Second-derivative spectrophotometry for the analysis of simvastatin in polymeric nanocapsules

Abstract

Conventional spectrophotometry methods are very susceptible to the presence of interferences in complex mixtures such as nanoparticules, requiring prior treatment or extraction of the analyte, and not always providing an adequate response. Derivative spectrophotometry method is capable to eliminate its interference; it is an alternative method for drugs determination in complex matrices. This work investigated the utility of derivate spectrophotometry in assay of simvastatin in polymeric nanocapsules (SIVNC). Shimadzu^® UV-1650 double-beam spectrophotometer with 1.0 cm quartz cells was used in this study. The second-order deriva­tive spectrum was obtained employing Δλ=20,000 nm and scaling factor=9.0. The determinations were made at 239 nm (²D₂₃₉) by zero-crossing method. ²D₂₃₉ method was validated employing the parameters: specificity, linearity, robustness, precision and accuracy. Results: The specificity test showed there was no interference of constituents commonly found in SIVNC formulation in ²D₂₃₉. The standard curve showed a correlation coefficient of 0.994. The robustness was evaluated by small changes in the conditions of sample analysis and however, no significant changes were observed regarding drug quantitation. The precision was demonstrated by relative standard deviation (RSD) of intra-day (RSD=1.61-3.76) and inter-day studies (RSD=2.32). The recovery test resulted in an average of 100.66%, which confirmed the accuracy of the method. The procedure was simple and rapid; therefore this technique offers an alternative for determination of SIVNC without interferences.