High-performance liquid chromatography of amino acids and peptides on silica coated with ammonium tungstophosphate : I. Characteristics of the stationary phase

Silica coated with ammonium tungstophosphate is proposed as a stationary phase for high-performance liquid chromatography. The chromatographic characteristics of columns packed with this material were investigated. The retention of compounds containing an NH + 4 group, such as amino acids and peptides, is determined by an ion-exchange mechanism; the silica coated with ammonium tungstophosphate behaves as a reversed phase in the case of aliphatic and aromatic organic acids when eluting with aqueous buffer solutions. The new stationary phase shows a high selectivity towards glycine and tyrosine oligomers.