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Analytical data on element concentrations in plastics is an important prerequisite for the recycling of technical waste plastics. The chemical resistance and high additive contents of such materials place a high demand on analytical methods for quantifying elements in thermoplastics from electrotechnical applications. The applicability of three common independent analytical methods (EDXRF, AAS, ICP-AES)...
Mercury (II) ion-selective PVC membrane sensor based on ethyl-2-benzoyl-2-phenylcarbamoyl acetate (EBPCA) as a novel nitrogen containing sensing material is successfully developed. The sensor exhibits good linear response of 30 mV per decade within the concentration range 10 -6 -10 -3 mol l -1 Hg(II). The sensor shows good selectivity for mercury (II) ion in...
The identities of the species of chromium(VI) that are present in aqueous solution, their spectra and their equilibria, continue to be a subject of discussion in the literature. In this paper, the composition of the Cr(VI) equilibria was estimated from the UV-vis spectra of dilute potassium dichromate solutions, without any prior knowledge of the quantities of pure components, with the aid of Imbrie...
A nafion film coated glassy carbon electrode (NFGCE) was employed for the determination of paraquat. Paraquat was accumulated onto NFGCE by the cation-exchange feature of nafion at open circuit potential in basic medium followed by cathodic differential pulse voltammetric (CDPV) determination in a medium containing permanganate ions. The sensitivity for the determination of paraquat was improved through...
On-line photochemical reaction of reserpine in the presence of acetone was investigated. Acetone was found to speed up the on-line photochemical conversion of reserpine into an intensively fluorescent compound. Not only reaction acidity but also the acetate buffer concentration affected the on-line photochemical induced fluorescence signal. Based on the observation an automated flow injection photochemical...
A potentiometric method is described for the determination of cetylpyridinium (CP) cation using a polyvinyl chloride powder (PVC) membrane sensor based on CP-iodomercurate ion pair as an electroactive material. The sensor shows a linear response for CP ion over the concentration range of 2x10 -6 -1x10 -3 M at 25 o C. The electrode posses a sub-Nernstian slope of 29...
The present paper deals with the selection of variables for the H-point and generalised H-point standard additions methods (HPSAM and GHPSAM, respectively). Both methods are applied for the resolution of spectroscopic interfered signals in the UV-vis range. The HPSAM is a suitable method for the resolution of binary and ternary mixtures when the interferent is known. The GHPSAM is applied for the...
The construction of a l-lysine biosensor on a Si-gold strip electrode (SGSE) is described in this study. The construction comprises (a) the formation of poly(o-phenylenediamine, o-PD) membrane on the electrode surface via electropolymerization and (b) the immobilization of lysine oxidase on the gold/poly(o-PD) electrode with glutaraldehyde. The behavior of the gold/poly(o-PD) electrode against H ...
In situ generated Ru(bpy) 33+ -based chemiluminescence (CL) detection will be shown to be compatible with micellar electrokinetic chromatography (MEKC) providing significant advantages over other Ru 3+ generation protocols. The CL reagent, Ru(bpy) 32+ is continuously added post-capillary to avoid precipitating the anionic surfactant used to enhance...
Under controlling pH 3, R-(+)- and S-(-)-ofloxacin (OFLX) enantiomers can be well recognized and resolved by the synchronization-1st derivative fluorescence spectroscopic techniques, and the interference from urine blank also can be eliminated. The linear dynamic ranges are 0.36-2.16 (R), 0.36-2.89 and 3.16-31.6 μg/ml (S), respectively, for determining OFLX in urine samples. The limits of detection...
A simple and sensitive spectrophotometric method for determination of copper(II) is based on the formation of a blue coloured complex of Cu(II) with 9-phenyl-2,3,7-trihydroxy-6-fluorone (PF) in the presence of cetylpyridinium chloride (CP) and Triton X-100, has been developed. Optimum concentrations of PF, CP, Triton X-100 and pH ensuring maximum absorbance were defined. The complex Cu(II)-PF-CP-Triton...
A simple indirect spectrophotometric method for the determination of cyanide, based on the oxidation of the cyanide with chlorine (Cl 2 ) is described. The residual chlorine is determined by the color reaction with o-tolidine (3,3'-dimethylbenzidine). The maximum absorbance for Cl 2 is at 437 nm. A linear calibration graph (0-4.0x10 -5 M CN - ) is obtained under...
A sequential injection system was proposed to accomplish the potentiometric determination of urea. This procedure used an ammonium tubular selective electrode to assess ammonium concentration produced by enzymatic hydrolysis of urea from Jack bean meal (Canavalia ensiformis DC) crude extract. A gaseous diffusion device was coupled to the flow set-up allowing on-line sampling and suitable selectivity...
This paper reports a continuous flow-based spectrophotometric method for the determination of paracetamol in pharmaceuticals. Dilute samples containing paracetamol are continuously hydrolysed in an alkaline medium, using a household microwave oven, to p-aminophenol, which reacts with o-cresol in 3.5 M NaOH. The blue derivative thus formed exhibits an absorbance maximum at 620 nm. The detection limit...
Screen-printed electrodes coated with the nafion layer have been investigated for cholinesterase biosensor design. The butyrylcholinesterase (ChE) from horse serum was immobilised onto the nafion layer by cross-linking with glutaraldehyde vapours. The biosensors obtained showed better long-term stability and lower working potential in comparison to those obtained with no nafion coating. The sensitivity...
In this paper, a sample preparation method based on acid extraction of magnesium, manganese and zinc from plant tissue by means of high intensity probe ultrasonication is described. Acid extracts obtained upon sonication were directly nebulised into an air-acetylene flame for fast metal determination by atomic absorption spectrometry. Parameters influencing extraction such as sonication time, ultrasound...
A study into the sonoelectroanalysis of silver at a highly boron-doped diamond electrode is presented, exploring the benefits of the introduction of power ultrasound and new electrode materials into classical electrochemical techniques. Both cathodic and anodic stripping voltammetry have been investigated in terms of their analytical suitability towards silver detection. Cathodic stripping voltammetry,...
An analytic method for the determination of phenoxy acid herbicides and 2,4-D esters in soil samples by GC-FID is described. The esterification reaction with MeOH and H 2 SO 4 as catalyst has been used, optimizing experimental variables by the 'Simplex method'. The recoveries in soil samples were between 76 and 97% with relative S.D.s between 4 and 7% (n=4) at level of concentration...
Evidence of element speciation in biological fluids is scarce and fragmentary in the literature. On the other hand, it is well known that chemical speciation analysis is prone to error due to contamination, modification or breaking up of the metal-organic moiety link during the separation processes, as well as to insufficient detection power for element quantification in the various fractions. Therefore,...
A method based on capillary electrophoresis with electrochemical detection (CE-ED) was developed for the determination of baicalein, baicalin and quercetin in Scutellariae Radix and its pharmaceutical preparations. The effects of some important factors such as the acidity and concentration of running buffer, separation voltage, injection time, and the potential of working electrode were investigated...
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