Standardizing chemical peel solution formulations to avoid mishaps. Great fluctuations in actual concentrations of trichloroacetic acid.

Background: Chemical peeling using trichloroacetic acid (TCA) is a popular and long utilized procedure in dermatology and cosmetic surgery.
Objective: To determine the actual concentration of TCA in four disparate methods of preparation of solutions, expressed in the standard pharmaceutical method of weight to volume (wt/vol).
Methods: Method I was wt/vol, method II was weight to weight (wt/wt), method III was grams of TCA added to 100 cc water, and method IV was the usage of saturated TCA, and calling it 100%, then making appropriate dilutions. The amounts of TCA in each solution for methods II, III, and IV were converted, by calculation, to the wt/vol method.
Results: The relative concentrations of TCA, ranked by the wt/vol pharmaceutical standard, showed that from strongest to weakest: method IV > method II > method I > method III.
Conclusions: Tremendous variations were found in the relative concentrations of TCA in these solutions. To avoid mishaps and complications, the wt/vol method should be used.