J. Saurina et S. Hernandezcassou, SIMULTANEOUS DETERMINATION OF SEVERAL AMINO-ACIDS WITH MULTIVARIATE CALIBRATION METHODS BY USING A CONTINUOUS-FLOW SYSTEM, Analyst, 120(2), 1995, pp. 305-312
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.