Separation of related opiate compounds using capillary electrochromatography

Area of Science:

• Analytical Chemistry
• Separation Science

Background:

• Controlled narcotic analgesics possess similar structures and charge-to-mass ratios, posing challenges for traditional separation techniques.
• Effective separation methods are crucial for the analysis and control of these compounds.

Purpose of the Study:

• To compare the efficacy of micellar electrokinetic chromatography (MEKC) and capillary electrochromatography (CEC) for separating six controlled narcotic analgesic compounds.
• To determine the optimal conditions for achieving rapid and high-resolution separation of these analytes.

Main Methods:

• Capillary Zone Electrophoresis (CZE) was initially attempted but failed to resolve the compounds.
• Micellar electrokinetic chromatography (MEKC) was performed using a 50 cm capillary with sodium dodecyl sulfate (SDS) and isopropanol in a borate buffer.
• Capillary electrochromatography (CEC) was conducted using a shorter, wider capillary packed with octadecyl silica (ODS) particles, employing a mobile phase of Tris buffer and acetonitrile with SDS.

Main Results:

• CZE did not achieve satisfactory separation due to similar analyte properties.
• MEKC successfully resolved the compounds in 10 minutes, achieving efficiencies of 40,000-150,000 plates/m.
• CEC significantly outperformed MEKC, yielding complete separation in just 2.5 minutes with efficiencies ranging from 250,000-500,000 plates/m.

Conclusions:

• Capillary electrochromatography offers a highly efficient and rapid method for the separation of structurally related narcotic analgesics.
• CEC is a superior technique compared to MEKC for this specific analytical challenge, providing enhanced resolution and speed.