The original pharmacopoeia monograph method for the synthesis residue camphor-10-sulfonic acid in voriconazole, stipulates the use of a column with a strongly basic anion-exchange resin and a basic hydroxide eluent containing 25% methanol. Diduco have developed a new alternative method for the determination of voriconazole impurity E using a more straightforward carbonate-based eluent and a much more hydrophilic column, thus requiring only 5% organic solvent. This new quality control method was developed according to the ICH guidelines and meets the system suitability criteria of the original method.