrode offers substantial improvements in voltammetric sensitivity and selectivity towards dopamine (DA). This polymer coating greatly attenuates the voltammetric response of ascorbic acid (AA) while the oxidation peak current of DA is enhanced by over an order of magnitude compared with that at the bare electrode. The high sensitivity and selectivity for DA appears to be mainly due to the charge discrimination and the analyte accumulation. The current response is dependent on both the solution pH and accumulation time. The detection limit is ca. 6.0×10−8mol/L. In 1.0×10−6M dopamine solution, AA shows no interference although its concentration is larger by 3 orders. The modified electrode is rather stable; a reproducible response of DA is obtained even after a month.

ISSN:0003-2719    

DOI:10.1080/00032719708001683

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The construction and analytical evaluation of coated-graphite saccharin ion-selective electrodes, based on the ion pair formed between saccharinate anion and basic dye cations incorporated in a poly(vinylchloride)(PVC) matrix, are described. Several basic dyes such as brilliant green, crystal violet, malachite green, methylene blue, Nile blue, rhodamine B, toluidine blue O, Victoria blue B and violet gentian were used in the preparation of the coated electrodes as anion-exchanger. Of those, only electrodes constructed with toluidine blue O, methylene blue, violet gentian and rhodamine B presented good responses. The influences of membrane composition, pH and foreign food additives were investigated. The best electrode found was 5:30:65%m/m (toluidine blue O cation)(saccharinate anion)/dibutylphthalate/PVC, respectively.

ISSN:0003-2719    

DOI:10.1080/00032719708001684

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A novel procedure for the measurement of D-isocitrate is described that utilizes the fluorescence quenching of thionine by the reduced form of the cofactor NADPH, which results from the isocitrate dehydrogenase-catalyzed conversion of D-isocitrate to 2-oxoglutarate. The procedure is termed substrate induced-quenching (SIQ) assay and results in a fluorescence-quenching constant (KSIQ) of 4443 M−1obtained from data collected over the range of 0–500 μM isocitrate.

ISSN:0003-2719    

DOI:10.1080/00032719708001685

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The purpose of this study was the quantitative determination of solid dosage forms containing tenoxicam (TNX) by IR spectrophotometry, using the KBr disc technique. Dehydrocholic acid (DHCA) was used as the internal standard. The specific absorption bands at 1420 cm−1and 1705 cm−1were chosen for TNX and DHCA, respectively.

ISSN:0003-2719    

DOI:10.1080/00032719708001686

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

β-Cyclodextrin polymer (β-CDP) adsorbed resin phase spectrophotometry with 1- (2-pyridylazo) -2-naphthol (PAN) has been developed for determination of copper at the μg level in soybean and human hair. Cobalt, nickel, zinc and manganese, which form colored species with PAN in the resin phase, can be completely masked with a solution composed of phenanthroline (2.78×10−5mol/1) and sodium hexametaphosphate (3.27×10−3mol/1).

ISSN:0003-2719    

DOI:10.1080/00032719708001687

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Di-isopropyl methylphosphonate (DIMP) and dimethyl methylphosphonate (DMMP), which are manufacturing by-products of. and surrogate compounds for, the nerve agents Sarin (GB) and VX, respectively, are readily quantitated at microgram per liter concentrations in contaminated groundwaters. Aqueous samples (typically 1 L) are first fortified with triethylphosphate (TEP) as a surrogate, then passed through a “sandwiched” set of three preconditioned extraction disks consisting of the following (in filtration order): (a) glass fiber filter, to remove unwanted particulate matter; (b) C18-based extraction disk, to collect DIMP; and (c) carbon-based extraction disk, to collect DMMP. The glass fiber filter is discarded; the two extraction disks are dried and extracted with a small volume of methanol. After the extract is fortified with diethyl ethylphosphonate (DEEP) internal standard, it is analyzed using a gas chromatograph equipped with a nitrogen-phosphorus detector (NPD). Quantitation of DMMP, DIMP, and TEP is performed using the method of internal standards.

ISSN:0003-2719    

DOI:10.1080/00032719708001688

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A comparative study was carried out to determine 21 pesticides in environmental water samples by high performance liquid chromatography using both liquid-liquid (LLE) and solid-phase (SPE) extractions. The reproducibility of the SPE method is better than employing LLE with dichloromethane. but SPE was more efficient to recover metomyl, dimethoate, chlorpyrifos ethyl and carbophenothion.

ISSN:0003-2719    

DOI:10.1080/00032719708001689

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor