The aim of this study was to control the content of some commercial products containing amino acid (Arginine) available in the local market in addition to other products containing creatine and protein. Three methods were used for quantitative determ
ination of amino acids Kjeldahl method depending on the total content of nitrogen, assay by the visible radiation using Spectrophotometer after ninhydrin derivatization and high performance liquid chromatography with pre-column O-phtadelaldehyde derivatization using fluorescence detector. There were no significant differences in the results obtained by the three used methods. The results revealed that dietary supplements containing creatine and protein were conform to the European pharmacopoeia specifications, regarding products containing arginine used as medication and locally manufactured, they were conform to pharmacopoeia specifications while the illegal dietary supplement containing arginine were not conform.
