Applications of permanganate chemiluminescence to the analysis of food components
Chemiluminescent oxidations with manganese reagents have been investigated using flow and spectroscopic techniques. An assay has been developed for ascorbic acid using the chemiluminescent oxidation of ascorbic acid with permanganate in acid medium. The assay has a linear range of 5xl 0-7 to 1 X, 0-3 mol dM-3 and has been applied to a range of food supplements and fruit juices. The addition of a manganese (11) catalyst extends the applicability of acid permanganate to the determination of sugars and polyhydric alcohols. The reaction has been optimised for the determination of mono and disaccharides in a flow injection system. Development of a reagent based on manganese (111)i,n a methanol and sulphuric acid solution, has further extended the scope of the reaction enabling the determination of fructose in the range 1 X1 0-7 to 1 X1 0-3 mol d M-3. The reagent has successfully been used in post column detection with HPLC. It has been established that the light emission occurs after manganese (VII) has been reduced and appears to be connected with the production and disappearance of Mn (111). Chemiluminescence spectroscopy has shown that the spectra are the same for a large number of aliphatic and aromatic polyhydroxy compounds. The spectrum remains the same whether the oxidising reagent is Mn (VII), Mn (IV) or Mn (111)i,n dicating that the same emitting species is involved in all these reactions and that it involves Mn(III) and/or Mn(II).