Thermo Scientific Vanquish VF-D20 Operating Manual page 97

Vanquish Charged Aerosol Detectors Operating Manual
•
Use the lowest practical concentration of additive, especially those
that typically have higher residue after evaporation, such as
trifluoroacetic acid (TFA) and heptafluorobutyric acid (HFBA).
•
Avoid using non-volatile buffers, such as those based on sulfate and
phosphate.
•
Overview of typical additives and buffers that can be used with the
detector:
Additive/Buffer
Trifluoroacetic acid (TFA)
Formic acid
Ammonium formate
Acetic acid
Ammonium acetate
•
The stability of the mobile phase may decrease over time. Prepare
mobile phases freshly on a daily basis.
•
Select the evaporation temperature to optimize the evaporation of
background residue from the mobile phase. See
page 107.
NOTICE Long-term exposure of the detector to non-volatile mobile
phases, such as inorganic buffers, will damage the detector. Do not
use inorganic buffers.
•
If the detector is inadvertently exposed to a non-volatile mobile
phase, use water of LC/MS-grade or better as mobile phase to
remove the salts from the detector.
pKa Buffer range
0.3 --
3.75 2.8 – 4.8
4.76 3.8 – 5.8
section 6.7.5,
6 • Operation
Recommended
max. concentration
0.1%
0.3%
10 mM
0.05 – 1%
10 mM
Page 97