Fast separation of amino acid phenylthiohydantoin derivatives by HPLC on anon-porous stationary phase

A new method is described for the separation of phenylthiohydantoin (PTH) d erivatives of the 20 common amino acids. The analysis requires approximatel y 7 minutes and good resolution is obtained by RP-HPLC on columns packed wi th a non-porous stationary phase (Kovasil-C14; 33 x 4.6 mm). Gradient eluti on was chosen with eluents containing either sodium acetate / acetic acid b uffers (moderately acidic conditions) or a heptafluorobutyric acid modifier (strongly acidic eluent). A slightly different elution order of the PTH-am ino acids was found in the two systems. Low detection limits (in the femtom ol range) were achieved with simple commercial HPLC equipment.