An application of Doehlert matrix optimization on developing of flow injection analysis of neomycin in pharmaceutical samples

This work proposes a Flow Injection Analysis (FIA) system to determine neomycin in pharmaceutical formulation, utilizing ninhydrin as chromogenic reagent, with absorbance signal measured at 570 nm. To check the significant flow parameters, a screening with 2 4 full factorial designs was optimized, and a Doehlert matrix used to obtain the optimum variable values. The method presents two linear responses ranging from 29.8 up to 300 mg L -1 (r 2 =0.9933) and 800.0 up to 2500 mg L -1 (r 2 =0.9926). The Limits of Detection and Quantifications were 8.94 mg L -1 and 29.8 mg L -1 , respectively. The readings frequency was of 33 reading h -1 . The method accuracy was checked through comparison with HPLC method and the results found were similar (t-test, 95% confidence level). The method was applied in pharmaceutical samples with very good performance and the precision (RSD) was always below 8.0%. The reagent and sample consumption was very low, what is in agreement with the green chemistry concept