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Assessment of the Levels of Phosphate in Detergents Samples

V. E. Agbazue, N. R. Ekere and Y. Shaibu

The concentration of phosphate in some commercial detergents commonly used in homes, laundry services, schools and offices in Kano Metropolis have been determined. The analyses were carried out on both local and foreign detergents using a spectrophotometric method. The method was based on the formation of phosphomolybdate with added molybdate ion followed by its reduction with sodium sulphide in aqueous tetraoxosulphate (VI) acid medium. The system obeys Lambert-Beer’s law at 715 nm in the concentration range 0.30-12.24 mg dm-3 and the data were computed using percentage and t-test. The values obtained for local detergent brand samples were: Bn (0.041%), Om (0.066%), Gn (0.013%), Bb (0.046%), Br (0.046%), Kl (0.035%), Bp (0.053%), Ep (0.010%), Zp (0.025%), Jb (0.014%), and Ar (0.042%) while those of the foreign detergents were Ps (0.005%), Td (0.042%), Lk (0.027%), Ta (0.022%), Dm (0.007%), Bg (0.005%), Bs (0.026%), Kn (0.031%), and Lb (0.006%). The internationally accepted level of phosphate in detergents is 0.5%. Thus, the concentration of these detergent samples fall within the set limit. This study has revealed that continuous use of these products could result in an increase in the phosphate levels in laundry discharges into soil, ponds, lakes and rivers. Excessive amount of phosphate has long been implicated in the eutrophication of surface water bodies, as such, to promote lake/river recovery and improve trophic status. It is imperative that phosphate loads in surface waters are reduced.