LC Simulator: Meaning of “Flow Rate” fields and how t₀ is calculated

Description
In LC Simulator there are two separate flow rate fields:

• “At a Flow Rate of” (in Column Parameters): flow rate used when the Observed t₀ and Observed Pressure values were measured.
• “Constant Flow Rate” (in Elution Data): flow rate actually used in the current experiment.

Both fields are independent and are used together to compute the dead time (t₀) for a specific experiment.

Solution

1. In the Column Parameters, enter:
   • Observed t₀: the measured dead time at the conditions of your reference experiment.
   • At a Flow Rate of: the flow rate used when you measured Observed t₀ and Observed Pressure.
2. In the Elution Data (method conditions), enter:
   • Constant Flow Rate: the flow rate actually used for the modeled/optimized experiment.
3. LC Simulator uses the following relationship to calculate t₀ for the current experiment:
   • t₀(current) = Observed t₀ × (At a Flow Rate of) / (Constant Flow Rate)
4. If only one flow rate value is known:
   • Enter the same value in both fields.
   • In this case, t₀(current) equals the Observed t₀.
5. Verify the result by:
   • Checking that calculated t₀ values are reasonable for your column dimensions and mobile phase.
   • Adjusting flow rate values if you detect obvious inconsistencies.