Selective GLC determination of epinephrine, isoproterenol, and phenylephrine in pharmaceutical dosage forms

A simple, specific GLC analytical procedure for the quantitation of epinephrine, isoproterenol, and phenylephrine in commercial tablets, powders, inhalation solutions, ophthalmic and nasal drops, and injectable preparations is presented. Samples are taken to dryness where required, the dried residue is reacted with an appropriate trimethylsilylating reagent, and the derivatives are eluted from a methyl silicone column using temperature programming. Quantitation of the flame-ionization detector signal is achieved relative to the dibenzyl succinate internal standard by an electric integrator. The results obtained by applying the method to the analysis of each of the three drugs in several simulated decomposed mixtures were in good agreement with theoretical values, even at impurity levels of up to 80% by weight. When applied to commercial formulations, the procedure was feasible for tablets, powders, and solutions at drug concentrations of 0.2% or greater. The commonly incorporated buffering and antioxidant excipients did not interfere.