In the context of sample purification, users often perform fraction collection for analytical of preparative purposes. With fraction collection, compounds separated during the run by the chromatographic process are recovered into individual tubes.
To ensure the correct portion of sample is collected, you need to determine the time taken for a compound to travel from the detector to the fraction collector: the Delay calibration time or Delay time. The delays (time or volume) are calculated and stored into the fraction collector to be used later during runs. During a run, fraction collection starts at the retention time of the peak provided by the detector plus the delay time.
For non-MS detectors (DET=UV, DAD, ELSD) a delay volume is calculated.
For MS detector a delay time is calculated.
When a non-MS detector is used (UV, DAD, ELSD) a delay volume is calculated. It represents the tubing volume between the detector and the fraction collector. You have to perform the delay calibration for a system a single time. Calibration has to be done again only if changes were done on the instrument, for example if the length of tubes has been changed.
A method with a constant flow is used to perform a delay calibration run. However, pump flow gradient is supported when submitting runs using a fraction collection method. The computed delay volume is converted during run into a delay time according to the current pump flow (delay time= delay volume / pump flow).
For more information about the delay volume, see Evaluation tab.
When an MS detector is used (Single Quad), delay volume cannot be easily computed as it depends on the main pump flow, make-up pump flow, split rate, and delay coil. So the Delay Calibration tool computes the delay time. The delay time represents the time taken by a compound to travel from the MS detector to the diverter valve of the Fraction Delay Sensor (FDS is the basic detector located in the fraction collector module).
Delay time is calibrated for a dedicated instrument configuration (no change in tubing) and also for a defined acquisition method (pump flow, make up pump flow, splitter). If modifying either the tubing or the method used to run samples, a new calibration must be done (start a new calibration run).
Pump Flow gradient is not supported.
For more information about the delay time, see Evaluation tab.
To perform a Delay Calibration run, you have to purchase dedicated calibration samples. Those samples contain compounds that can be detected by UV, MS and also by the fraction collector delay sensor.
The Delay Calibration is divided into the following parts:
Start a Delay Calibration run to submit a delay calibration run.
Evaluate the Delay Calibration to compute delays and store them into the fraction collector module.
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