Development and validation of an HPLC-DAD analytical method for quantitative and simultaneous determination of cefoperazone and prednisolone in intramammary ointment

Cefoperazone (CPZ) is a third-generation cephalosporin used to treat bovine mastitis. The association with steroidal anti-inflammatory drugs, such as prednisolone (PRED), provides an improvement in the animal's clinical response, which justifies its use. An analytical method capable of simultaneously determining the association between CPZ and PRED by High Performance Liquid Chromatography coupled with a Diode Array Detector (HPLC-DAD) was developed. The method was applied in intramammary ointments, showing linearity, for CPZ, from 0.25 to 25 μg mL-1 (r=0.9999); and, for PRED, from 0.75 to 30 μg mL-1 (r=0.9997), with low limits of detection and quantification, precision with coefficients of variation less than 2%, in accuracy, presented recovery close to 100% for both drugs, in addition to demonstrating their robustness by the Youden test, which evaluated the effects and concluded that the altered parameters in the test were not sufficient to change the values obtained in the determinations. The test was also applied to the commercial sample for quality control purposes, with extraction efficiency being 69.66% for CPZ and 72.36% for PRED. Thus, the developed and validated method can be safely applied in the analysis of the studied drugs.