Neil W. Barnett

Analytical applications of tris(2,2′-bipyridyl)ruthenium(III) as a chemiluminescent reagent

Abstract This paper reviews the analytical applications of the chemiluminescence reactions involving tris(2,2′-bipyridyl)ruthenium(III), from the earliest paper in 1978 to mid 1998. After an introduction which briefly describes historical perspectives, spectroscopic and mechanistic considerations, the review is divided into two major sections. The first section discusses the methods of generation of tris(2,2′-bipyridyl)ruthenium(III) reagent, including chemical/photochemical, electrochemical and in situ electrochemiluminescence methods. The second section describes the applications of this reagent to analysis under broad classifications according to the type of analyte determined. Entries for indirect methods, immunoassay and DNA probe assays have also been included.

Sequential injection analysis

This article provides a basic overview of the principles of sequential injection analysis. This is followed by a discussion of the instrumental requirements. A brief overview of some of the diverse analytical applications of SIA is also presented.

Analytical applications of acidic potassium permanganate as a chemiluminescence reagent

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.

A potential-controlled switch on/off mechanism for selective excitation in mixed electrochemiluminescent systems

We demonstrate the complete, rapid, and reversible switching between the emissions from two electrogenerated chemiluminescence (ECL) systems contained within the same solution, controlled by simple modification of the applied potential. The fundamental bases of the approach are the ability to selectively ‘switch on’ luminophores at distinct oxidation potentials, and an intriguing observation that the emission from the well-known electrochemiluminescent complex, fac-Ir(ppy)3, (where ppy is 2-phenylpyridinato), can be selectively ‘switched-off’ at high overpotentials. The dependence of this phenomenon on high concentrations of the co-reactant implicates quenching of the excited [Ir(ppy)3]* state by electron transfer. Rapid spectral scanning during modulation of the applied potential reveals well resolved maxima for mixtures comprising either green and red or green and blue luminophores, illustrating the vast potential of this approach for multiplexed ECL detection.

Determination of codeine in process streams using flow-injection analysis with chemiluminescence detection

A flow-injection (FI) methodology using tris(2,2′-bipyridyl)ruthenium(II) chemiluminescence was developed and evaluated for the determination of codeine in process streams. For the samples analysed codeine exhibited high sensitivity and selectivity over various other similar Papaver alkaloids, especially morphine (104 times more sensitive). A simple, computer controlled FI manifold incorporating a heterogenous lead dioxide/silica reactor was utilised to analyse an artificial sample and two process samples. The results were compared with those obtained by an established ion-pair liquid chromatography (LC) method. Calibration was linear between 1.0 × 10−8 to 1.0 × 10−6M with a 3σ detection limit of 5 × 10−9M. The internal calibration method compared most favourably with the LC determinations which highlighted complicated matrix effects observed at differing process sample points. The efficacy of the solid phase reactor and the suitability of the methodology for application to continuous on-line analysis of codeine process streams was assessed.

Chemically induced phosphorescence from manganese(II) during the oxidation of various compounds by manganese(III), (IV) break and (VII) in acidic aqueous solutions

Chemiluminescence was observed during the manganese(III), (IV) and (VII) oxidations of sodium tetrahydroborate, sodium dithionite, sodium sulfite and hydrazine sulfate in acidic aqueous solution. From the corrected chemiluminescence spectra, the wavelengths of maximum emission were 689±5 and 734±5 nm when the reactions were performed in sodium hexametaphosphate and sodium dihydrogenorthophosphate/ orthophosphoric acid environments, respectively. The corrected phosphorescence spectrum of manganese(II) sulfate in a solution of sodium hexametaphosphate at 77 K exhibited two peaks with maxima at 688 and 730 nm. The chemical and spectroscopic evidence presented strongly supported the postulation that the emission was an example of solution-phase chemically induced phosphorescence of manganese(II) thereby, confirming earlier predictions that the chemiluminescence from acidic potassium permanganate reactions originated from an excited manganese(II) species.

Capillary electrophoresis for forensic drug analysis: A review.

This paper reviews recent applications of capillary electrophoresis to forensic drug analysis and covers the literature since 2001. A brief overview of capillary electrophoresis is followed by a discussion of analytical applications which have been categorized into two sections: (i) drug seizures and non-biological samples, and (ii) forensic toxicology and biological samples.

Monitoring the total phenolic/antioxidant levels in wine using flow injection analysis with acidic potassium permanganate chemiluminescence detection

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.

Selective Excitation of Concomitant Electrochemiluminophores: Tuning Emission Color by Electrode Potential†

ECL in 3D: Selective electrogenerated chemiluminescence (ECL) of several ruthenium and iridium complexes simultaneously in solution can be controlled by electrode potential (see picture; λem=emission wavelength). These luminescent redox systems create a range of new possibilities for multi-analyte ECL detection, assessment of interdependent electrochemical/spectroscopic properties, and color tuning in light-emitting devices.

Direct Detection of Biologically Significant Thiols and Disulfides with Manganese(IV) Chemiluminescence

The quantification of low-molecular mass thiols and disulfides involved in cellular redox processes is hindered by oxidation or degradation of analytes during conventional sample preparation steps (including deproteinization and derivatization). Researchers therefore seek techniques that minimize sample handling and permit direct detection of thiols and disulfides within a single chromatographic separation. We demonstrate a new HPLC procedure for these biologically important analytes that incorporates direct chemiluminescence detection with a manganese(IV) reagent. A mixture of seven thiols and disulfides (cysteine, N-acetylcysteine, homocysteine, glutathione (GSH), glutathione disulfide (GSSG), cystine, and homocystine) in their native forms were separated using a C18 column within 20 min. Detection limits for these analytes ranged from 5 × 10(-8) to 1 × 10(-7) M, and the precision for retention times and peak areas was excellent, with relative standard deviations of less than 0.3% and 2%, respectively. This approach was employed to determine two key biomarkers of oxidative stress, GSH and GSSG, in whole blood taken from 12 healthy volunteers. Samples were deproteinized, centrifuged, and diluted prior to analysis using a simple procedure that was shown to avoid significant artificial oxidation of GSH.