by John C. Anders, aaiPharma, Inc., Benne F. Parten, Glenn E. Petrie , Robert L. Marlowe , and John E. McEntire Amino acid analysis (AAA) of well-recovered residues offers an easy way to calculate the absorptivity constant for a known protein. The method provides an absolute measure of protein concentration, free from interference from water, excipients, and bound salts. This article demonstrates a qualified method for determining protein content by AAA.