Differential-pulse polarographic micro-determination of amino acids via in situ generation of dithiocarbamates

Amino acids underwent in situ derivatization with carbon disulfide in the presence of triethylamine at room temperature to yield the corresponding dithiocarbamate derivatives, which were then determined in aqueous media by differential-pulse polarography. The dithiocarbamate derivative of an amino acid usually showed a characteristic cathodic peak in the range between -0.51 and -0.61 V (versus Ag-;AgCl). Calibration graphs obtained by plotting the measured polarographic peak current of the dithiocarbamate derivative versus the concentration of the amino acid undergoing derivatization were rectilinear over the range 1.6-20 μmol l^-1. For the micro-determination of amino acids, the method was found to be precise, and the detection limit was calculated to be 1 μg.