Hplc Flow Rate Calculator

HPLC Method Scaling & Flow Rate Calculator

Current Column (Reference)

New Column (Target)

Recommended Flow Rate:

function calculateHPLC() { var d1 = parseFloat(document.getElementById('origID').value); var f1 = parseFloat(document.getElementById('origFlow').value); var p1 = parseFloat(document.getElementById('origParticle').value); var d2 = parseFloat(document.getElementById('newID').value); var p2 = parseFloat(document.getElementById('newParticle').value); if (isNaN(d1) || isNaN(f1) || isNaN(p1) || isNaN(d2) || isNaN(p2) || d1 <= 0 || p1 <= 0 || d2 <= 0 || p2 <= 0) { alert("Please enter valid positive numerical values for all fields."); return; } // HPLC Scaling Formula: F2 = F1 * (dc2/dc1)^2 * (dp1/dp2) // This accounts for geometric scaling and maintaining linear velocity while adjusting for particle efficiency var result = f1 * (Math.pow(d2 / d1, 2)) * (p1 / p2); var scaleRatio = result / f1; document.getElementById('flowOutput').innerHTML = result.toFixed(3) + " mL/min"; document.getElementById('scalingFactor').innerHTML = "Scaling Factor: " + scaleRatio.toFixed(4) + "x original flow"; document.getElementById('hplcResult').style.display = 'block'; }

Understanding HPLC Flow Rate Scaling

When transferring a liquid chromatography method from one column size to another—such as moving from a standard analytical column (4.6 mm ID) to a microbore or UHPLC column (2.1 mm ID)—it is critical to adjust the flow rate to maintain the same linear velocity and chromatographic performance.

The HPLC Scaling Formula

The calculator uses the standard method transfer equation for flow rate:

F₂ = F₁ × (dc₂ / dc₁)² × (dp₁ / dp₂)

Where:

• F₁ & F₂: Flow rates of original and new columns.
• dc₁ & dc₂: Internal diameters of original and new columns.
• dp₁ & dp₂: Particle sizes of original and new columns.

Why Particle Size Matters

Simply scaling by column diameter squared maintains the linear velocity. However, if you are also decreasing the particle size (e.g., from 5 µm to 1.7 µm), you can often increase the flow rate further because smaller particles have shorter diffusion paths, allowing for higher efficiency at higher velocities. This calculator accounts for both diameter and particle size to provide an optimized starting point for your new method.

Example Calculation

If you are moving a method from a 4.6 mm ID column with 5 µm particles running at 1.0 mL/min to a 2.1 mm ID column with 1.7 µm particles:

1. Diameter scaling: (2.1 / 4.6)² ≈ 0.208
2. Particle scaling: (5 / 1.7) ≈ 2.94
3. New Flow Rate: 1.0 × 0.208 × 2.94 ≈ 0.612 mL/min

Practical Tips for HPLC Method Transfer

• Dwell Volume: Remember that smaller columns are more sensitive to system dwell volume. You may need to adjust your gradient start time.
• Backpressure: Reducing particle size significantly increases backpressure. Ensure your HPLC or UHPLC system can handle the calculated flow rate.
• Extra-column Dispersion: Use smaller ID tubing when switching to 2.1 mm ID columns to prevent peak broadening.