Hplc Program Official

Adjusted time = Original time × (Dwell_new + Gradient_volume) / (Dwell_old + Gradient_volume) Template A: Fast Reversed-Phase Gradient for Small Molecules System: Agilent 1260, C18 3.5 µm, 100 x 4.6 mm

| Symptom | Likely Program Error | Fix | |---------|----------------------|------| | | Insufficient re-equilibration time after gradient | Increase re-equilibration from 5 to 10 minutes | | Pressure spikes at injection | Gradient program changes composition too fast for viscous solvents | Increase gradient time or reduce flow rate during the ramp | | Ghost peaks (blanks show peaks) | No wash step programmed before next injection | Add a 100% organic wash for 3 minutes after each run | | Peaks are split | Injection volume too large relative to starting solvent strength | Reduce injection volume or program a weak needle wash | | No peaks at all | Wavelength set incorrectly or lamp turn-on not programmed | Check detector program; ensure lamp is set to "On" before injection | A Critical Note on Gradient Delay Volume (Dwell Volume) The HPLC program's gradient table assumes mixing happens instantly. In reality, the pump-to-column volume (dwell volume) delays the gradient. For example, a 5-minute gradient on an old system (dwell volume 2 mL) will differ from a new UHPLC (dwell 0.2 mL). Transferring an HPLC program between instruments requires adjusting gradient times using the formula: hplc program

| Time (min) | Flow (mL/min) | %A (Water) | %B (Acetonitrile) | Curve Type | |------------|---------------|-------------|--------------------|-------------| | 0.00 | 1.00 | 95 | 5 | Initial | | 10.00 | 1.00 | 5 | 95 | Linear (6) | | 12.00 | 1.00 | 95 | 95 | Step | | 15.00 | 1.00 | 95 | 5 | Linear (6) | Adjusted time = Original time × (Dwell_new +