Waters ACQUITY UPLC M-Class System Manual page 73

Suspected cause
Void volume or bad consumables
4.3.2.15 Loss of sensitivity
Suspected cause
Wrong injection volume; less sample loaded on
a column results in a lower response.
Needle wash solvent composition; weak wash
too high in organic solvent.
The programmed gradient table is incorrect.
The programmed flow rate is too low.
Incorrect mobile phase due to one or more of
the following:
• Percentage of organic use is incorrect
• Wrong solvent used
• Programming error
• Wrong pH
• Mobile phase contaminated
Column temperature is programmed too low.
Needle depth is programmed too high or too
low.
Incorrect method selected in the sample list.
Needle and sample loop volume are not
calibrated or are configured incorrectly.
Plate configuration is incorrect, so needle does
not reach the sample.
Possible solution
Perform a systematic replacement of
consumables beginning with the analytical
column.
Possible solution
Change to correct injection volume.
Make fresh weak wash solvent.
Correct the gradient table.
Program the correct flow rate, ensuring that it
is appropriate for the column ID.
Make fresh mobile phase and ensure that the
solvent used and gradient programmed is
appropriate for the method.
Set the correct column temperature.
Check, and if necessary, select the correct
method for the analysis.
Verify the needle and sample loop
characterization and, if necessary, re-
characterize the volumes.
Set the correct plate configuration.
November 26, 2019, 715003588 Revision C
Page 73
• Verify the needle depth setting.
• Ensure that the correct sample volume is
used.
• Ensure that the correct vial or well plate
type are used.