A novel histidine assay using tetraphenylporphyrin manganese (III) chloride as a molecular recognition probe by resonance light scattering technique Original Research Article

A novel histidine-selective method has been developed for the determination of histidine in aqueous solutions by resonance light scattering (RLS) technique. At pH 8.0, the weak RLS intensity of tetraphenylporphyrin manganese (III) chloride [MnTPPCl] was greatly enhanced by the addition of histidine with the maximum peak located at 483 nm. Under the optimum conditions, it was found that the enhanced RLS intensity was in proportion to the concentration of histidine in the range 7.8 × 10−7–2.4 × 10−5 mol l−1. Low detection limit of 9.2 × 10-8 mol l−1 has been achieved. The histidine concentrations in synthetic samples and real samples were determined with satisfactory results. The sensitivity and selectivity of this method are high enough to permit the determination of trace amounts of histidine without any significant interference from high levels of other components such as common anions and especially, other amino acids.