Micromass Quattro Ultima, User Manual

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Sodium Iodide Solution for Positive Ion Electrospray
Method 1
Prepare a solution of sodium iodide at a concentration of 2 µg/µl (micrograms
per microlitre) in 50:50 propan-2-ol (IPA):water with no additional acid or
buffer.
Add caesium iodide to a concentration of 0.05 µg/µl.
The purpose of the caesium iodide is to obtain a peak at
z
133 (Cs
+
) to fill the
gap in the calibration file between
z
23 (Na
+
) and the first cluster at
z
173,
which would lead to poor mass calibration in this mass range.
Do not add more CsI than suggested as this may result in a more complex
spectrum due to the formation of NaCsI clusters.
Use reference file NAICS.REF.
Method 2
Prepare a solution of sodium iodide at a concentration of 2 µg/µl (micrograms
per microlitre) in 50:50 propan-2-ol (IPA):water with no additional acid or
buffer.
Add rubidium iodide to a concentration of 0.05 µg/µl.
The purpose of the rubidium iodide is to obtain a peak at
z
85 (
85
Rb
+
) with an
intensity of about 10% of the base peak at
z
173. Rubidium iodide has the
advantage that no rubidium clusters are formed which may complicate the
spectrum. Note that rubidium has two isotopes (
85
Rb and
87
Rb) in the ratio
2.59:1, giving peaks at
z
85 and 87.
Use reference file NAIRB.REF.
Sodium Iodide Solution for Negative Ion Electrospray
Either of the above solutions is suitable for calibration in negative ion mode. In both
cases the first negative reference peak appears at
m
127 (I
-
) and the remaining peaks
are due to NaI clusters.
Use reference file NAINEG.REF.
Reference Information
Page 221
Quattro Ultima
User's Guide