mol l dtpa represents u02dc 12 times the stoichiometric requirement for acid base neutralization the test described in example 2 was repeated under otherwise the same conditions but with a higher dosage of the base solution 40 7 grams of the same 28 wt ammonia solution 11 4 g of nh 3 only the heavier dtpa rich organic phase was formed there was no formation of solids observed the recovered dtpa rich organic phase contained 1 66 mol kg dtpa 40 7 g kg p and 79 9 g kg s indicating the essentially complete removal of the non dtpa organophosphorus compounds the ammonia dosage 11 4 g of nh 3 equivalent to 0 67 moles of nh 3 compared to the 0 034 moles of dtpa in the sample 200 ml of 0 171 mol l dtpa represents u02dc 20 times the stoichiometric requirement for acid base neutralization this example illustrates the importance of base dosage for preventing solids formation as well as achieving the high degree of dtpa separation the test described in example 1 was repeated under otherwise the same conditions but using a field organic solution containing chemically extracted nickel at several gram per liter concentration even with a higher dosage of 50 wt naoh solution a precipitate of nickel hydroxide intermixed with an organic phase was produced effective physical separation of such mixture of.