Resistance to Mass Transfer Formula:
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Definition: The resistance to mass transfer (C) represents the contribution to band broadening in chromatography due to the finite rate of mass transfer between the mobile and stationary phases.
Purpose: This calculator helps determine the C term in the Van Deemter equation, which is crucial for understanding and optimizing chromatographic separation efficiency.
The calculator uses the formula:
Where:
Explanation: The formula isolates the C term from the Van Deemter equation by subtracting the A and B/u terms from the plate height H, then dividing by the mobile phase velocity.
Details: Understanding the C term helps chromatographers optimize flow rates and column parameters to minimize band broadening and improve separation efficiency.
Tips: Enter all parameters in their respective units (H in meters, B in m²/s, u in m/s, A in meters). All values must be positive numbers.
Q1: What is the Van Deemter equation?
A: The Van Deemter equation describes the relationship between plate height (H) and mobile phase velocity (u) in chromatography: H = A + B/u + Cu.
Q2: Why is resistance to mass transfer important?
A: It becomes the dominant factor in band broadening at higher flow rates, affecting chromatographic resolution.
Q3: What are typical values for the C term?
A: Values typically range from 0.01 to 0.1 seconds, depending on column properties and analytes.
Q4: How can I reduce resistance to mass transfer?
A: Using smaller stationary phase particles, thinner stationary phase films, or optimizing temperature can help reduce C.
Q5: What's the relationship between C and flow rate?
A: The C term becomes more significant at higher flow rates, as mass transfer limitations increase.