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40 Installation and Operation Guide
4 Operation
An Example
Assume we have a method that uses an HP-5MS column (30 m × 250 µm
id × 0.25-µm film thickness) to measure pesticides with an MSD. The initial
oven temperature is 70 °C and is programmed to 280
ο
C. The method is run in
constant pressure mode at 19.44 psig inlet pressure and the carrier gas is
helium. The initial column flow listed by the ChemStation is 2.1 mL/min.
We want to create a new splitter method with the column effluent split 1:3
between the ECD (detector 1) and an MSD (detector 2). We would also like to
preserve the retention times and relative elution order in the new method.
Column flow
Since the column outlet pressure will be much higher in the new method, the
first step is to calculate the new inlet pressure and the resulting column flow.
The Method Translation software (Figure 18) is useful for this. Use the None
mode and check the button to make the hold-up times the same.