Vikash Kumar, Kamal Dua, Sushila Rathee and Permender Rathee
A finest quantitative responsive with reproducible best method was developed using designed array (Taguchi) and Quadratic design methodology (RSM) chromomeric spectrophotometric estimation of bulk as well as pharmaceutical (Tizanidine HCl). Initially (Taguchi), orthogonal array design was applied to find significant variables as well as optimum (better) levels. By response surface (central composite; quadratic) methodology were used to ascertain optimum to optimized ?Better to Best? and studied values of variables (independent significant; X1=PDAB=chromogenic reagent; FeCl3=X2=ferric ion at optimum levels with drug constant=X3) responses (dependent Y1=absorbance) models at positive and negative (+1/-1 optimum spaces) levels. More-more, designed independent factorial levels ?better to best? surface models (3D) and its polynomial (2nd order) equation was predicted the finest level which further can be considered as best chromomeric estimation method. The models analysis of experimental variables and their level showed and followed good Beer?s (5-50 ?g/ml) correlation at optimized significant independent best (finest) level variables and in-addition validated using pharmaceutical guidelines (ICH; international conference on harmonization) for human use.