Dispersion; Carryover - Waters ACQUITY UPLC M-Class System Manual

• For best performance, configure eluent compositions with at least 3% A
or B. Lesser contributions from either the A or B eluent may result in
decreased retention time reproducibility.
• Monitor the waste level, to ensure that it is never too high.
• When starting the μBSM, ensure solvent flows through pump A and
pump B. Do not specify a 0.0 mL/min flow rate at startup for either
pump.
• Use the Load Ahead function when you want a shorter cycle time.
• If you experience problems with carryover, do not use the Load Ahead or
Loop Offline functions while you troubleshoot.
• Use of the advanced sample introduction features requires extensive
knowledge of the sample.
Warning:
when moving the micro cart or instrument modules or when
adding or changing reagents.

Dispersion

Microscale systems require low dispersion for optimum performance. This is
achieved by using small-particle chromatography.
Small-particle chromatography relies on the use of small, high-efficiency
columns. A typical 75 μm × 250 mm UPLC column has an approximate 1-μL
volume, compared with 40-μL for a typical 4.6 × 150 mm UPLC column. The
smaller column requires a system with low dispersion that reduces dilution
and band broadening, thus maintaining the symmetrical peak shape, height,
and sensitivity produced by the high efficiency column.

Carryover

You observe carryover in chromatographic systems when a previously injected
analyte appears as a peak in the chromatogram of subsequent samples.
Carryover tends to occur when a small amount of analyte remains in the
system after a sample is injected. You can measure carryover by observing
analyte peaks that appear when you run a blank sample immediately after an
analytical sample.
To prevent injury, always remove the solvent bottles
March 10, 2014, 715003588 Rev. A
Dispersion
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