The FIA is equipped with a 60-position rack, an autosampler with sample volume of 200 lL, a 10 mm path length flow
cell and a colorimetric detector, D, having UV filter of 520 nm. The teflon tubes R1, R2 and R3 of 1.07 mm i.d. were used for the carrier water, buffer and reagent flow respectively while teflon tubes used for the manifold connections, the delay coil, DC (70 cm), and the reaction coil, RC (70 cm) were of 0.8 mm i.d. The details on the instrument and methodology used are outlined in our previous communication