Spectrophotometric determination of manganese(II) and basic polyamino acids with o-sulfophenylfluorone

A spectrophotometric method was established for the determination of manganese(II) {Mn(II)} and Polylysine (PolyL) with o-sulfophenylfluorone (SPF). Beer's law was obeyed in the range of 0.06~3.3 μg for Mn(II) in a basic medium with an apparent molar absorptivity(ε) at 565 nm, the relative standard deviation (RSD) being 1.63×10⁵ L mol^-1 cm^-1 and 1.46 ( (n =5). This method is about 2-70 times more sensitive than the existing spectrophptpmetric methods, and can determine more easily. Also, the method was successfully applied to assays of Mn(II) in real samples. The thermodynamic parameters suggest that the colored complex formed in this reaction system is an association complex between [Mn(II)=SPF] and [TSAC]. Next, Beer's law was obeyed in the range of 1.0~60 μg for PolyL, a basic solution. The ε and RSD are 4.18×10⁶ L mol^-1 cm^-1 (molar weight≒225000) at 565 nm and 1.49 ( (n =5), respectively. This method can determine polymers, not monomers. Furthermore, this method was applied to recovery tests of PolyL in real samples; the results were satisfactory.