the method is based on ion-pair extraction of the cation with perchlorate , a re-extraction according to ion-pair principles with tetrapentylammonium as the counter ion , hydrolysis to cyclohexylphenylglycolic acid , derivatization of this acid to its pentafluorobenzyl ester and determination of the ester by gas chromatography and electron-capture detection .
C0007447
cation
C0022023
ion