Chemical Assay of Thiamphenicol and Chloramphenicol

Spectrophotometric and colorimetric methods for the assay of thiamphenicol (TP) and their application to that of chloramphenicol (CP) are described.The spectrophotometric method is based upon the reaction of TP with alkali to produce hydrolyzed TP, D-threo-2-amino-3-p-methylsulfonylphenyl-1, 3-propanediol, which then converted to p-methylsulfonylbenzaldehyde by periodate oxidation.The other is a colorimetric determination of the aldehyde with APHS reagent (diethanolamine salt of azobenzenephenylhydrazinesulfonic acid). The new reagent, in comparison to the free acid, has the advantages in the stability on storage both in crystalline and solution state and in the solubility in some solvents.