Simultaneous kinetic determination of phenols by use of the kalman filter

A multicomponent analysis method based on the Kalman filter algorithm is proposed for the determination of phenolic compounds. The method relies on the oxidative coupling of phenols (phenol, 2-chlorophenol and 3-chlorophenol) to N,N-diethyl-p-phenylenediamine in the presence of hexacyanoferrate(III), the reaction being monitored via changes in the absorbance at 660 nm of the dye formed. Phenols can be determined individually over the concentration range 1.25-25 muM with a relative standard deviation of ca 0.6-0.8%. Differences in the kinetic behaviour of the three species were exploited by using the linear Kalman filter to resolve mixtures of the phenols at the muM level in a widely variable concentration ratios with errors less than 10%.