Method for inhibiting nitrosamine formation in anion exchange resins

1. A method for inhibiting formation of nitrosamines comprising:

providing an anion exchange resin together with a nitrite salt, wherein the nitrite salt is present in an amount of 100 ng/L; and

applying an antioxidant to the resin by blending the antioxidant with the anion exchange resin to inhibit formation of nitrosamines on the anion exchange resin such that the anion exchange resin comprises no more than 15 ng/L nitrosamines, wherein the applying comprises

providing a solution of the antioxidant in a nonreacting solvent;

blending the solution with the anion exchange resin; and

then draining the solution from the anion exchange resin,

wherein a weight ratio of the antioxidant to the wet anion exchange resin is from 1:5000 to 1:500.

2. The method of claim 1 wherein the antioxidant comprises at least one of erythorbic acid, thiodipropionic acid, potassium metabisulfite, ascorbyl palmitate, sorbic acid, vitamin E (tocopherols),

1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydrodybenzyl)benzene,

octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate,

ascorbic acid and

2,6-di-tertiary-butyl-N,N-dimethylamino-p-cresol

2,6-di-tert-butyl-N,N-dimethylamino-p-cresol.

3. The method of claim 1 further comprising:

disrupting formation of nitronium ions; and

limiting reaction of the nitronium ions with secondary amines.

4. The method of claim 1 , wherein the ion exchange resin has been made using one or more polyunsaturated vinylaromatic monomer and one or more monounsaturated vinylaromatic monomer.

5. The method of claim 4 , wherein the ion exchange resin has been made using monomers comprising: one or more monomer selected from the group consisting of divinylbenzene, trivinylbenzene, divinyltoluene, divinylnaphthalene, divinylxylene, and mixtures thereof and one or more monomer selected from the group consisting of styrene, (C 1 -C 4 )alkyl-substituted styrenes, halo-substituted styrenes, vinylnaphthalene, vinylanthracene, and mixtures thereof.

6. The method of claim 1 , wherein the nitrite salt is either an impurity from a raw amine used in the amination or is trace NO 2 ⊖ from water or salt used in the amination.

7. An anion exchange resin prepared using the method of claim 1 .