Combi Flash 7650 Series Manual de usuario descargar pdf (Pagina 53)

Section 2 Preparation

2-33

Note

The System Verification procedure (section 2.15) requires a Linear

gradient method.

Enable Run Length Extension – When enabled, this option

automatically extends the run if a peak is eluting at the end of

the maximum %B gradient. This ensures that a late-eluting

peak fully comes off the column and is collected.

An automatic run extension is a five-minute isocratic hold

added to the end of the run’s maximum %B gradient profile.

During the extension, the system continues to pump the

maximum %B solvent mixture. Should the system still detect

a peak after an extension, the system will add another, up to a

maximum of three extensions.

Occasionally, compounds might come off the column once the

%B returns to the minimum value at the end of a run. If the

Run Length Extension is enabled, it will automatically extend

the run one time to clear the column and plumbing of any

remaining material.

Figure 2-21 Automatic Run Extension Examples

Figure 2-21 illustrates the possible run extensions. The

original method was programmed to rise to the maximum %B

over seven minutes, hold for two minutes and return to the

minimum %B for a final minute. At nine minutes, a peak was

eluting. PeakTrak extended the run, holding the %B at the

maximum level for another five minutes. This also occurred at

fourteen and nineteen minutes, resulting in the second and

0 5 10 15 20 25

Original method

Extension 1

Extension 2

Extension 3

Final Extension

Minutes

1 2 ... 48 49 50 51 52 53 54 55 56 57 58 ... 158 159

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Combi Flash 7650 Series Manual de usuario Pagina 53