Chemometric optimization and flow injection method for the determination of norfloxacin in drug formulations

A flow injection spectrophotometric method for the determination of the antibiotic norfloxacin in drug formulations in the range 50-450 ppm was developed. Iron(III) was employed to produce a coloured complex absorbing at 430 nm in sulfuric acid medium. A factorial design program was utilized to establish the highly interacting factors that must be optimized. Optimization was carried out by the super modified simplex method. The optimum conditions were 0.043 mol dm^-3 sulfuric acid, 0.0271 mol dm^-3 iron(III), flow rate 5.33 cm³ min^-1, sample size 210 mm³ and coil length 45 cm. A sampling frequency of 140 h^-1 was attained.