Validation of Ninhydrin Quantitative Method for Cephalexin Generic Tablets

The Medicinal Plant of Corrientes, Argentina, elaborates, distributes and provides free 500 mg cephalexin tablets in hospitals and health care centers. HPLC-UV is the reference method to quantify this antibiotic. The spectrophotometric ninhydrin method was applied for cephalexin quantification and analytical parameters for its validation were determined. The linearity of this method was in the range 0.04-0.20 mg/mL, responding to y = 2.2338x + 0.0007, with R2 = 0.9995. The RSD% found was 0.41, indicating a good repeatability of the analytical procedure. Exactitude in recovery experience was 98.50-101.33%. Comparison using t-tests and F-test indicates that there are no significant differences between results using both methods, with a confidence level of 95%. Specificity and intermediate precision assays were satisfactory. These parameters complete the validation of ninhydrin method, according to requirements of both United States and Argentinean Pharmacopoeia, for its application on cephalexin quality control in generic tablets.