Low Mass Irm Stock Solution: 1000 Μg/Ml Methyl Stearate In Acn; Irm Working Solution: 100 Μg/Ml Methyl Stearate And 2% (V/V) Hp-1221 In Acn; Use Of The Irm Solutions - Agilent Technologies G1982-6700 Upgrade Installation Manual

70) is applied. While the use of FC-70 is optional, and signals from the IRM compounds will be
obtained without its use, the response is more uniform and lasts longer when it is used. Note
that ACN and FC-70 are immiscible and so should not be mixed together before applying them
to the wick. (However, they may be applied sequentially to the wick.) The amounts given
below are intended as a guideline but may need adjustment for your instrument or need.
Low Mass IRM stock solution: 1000 µg/ml methyl stearate in ACN
Use reagent grade ACN or higher purity to minimize the presence of unwanted background ions
due to contaminants. Weigh out a suitable amount of G1982-85003 methyl stearate, e.g., 10
mg, into a container, and add 10 mL of ACN to make a 1000 µg/mL of methyl stearate solution.
Shake to dissolve. Refrigerate this stock solution if it is desired to keep it for more than a few
days.
IRM Working Solution: 100 µg/ml methyl stearate and 2% (v/v) HP-1221 in ACN
Add 900 µL ACN to a vial. Add 100 µL low mass IRM stock solution, then 20 µL G1982-85001
HP-1221. Vortex to mix. This working solution must be refrigerated between uses.

Use of the IRM Solutions

The amount of solution to apply or its concentration may need adjustment to suit your needs.
These compounds are designed to persist in the ionization region and are difficult to remove
completely. Therefore, for the first few applications, it is advisable to apply smaller amounts
until the response of your system under your analysis conditions is known. In typical use, 200
µL of the IRM working solution is applied and allowed to evaporate; then 200 µL of FC-70 is
applied. The wick holds approximately 250—300 µL of solution before saturation occurs.
• Using the Acquisition software, set the instrument in Standby mode.
• Eject any Chip from the Chip cube, open the Chip cube cover, and flip out the stages
assembly.
• Briefly vortex the IRM working solution to assure homogeneity.
• Load a pipetter with the desired amount of IRM working solution (e.g., 200 µL).
• Insert the pipette tip into the IRM port on the top plate. It is located closest to the
HPLC Chip Cube and very slowly dispense the IRM solution into the wick. Avoid filling
the port too quickly or the IRM solution will spread across the top plate. See the figure
below for an example.
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