WATERS CORPORATION 2424, Operator'S Manual, Page: 164 / 196

6-6 Optimizing Detection and Preparing Solvents
Properties of volatile mobile phase modifiers
The following table lists the properties for volatile mobile phase modifiers.
Water 17.54 at 20 °C 100.0
o -xylene 6 at 20 °C 144.41 17
Properties of volatile mobile phase modifiers
pKa pKb pH range
Boiling
Point (°C)
Acids
Acetic Acid
4.75 9.25 116.00
Carbonic Acid 6.37 7.63
Formic Acid 3.75 10.25 100.70
Trifuoroacetic
Acid
0.30 13.70 71.80
Bases
Ammonia
9.25 4.75 -33.35
Ethylamine 10.81 3.19 16.60
Methylamine 10.66 3.34 -6.30
Triethylamine 11.01 2.99 89.30
Buffers
Ammonium
Acetate
3.8 to 5.8
Ammonium
Carbonate
5.5 to 7.5
and 9.3 to
11.3
Ammonium
Formate
3.0 to 5.0
Properties of common solvents (Continued)
Solvent
Vapor Pressure
mm Hg (Torr) Boiling
Point (°C) Flash
Point (°C)