Simultaneous separation of the stereoisomers of 1-amino-2-hydroxy and 2-amino-1-hydroxypropane phosphonic acids by stereoselective capillary electrophoresis employing a quinine carbamate type chiral selector

A stereoselective nonaqueous capillary electrophoresis (CE) method utilizin g O-(tertbutylcarbamoyl) quinine as chiral ion-pair agent and additive to t he non aqueous background electrolyte was evaluated for the simultaneous se paration of the enantiomers and diastereomers of 1-amino-2-hydroxypropane p hosphonic acid besides the corresponding beta -aminophosphonic acid analogs , the stereoisomers of 2-amino-1-hydroxypropane phosphonic acid, in a singl e run. The separations have been carried out using the partial filling tech nique to avoid strong background signal from the quinine selector. It conve niently allowed the baseline separation of all eight components of interest (alpha- as well as beta -aminophosphonic acids) as N-2,4-dinitrophenyl der ivatives in a single run. Moreover, the absolute configurations of all eigh t peaks were identified. Compared to the quinine carbamate selector, the co rresponding 'pseudo-enantiomeric' O-(tertbutylcarbamoyl) quinidine selector exhibited reserved elution order and nearly identical resolutions. The pro posed CE method turned out to be advantageous over stereoselective high-per formance liquid chromatography (HPLC) with a quinine carbamate type station ary phase, which showed high enantioselectivity, but failed to simultaneous ly separate all eight components.