Abstract: In this work, we proposed a new method for the simultaneous determination of cinnamic acid, L-phenylalanine and amonium sulfate in solution using combined potentiometric titration and chemometrics. The partial least squares (PLS) algorithm was applied and 25 standard mixtures of the compounds were prepared according to orthogonal experimental design for calibration set. The commonly used leave-one-out cross-validiation method was used to select the optimum number of factors in the PLS model. An independent set of synthetic raw mixtures was employed to evaluate the prediction performance of the resulting models. The results showed that the recovery values ranged from 92.9% to 104.4% for cinnamic acid, 94.9% to 101.5% for L-phenylalanine, and 96.6% to 105.1% for amonium sulfate respectively. The study proves the feasibility of simultaneous spectrometric determination of cinnamic acid, L-phenylalanine and ammonium salts in raw mixtures without preliminary separation steps.

Key words: L-phenylalanine, partial least squares (PLS), chemometrics, simultaneous determination