163 resultados para Chemiluminescence

em Deakin Research Online - Australia


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A critical review presented is of the literature concerning the use of acidic solutions of potassium permanganate to generate chemiluminescence during the oxidation of both organic compounds and inorganic species. A brief overview of the reagent’s historical origin is followed by a chronological survey of its analytical applications, from what we believe to be the first report in 1975 through to those published up until mid-2001. This review does not include those papers where potassium permanganate has been used either in alkaline conditions or in conjunction with other chemiluminescence reagents.

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The oxidations of twenty five organic and inorganic species, with solublised manganese(IV), were found to elicit analytically useful chemiluminescence with detection limits (3 × S/N) for Mn(II), Fe(II), morphine and codeine of 5 × 10–8 M, 2.5 × 10–7 M, 7.5 × 10–8 M and 5 × 10–8 M, respectively. Additionally, the corrected spectra from four different analytes gave wavelengths of maximum emission in the range from 733 nm up to 740 nm suggesting that all these chemiluminescence reactions shared a common emitting species.

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We have developed a rapid and robust method for the determination of urea in spent haemodialysis fluid as a measure of the efficiency of haemodialysis treatments. A novel flow analysis instrument (which generates a pulsed solution flow) was coupled with a chemiluminescence detection system, based on the oxidation of urea with hypobromite. The ‘pulsed-flow chemiluminescence analyser’ exhibited high precision (1.6% relative standard deviation (R.S.D.) for a 1×10−5 M urea standard, n=10) and good limit of detection (9×10−7 M, S/N=3) as a result of the rapid and reproducible mixing of small volumes of reagent and sample at the point of detection. The proposed chemiluminescence technique and an established urease-based laboratory procedure were compared, and showed a very similar trend for the change in urea concentration during a typical haemodialysis treatment. The relative chemiluminescence response from the oxidation of species with similar structure has revealed the inherent selectivity of the light producing pathway, but a positive interference was obtained from protein when this technique was applied to the determination of urea in serum samples. Arginine was identified as the predominant source of this interference.

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This paper describes, for the first time, a simple and effective synthetic route for covalently bonding the chemiluminescence reagent, (4-[4-(dichloromethylsilanyl)-butyl]-4’-methyl-2,2’-bipyridyl)bis(2,2’-bipyridyl)ruthenium(II) onto silica particles. The subsequent preparation of chemically regeneratable detection cells and their preliminary analytical evaluation with both sequential injection analysis and flow injection analysis are also reported. Unoptimised analytical figures of merit were established for standard solutions of codeine and sodium oxalate with detection limits calculated from three times the standard deviation of the blank signal, of 1 × 10–8 M and 3 × 10–7 M respectively. The chemically immobilised reagent exhibited some intriguing solvent and kinetic effects, which are also briefly discussed.

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Semi-automated flow injection instrumentation, incorporating a small anion exchange column coupled with tris(2,2′-bipyridyl)ruthenium(II) (Ru(bipy)32+) chemiluminescence detection, was configured and utilised to develop rapid methodology for the determination of sodium oxalate in Bayer liquors. The elimination of both negative and positive interferences from aluminium(III) and, as yet, unknown concomitant organic species, respectively are discussed. The robustness of the methodology was considerably enhanced by using the temporally stable form of the chemiluminescence reagent, tris(2,2′-bipyridyl)ruthenium(III) perchlorate in dry acetonitrile. Real Bayer process samples were analysed and the results obtained compared well with those performed using standard methods within industrial laboratories.

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Flow injection methodology is described for the estimation of the total phenolic content of wine using acidic potassium permanganate chemiluminescence detection. Selected simple phenolic compounds including quercetin, rutin, catechin, epicatechin, ferulic acid, caffeic acid, gallic acid, 4-hydroxycinnamic acid and vanillin elicited analytically useful chemiluminescence with detection limits ranging between 4×10−10 and 7×10−7 M. A comparison between the chemiluminescence methodology and other total phenol/antioxidant assays, used by the food and beverage industry, resulted in a good correlation. The chemiluminescence detection was found to be selective with minimal interferences being observed from the non-phenolic components in wine. Analysis of 12 different wines showed that the chemiluminescence method was a rapid way to estimate their antioxidant or total phenolic content.

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The determination of the amino acids proline, histidine, tyrosine, arginine, phenylalanine and tryptophan using flow injection analysis (FIA) with chemiluminescence detection is described. Proline was the only amino acid to exhibit chemiluminescence with the tris(2,2-bipyridyl)ruthenium(III) reaction at pH 10. While, histidine was found to selectively enhance the reaction of luminol with Mn(II) salts in a basic medium. Acidic potassium permanganate chemiluminescence was able to selectively determine tyrosine at pH 6.75. Low pressure separations using a C18 guard column allowed the simultaneous determination of tyrosine and tryptophan or phenylalanine and tryptophan with acidic potassium permanganate and copper(II)–amino acid–hydrogen peroxide chemiluminescence, respectively. Precision for each method was less than 3.9% (R.S.D.) for five replicates of a standard (1×10−5 M) and the detection limits ranged between 4×10−9 and 7×10−6 M. Preliminary investigations revealed that the methodology developed was able to selectively determine the individual amino acids in an equimolar mixture of the 20 naturally occurring amino acids.

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A simple model peroxyoxalate chemiluminescence system was monitored directly across a range of temperatures (from −80 to +20 °C) using 13C nuclear magnetic resonance spectroscopy. These experiments were made possible by the utilisation of 13C doubly labelled oxalyl chloride, which was reacted with anhydrous hydrogen peroxide in dry tetrahydrofuran. Ab initio quantum calculations were also performed to estimate the 13C nuclear magnetic resonance (NMR) shift of the most commonly postulated key intermediate 1,2-dioxetanedione and this data, in concert with the spectroscopic evidence, confirmed its presence during the reaction.

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The mono-isopropylamine salt of glyphosate was selectively determined directly in industrial and commercial formulations using flow injection analysis with tris(2,2′-bipyridyl)ruthenium(II) chemiluminescence detection without the need for separation. Glyphosate and its mono-isopropylamine salt furnished detection limits of 7×10−9 and 3.5×10−10 M and relative standard deviations of 0.4% at 1×10−7 M and 0.8% at 5×10−8 M, respectively. The methodology is robust and reliable with samples subjected only to aqueous dilution prior to analysis.

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Flow injection methodology is described for the determination of proline in red and white wines using tris(2,2′-bipyridyl)ruthenium(II) chemiluminescence detection. Selective conditions were achieved for proline at pH 10, while other amino acids and wine components did not interfere. The precision of the method was less than 1.00% (R.S.D.) for five replicates of a standard (4 × 10−6 M) and the detection limit was 1 × 10−8 M. The level of proline in white and sparkling wines using the developed methodology was equivalent to those achieved using HPLC-FMOC amino acid analysis. SPE removal of phenolic material was required for red wines to minimize Ru(bipy)33+ consumption and its associated effect on accuracy.

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The limits of detection (3s) for ascorbic acid were 5×10−8 M with acidic potassium permanganate using both flow injection analysis (FIA) and sequential injection analysis (SIA) whereas the soluble manganese(IV) afforded 1×10−8 M and 5×10−9 M for FIA and SIA, respectively. Determinations of ascorbic acid in Vitamin C tablets were achieved with minimal sample pretreatment using a standard additions calibration and gave good agreement with those of iodimetric titration.

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This paper describes a dual chemiluminescence reagent for the determination of the opiate alkaloids morphine, codeine, oripavine, and thebaine in Papaver somniferum extracts. Detection was achieved using a mixture of acidic potassium permanganate and tris(2,2′-bipyridyl)ruthenium(ii), where the former acted as both the oxidant for the latter and as a chemiluminescence reagent in its own right. The analytes were separated on a C8 column using ion-pairing HPLC. The application of the mixed reagent detection compared favourably with results obtained using standard HPLC methodology. Detection limits for the alkaloids were 10-6, 5 × 10-7, 3 × 10-6, and 2 × 10-6 mol L-1 for morphine, codeine, oripavine, and thebaine, respectively.

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The spectral distribution for the chemiluminescent oxidation of ammonia with hypobromite is significantly different to that for the oxidation of ammonia with N-bromosuccinimide. Therefore, in contrast to the assumptions of several authors, the action of N-bromosuccinimide is not solely derived from the in situ formation of hypobromite. Neither the oxidation of urea with hypobromite nor the oxidation of urea with N-bromosuccinimide involves an initial hydrolysis of urea to ammonia in the alkaline solution. However, these two reactions lead to a common emitter. The addition of xanthene dyes, such as dichlorofluorescein, enhance the chemiluminescence intensity by energy transfer to the efficient fluorophore, but reaction between the sensitiser and hypobromite can result in a significant increase in the background signal. A list of potential interferences has been compiled; particular attention was paid to guanidino compounds, as the chemiluminescence accompanying the oxidation of this functional group has not been previously discussed.

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The Sakaguchi reaction between arginine and hypohalites in the presence of α-phenols (Fig. 1) has been extensively employed for the colorimetric determination of this amino acid [1] M.A Parniak, G Lange and T Viswanatha, Quantitative determination of monosubstituted guanidines: a comparative study of different procedures, J. Biochem. Biophys. Methods 7 (1983), pp. 267–276. Abstract | View Record in Scopus | Cited By in Scopus (8)[1] and [2]. There have been a number of modifications to the reaction for the determination of arginine to improve the color stability and sensitivity. The Sakaguchi reaction is much faster with hypobromite than with hypochlorite, but the colored product fades at a higher rate; however, this can be prevented by adding urea to remove the excess hypobromite [3]. Although 1-naphthol was originally used as the chromogen, other phenols including 2,4-dichloro-1-naphthol [4], 8-quinolinol [5], 5-chloro-7-iodo-8-quinolinol [6], and thymol [2] (Fig. 1) have provided superior analytical figures of merit. We have found that the reaction between arginine and hypobromite is chemiluminescent [7], which has been used to develop an analytical procedure that is rapid, simple, and selective for arginine in the presence of other amino acids.