Chemically modified carbon paste ion-selective electrodes for determination of atorvastatin calcium in pharmaceutical preparations

A simple, rapid and sensitive method for the determination of atorvastatin calcium in pharmaceutical preparations using two modified carbon paste electrodes was developed. One electrode (sensor A) is based on ion-pair of atorvastatin with 5,6-diaminouracil hydrochloride (ATS-DAUH) and the other (sensor B) is based on atorvastatin with picric acid (ATS-PC). Among three different solvent mediators tested, dioctylphthalate (DOPH) exhibited a proper behavior including Nernstian slopes of the calibration curve at 58.76 ± 0.8 and 57.48±1 mV per decade for sensors A and B. The response times were 10 and 12 s, detection limits 1.3 × 10⁻⁶ and 2.2 × 10⁻⁶ M; the concentration range 2.5 × 10⁻⁶-7.9 × 10⁻² M and 3.0 × 10⁻⁶ to 7.9 × 10⁻² M respectively. The present electrodes show good discrimination of atorvastatin calcium from several inorganic, organic ions, sugars and some common excipients. The sensors were applied for the determination of atorvastatin calcium in pharmaceutical preparations using standard addition and the calibration curve methods. The results obtained were satisfactory with excellent percentage recovery comparable and sometimes better than those obtained by other routine methods for the assay. The proposed potentiometric methods offer the advantages of simplicity, accuracy, automation feasibility and applicability to turbid and colored sample solutions.