Spectrophotometric method for the determination of manganese with phenylfluorone in the presence of Triton X-100 and cetylpyridinium chloride in pharmacological preparations and vegetable fertilizers

A simple and very sensitive method for the spectrophotometric determination of manganese in pharmacological preparations and vegetable fertilizers is proposed. The method is based on the formation of a blue coloured complex of Mn (II) with 9-phenyl-2,3,7-trihydroxy-6-fluorone (PF) in the presence of cetylpyridinium chloride (CP) and Triton X-100. Optimum concentrations of PF, CP, Triton X-100 and pH ensuring maximum absorbance were defined. The complex Mn(II)-PF-CP-Triton X-100 shows maximum absorbance at 591 nm with the molar absorptivity value 1.77×105 L mol−1 cm−1. The detection limit of the method is 0.004 μg mL–1. The Beer's law is obeyed for manganese concentrations in the range 0.02–0.2 μg mL−1. The effect of foreign ions was elucidated. The statistical evaluation of the method was carried out for six determination using 5 μg Mn and the following results were obtained: standard deviation 0.021, confidence interval 5.05±0.05 μg Mn. The method has been applied for the determination of manganese in pharmacological preparations (Biovital, Kinder Biovital) and vegetable fertilizers (Hydrovit 100, Florovit).