ASTM D500 Test Methods of Chemical Analysis of Sulfonated and Sulfated Oils
TOTAL AMMONIA
50. Scope
50.1 This test method covers the determination of the total ammonia in a sample of sulfonated or sulfated oil, or both, by boiling a water solution of the sample with excess alkali and determining by titration the loss in alkali after the boiling.
51. Procedure
51.1 The procedure consists of two determinations: namely, (a) the total alkalinity, and (b) the loss in alkalinity after boiling with excess NaOH.
51.1.1 Total Alkalinity - Determine the total alkalinity as described in the determination of organically combined sulfuric anhydride, Test Method A (18.1.1).
51.1.2 Alkalinity After Boiling - Dissolve 10 g of the sample in 100 mL of water in a 500-mL beaker, add 25 mL of 0.5 N NaOH solution, and boil the mixture for 30 min or until all the ammonia is expelled as indicated by moistened red litmus paper. Cool the contents of the beaker, add methyl orange indicator solution (0.1 %), and titrate to an approximate end point. Transfer the mixture to a 250-mL glass-stoppered flask and complete the titration (with the addition of salt and ether) as described in the determination of organically combined sulfuric anhydride, Test Method A (18.1.2).
52. Calculation
52.1 Calculate the total ammonia as follows:
T = A + {[(B x D) - (C x E)]/W}
or
Total ammonia, % = 0.0303 T
where:
T = total ammonia, mg of KOH/g,
A = total alkalinity, mg of KOG/g,
B = millilitres of NaOH solution added,
C = millilitres of H2SO4 required for titration of the sample,
D = strength of NaOH solution, mg of KOH/mL,
E = strength of H2SO4, mg of KOH/mL, and
W = weight of sample, g.
