SIMULTANEOUS DETERMINATION OF SEVERAL AMINO-ACIDS WITH MULTIVARIATE CALIBRATION METHODS BY USING A CONTINUOUS-FLOW SYSTEM

An initial approach to the simultaneous determination of several amino acids by using multivariate calibration methods is proposed. The meth od is based on the development of the reaction between amino acids and 1,2-naphthoquinone-4-sulfonate. Spectra of the corresponding derivati ves obtained from a continuous-flow system were used td provide multiv ariate data for the multivariate procedure. Two multivariate calibrati on methods were applied, principal component regression (PCR) and part ial least-squares regression (PLS). In order to compare the resolution capabilities of these multivariate methods, a series of synthetic sol utions containing different concentrations of lysine, proline, phenyla lanine and tryptophan were prepared. The selection of solutions for ca libration and problem sets was performed on the basis of the distribut ion of the amino acid derivatives spectra on the first and second prin cipal components, The effects of the number of working wavelengths, th e number of principal components and the mathematical treatment of dat a (smoothed and derivative spectra) on the predictions were also inves tigated. The method was applied to the analysis of feed samples, where the determination of some particular amino acids such as lysine are o f special interest. The results were in good agreement with those obta ined with the standard amino acid autoanalyser procedure.