Protein quality is determined by the type and concentration of the essential
amino acids and by their bioavailability. Hence, the content of dietary
essential amino acids from a protein or mixture of proteins is a factor which
determines the feeding quality of the protein. The purpose of the study was
to evaluate the quality of the protein from a high protein raw ingredient
(corn gluten) using a chromatographic method (HPLC) under optimized
experimental conditions. In this study, we used pre-column derivatization,
separation by high-performance liquid chromatography (HPLC) and UV detection.
The optimized method was used to determine the amino acids from high-protein
raw ingredients commonly used in animal feeding (corn gluten, 61%CP). A set
of 6 amino acids analyses has been performed in 6 different days, each sample
being prepared in double. For characterization of data strings we used
quality parameters: average, standard deviation, standard error, confidence
level, precision, accuracy. For verifying the Gaussian shape of the strings
we used the Kernel Density. For identifying and rejecting the outliers from
the data strings we used the Q test. The very low values of the accuracy for
several amino acids (glutamic acid, threonine, alanine, valine,
phenylalanine, isoleucine, leucine) determined us to introduce the dilution
stage (1:2) for the hydrolysed samples. The method can be considered as
repeatable (precision in different days) and accurate (evaluation by tracing
yields) for all the determined amino acids.