Abstract
An ion-exchange chromatographic technique for the separation of small amounts of monoguanylmelamine in acetoguanamine by means of a stepwise elution from a 0.8 φ X 20 cm column of a strong-acid cation exchange resin, Dowex 50 WX4, in the sodium form is studied. As the eluant, Sφrensen's buffer solution consisting of glycine, sodium hydroxide and sodium chloride is used. An aqueous solution containing 100 mg of the sample is passed through the column. At first, acetoguanamine and its impurities are eluted with pH 9.9 buffer solution. The elution is continued until the absorption of the effluent at 255 nm is not appear. About 250 ml of the eluant is necessary for this. Then, monoguanylmelamine is eluted with pH 11.1-41.5 buffer solution as shown in Fig.3.150-250 ml of the effluent containing monoguanylmelamine is taken and adjusted to a certain volume by adding the buffer solution. The absorbance of the solution is measured at 255 nm. By this method, monoguanylmelamine in acetoguanamine can be determined down to 0.05%. This method is not interfered by the presence of diguanylmelamine, melamine, acetoguanamide, acetoguanide, cyanomelamine, ammeline and dicyandiamine which are present as impurities in the sample.
