Abstract

Recently, the use of capillary electrophoresis (CE) methods in pharmaceutical practice has gradually increased. Moreover, measurement uncertainty has been used to guarantee the traceability and the reliability of analytical results obtained. The aim of this work was to develop and validate a CE method for the quantification of caspofungin in lyophilised powder for injection, as well as to study the main sources of uncertainty associated with the method proposed and establish a procedure to estimate uncertainty in routine analysis. The results obtained during the validation procedure were statistically evaluated and demonstrate the specificity, robustness, linearity (r = 0.9999; y= 7.9014x-0.0107, concentration range: 20 to 300 mg/ml), precision (repeatability, RSD: 0.40%; intermediate precision, RSD: 0.54%) and accuracy (recovery range: 95.80 to 100.45%). Without using internal standard correction, almost all uncertainty is associated to repeatability of sample and standard peak areas (more than 90%). On the other hand, using internal standard reduced variability significantly. The results allow us to affirm that EC method is suitable for analysis of caspofungin and it may be applied in routine quality control laboratories. In addition, this study confirmed that the equations proposed in the paper may be used for the measurement of uncertainty estimation in routine analysis.

Key words: Caspofungin, capillary electrophoresis, measurement uncertainty.