How To Achieve High Throughput - Agilent Technologies Agilent 1260 Infinity System User's Manual

3
Optimization of the Agilent 1260 Infinity Binary LC
How to Achieve Shorter Cycle Times
Carry- over is the percentage of compound that remains in the parts of the
instrument that come into contact with the sample, and is not flushed
onto the column for analysis. It also means that this percentage is lost for
quantitative measurement; it is discriminated. The carry- over can be
measured by injecting pure solvent after the sample run is finished.
Discrimination and carry- over can become even more important if the
analyte compounds are non- polar and the start of the gradient contains a
high percentage of water. In the worst case, the non- polar compound
precipitates at the surface of contact. Small plugs of, for example,
dimethylsulfoxide before and after the sample plug can help to minimize
this problem.
For overlapped injection or automated delay volume reduction, the time
before the injection valve is switched to the bypass mode should be
increased using the flush out factor to 20. This extends the time during
which the autosampler delay volume is flushed with mobile phase.

How to Achieve High Throughput

The injection can be optimized for speed remembering that drawing the
sample too fast can reduce the reproducibility. Marginal gains are to be
made here as the sample volumes used tend towards the smaller end of
the range in any case. A significant portion of the injection time is the
time taken with the needle movements to and from the vial and into the
flush port. These manipulations can be performed while the previous
separation is running. This is known as "overlapped injection" and it can
be easily turned on from the autosampler setup screen in the control
software. The autosampler can be told to switch the flow through the
autosampler to bypass after the injection has been made and then after,
for example, 3 minutes into a 4 minutes run to start the process of
aspirating the next sample and preparing for injection. This can typically
save 0.5 to 1 minute per injection.
50 1260 Infinity Binary LC - System User Guide