Binary heteropolytungstate anion systems of SiW11O398- and SiW12O404-, PW12O403- and SiW12O404-, and PW12O403- and SiW11Fe(H2O)O395- were separated by reversed-phase liquid chromatog. with CH3OH-phosphate buffer as eluent. The anions with lower charge no. have longer retention. As the pH value of the buffer or the concentration of CH3OH in the eluent increases, the retention of SiW12O404- decreases, whereas SiW11O398- remains unchanged under all the conditions investigated. Good chromatog. peaks were obtained when the pH value of the buffer was between 3.76 and 4.66.

Key words: HETEROPOLYACID, METHANOL, HIGH SPEED LIQUID CHROMATOGRAPHY, CHROMATOGRAPHY, REVERSED PHASE CHROMATOGRAPHY, PHORSPHORIC ACID, POTASSIUM COMPOUNDS, SILICATE P, PHOSPHATE P, TUNGSTATE P