High-performance liquid chromatographic analysis of codeine in syrups using ion-pair formation

Area of Science:

• Analytical Chemistry
• Pharmaceutical Analysis

Background:

• Reversed-phase high-performance liquid chromatography (RP-HPLC) is a common technique for analyzing pharmaceutical compounds.
• Opioid alkaloids such as morphine, codeine, and ethylmorphine present challenges in chromatographic separation due to their basic nature.

Purpose of the Study:

• To investigate the chromatographic behavior of morphine, codeine, and ethylmorphine using ion-pair formation.
• To develop a quantitative method for codeine in syrup formulations.

Main Methods:

• Reversed-phase high-performance liquid chromatography (RP-HPLC) was employed.
• Ion-pair formation was utilized with various alkyl sulfonates and sulfates as pairing ions.
• Dioctyl sodium sulfosuccinate was specifically investigated as a pairing ion for codeine analysis.

Main Results:

• Alkyl sulfonates and sulfates significantly increased the retention times of the studied amine drugs.
• A linear relationship was observed between the carbon chain length of the pairing ions and the logarithm of the capacity factors.
• A validated method for codeine quantitation in syrups using dioctyl sodium sulfosuccinate was successfully developed and applied.

Conclusions:

• Ion-pair formation in the mobile phase is an effective mechanism for enhancing the retention of basic drugs in RP-HPLC.
• The developed method provides a reliable means for quantifying codeine in complex pharmaceutical matrices like syrups.