Enhanced permanganate chemiluminescence

Abstract

The significant enhancement of acidic potassium permanganate chemiluminescence by Mn(II) results from the concomitant presence of permanganate and Mn(III) in the reagent solution, which enables rapid production of the excited Mn(II) emitter with a wide range of analytes. Furthermore, the key Mn(III) co-reactant can be quickly generated by reducing permanganate with sodium thiosulfate, instead of the slow (~24 h) equilibration required when Mn(ii) is used. The emission from reactions with analytes such as tyrosine and fenoterol was over two orders of magnitude more intense than with the traditional permanganate reagent.

Chemiluminescence detection flow cells for flow injection analysis and high-performance liquid chromatography

“…Using FIA methodology, the analytes were injected (ten replicates) into a water carrier stream, which merged with the permanganate reagent at a flow rate of 3.5 mL min −1 per line. In agreement with our previous work [29], the enhanced reagent provided a considerable increase in chemiluminescence intensity (4-to 5-fold for morphine and 32-to 38-fold for amoxicillin for most flow cells; Table S1 in the ESM). Greater enhancement was observed for flow cells F and H (7-fold for morphine and 50-to 58-fold for amoxicillin), where the merging of reactants within the detection zone enabled a greater proportion of the light emitted from these reactions to be captured.…”

“…7; Table S3 in the ESM), with discrepancies between the two experimental approaches attributable to differences in flow rates and the proportion of organic modifier in the carrier/eluent stream. The limits of detection for the five analytes using FIA under these conditions (with flow cell H) ranged from 1× 10 −10 to 5× 10 −9 M (compared with 3×10 −8 to 1×10 −7 M using the standard permanganate reagent; Table S4 in the ESM), which were better than all previously reported values for epinephrine, isoprenaline, salbutamol and fenoterol using permanganate chemiluminescence systems [29,[41][42][43][44][45]. Metaproterenol had not previously been detected with these reagents.…”

“…Our previous investigations involving these and other analytes have shown that considerable increases in reaction rate and chemiluminescence intensity can be obtained by a preliminary partial reduction of permanganate to create a stable, relatively high concentration of Mn(III) in the reagent solution [29,36]. The flow cells were therefore also compared with the 'enhanced' permanganate reactions as examples of extremely rapid chemiluminescence systems.…”

“…As only fenoterol had previously been detected with the enhanced reagent [29], we optimised the concentrations of permanganate and thiosulfate required to generate the greatest chemiluminescence intensities with each analyte using FIA (Fig. S4 in the ESM), prior to implementing this detection system in HPLC.…”

“…The 'standard' permanganate reagent was prepared by dissolution of potassium permanganate (1×10 −3 M) in 1% (m/v) sodium polyphosphate and adjusting to pH 2.5 with sulfuric [29].…”