OBJECTIVE or GOAL
- Gradient Start allows a user to change the time the gradient starts with respect to the injection adding or decreasing the gradient delay.
- Developed for method transfer to match results between systems with differing gradient delay volumes.
- Empower Instrument Method
- ACQUITY UPLC H-Class Quaternary Solvent Manager (QSM)
- ACQUITY Arc QSM-R
- ACQUITY UPLC Binary Solvent Manager (BSM)
- ACQUITY UPLC I-Class BSM
Programming: Set by time or volume
- Compare Waters system peak retention time result versus system "X"
- Choose a mid point peak of the Waters result. Record the time of that peak.
- Compare the retention time difference of that same mid point peak with System "X". Record the difference in time.
- In the Empower Instrument Method for the Waters system, select the Gradient Start (before or after injection).
- "Before injection" to move the peaks to earlier retention times.
- "After injection" to delay the gradient shifting peak elution to a later retention time.
- Set the value by time (recommended).
- Perform a run to match the retention time of the Waters system result with that of system "X" and ensure peak retention is within acceptance criteria.
Modifying the gradient start time (Gradient Smart Start) will not affect the retention time of a peak eluting in the isocratic portion of the chromatogram (systems isocratic hold/volume). Other factors affecting a change in retention time are temperature, column volume and chemistry, mobile phase modifiers/additives, flow rate, etc.