Validación de un método analítico para la cuantificación de alcaloides totales

Introduction: The validation of analytical methods ensures the reproducibility of data, when it is desired to perform the quantification of a product, using methodologies different from those established in official documents. Objective: Validate an analytical method by UV Vis spectrophotometry for the quantification of total alkaloids. Methods: A galenic preparation containing 0.1% of belladonna extract was used to determine the validation parameters using a UV-visible spectrophotometric method at 435 nm, based on the precipitation of alkaloids by interaction with the Dragendorff's reagent. Specificity used a concentration of 100%, while linearity required samples of 80%, 90%, 100%, 110% and 120%; and, in the case of the range, at 80% and 120%. Precision evaluated repeatability at 80%, 100% and 120%, and intermediate precision required a 100% sample considering inter-analyst, inter-team and inter-day conditions. Finally, in accuracy, concentrations of 80%, 100% and 120%; and, for robustness, a 100% sample was analyzed to determine pH variation and centrifugation speed. Results: The selectivity obtained acceptable values in both the matrix and the elaborated product, the linearity presented correlation and determination coefficients close to 1, and the concentration range was between 40-60 mg/L. Accuracy, precision and robustness had a variability of less than 2%. Conclusions: The UV Vis spectrophotometric method is selective, linear, exact, precise and robust; it is reliable in the determination of precipitable alkaloids.