Development and validation of an HPLC method for the quantitation of tromethamine in Iopamidol injection

An HPLC method using a precolumn derivatization with 1-(1-naphthyl)-ethyl i socyanate (NEIC) was developed for the quantitation of tromethamine, an exc ipient in iopamidol injection. In this procedure, both tromethamine and the internal standard react with NEIC. Following this pre-column derivatizatio n, the solution is injected onto an Inertsil ODS reverse phase HPLC column. The peaks corresponding to the two derivatives are separated from each oth er and from the peaks corresponding to iopamidol and its related substances . The validation studies indicate that the method is specific, accurate, pr ecise, and rugged over the concentration range (0.50 - 1.25 mg/mL) investig ated.