Optimization of conditions for the colorimetric determination of citrulline,using diacetyl monoxime

A method is described for colorimetric determination of citrulline following deproteinization, depending upon the reaction with diacetyl monoxime in the presence of sulfuric and phosphoric acids. Ferric chloride is included to sensitize the reaction and thiosemicarbazide to improve light stability of the chromogen. The method offers diminished heating time compared with existing procedures, combined with good sensitivity and photostability of the chromonphore.