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A novel chemiluminescence (CL) flow sensor has been developed for the monitoring of iron(III). The analytical reagents involved in the CL reaction, including luminol and hexacyanoferrate(II) were both immobilized on an anion-exchange resin column. When sodium sulfate solution was passed through the column, these two reagents were eluted from the resins and then mixed with an iron(III) stream. By the fast reaction between iron(III) and hexacyanoferrate(II), the complex Prussian Blue was generated, which could catalyse the luminol oxidation by dissolved oxygen in alkaline aqueous solution to produce CL. The CL emission intensity was correlated with the standard iron(III) concentration in the range 0.01-Smgl−1, and the detection limit was 7 × 10−3mgl−1 iron(III). A complete analysis, including sampling and washing, could be performed in l 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 iron in blood samples. [ABSTRACT FROM AUTHOR]

An optosensing method for gadolinium based on the room-temperature phosphorescence behavior in aqueous solution induced by the transient adsorption of the complex formed by 1,4- bis (1′-phenyl-3′-methyl-5′-pyrazolone-4′-)butanedione (1,4) with Gd (III) on the chelating resin Chelex 100 (packed in a flow cell) is proposed. The proposed optosensing is satisfactory for the determination of the gadolinium ion in the range 8 × 10–7−5 × 10−5 M with a correlation coefficient of 0.995. The relative standard deviation was 2.0% for determination of 5× 10−6 M gadolinium ion ( n = 10). The response mechanism of the optosensing and the interferences of other lanthanide ions were also investigated. The method has been used to determine gadolinium ion in synthetic sample. [ABSTRACT FROM AUTHOR]

We have prepared toughened, porous, aminated polystyrene membranes that undergo an increase in reflectance as the pH increases from 6.8 to 8.0. Vinylbenzyl chloride (VBC) is copolymerized with divinylbenzene (DVB) in the presence of a toughening agent, Kraton G1652, a styrene-ethylene, butylene-styrene triblock copolymer, and a porogenic solvent, xylene/ dodecane. The optimum formulation for sensing is 2% DVB (mol DVB/mol VBC), 2% Kraton (g Kraton/g VBC) and 40% (v/v) 2∶1 xylene: dodecane. Benzoyl peroxide is used as the initiator. The components are partially polymerized at 85 °C to a viscosity of 600-800 centipoise. The polymerization is then stopped by reducing the temperature. A drop of the partially polymerized solution is confined between two microscope slides and the polymerization reaction is completed. The resulting membrane is then swollen in 1,4-dioxan and reacted with diethanolamine. These membranes have been incorporated into a pH sensor based on changes in reflected intensity measured through a bifurcated bundle of twenty unbuffered 50/55 core/cladding glass-on-glass optical fibers with numerical apertures of 0.57. The resulting sensor is stable and requires inexpensive optical components, a red-emitting LED as the source and a silicon photodiode as the detector. [ABSTRACT FROM AUTHOR]