| 摘要 |
PURPOSE:To improve the storage stability of aqueous solution of DTPA.Fe salt by adjusting the pH of aq. soln. of diethylenetriamine penta acetate to 4-7 and retarding the formation of hydroxide of divalent Fe in the aq. soln. CONSTITUTION:The pH of aq. soln. of DTPA.Fe salt is adjusted to 5-7 and the formation of hydroxide of divalent Fe in this aq.soln. is retarded. If the pH of the aq. soln. is adjusted to 4-7, more pref. to 4.5-6.5, the hydroxide of divalent Fe is hardly precipitated even after storage for a long time, thus the soln. becomes suitable for a photographic chemical without causing any trouble. By the way, if the pH exceeds 7, the velocity for forming the precipitate of the hydroxide of divalent Fe is too fast, remarkable increase of precipitate of divalent during storage for a short time is caused and appropriate effect for photographic chemical is forfeitured. on the other hand, if the pH is <4, aq. soln. of appropriate concn. is ot obtd. because the solubility of DTPA.Fe salt is too small. By this constitution, DTPA.Fe salt can be obtd. in the form of stable aq. soln. |
