Development of a New HPLC Method for Determination of Papaverine in Presence of Its Photooxidation Products

Abstract

A new HPLC method was developed for determination of papaverine in a papaverine naturally photooxidized solution using a Duet C18/SCX column. The mobile phase used was a mixture of phosphate buffer (pH = 3.80) and acetonitrile in 40:60 ratio. The compounds identified were: papaverinol, papaveraldine, papaverine, and pyrrocolonium ion. Very good resolutions, peak shapes, and asymmetries were obtained. An ion exchange experiment was developed in order to identify and separate the pyrrocolonium ion. This was retained completely by a cation exchange resin in its Na⁺ form, while papaverine, papaverinol, and papaveraldine were retained more or less, due to a retention explained by a combined ion exchange-solvent extraction mechanism. Voltammetric studies showed that natural photooxidation of papaverine occurs in three irreversible steps and yields to stable compounds in solution.

Keywords:

• Cation exchange
• Duet C18/SCX column
• HPLC
• Papaverine
• Voltammetry

Notes

Note: The pK _a value reported in literature for papaverine is 6.40 (Halaka 2001).

No literature data are available for papaverinol and papaveraldine acidity constants.

This paper was submitted as part of a Special Memorial Issue honoring George-Emil Baiulescu.