Mobile Phase Tips; Degas Solvents And Buffers; Check Uv And Visible Absorbance Of Solvents - Gilson 155 User Manual

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Operation

Mobile Phase Tips

Degas Solvents and Buffers

Always use degassed, HPLC-grade solvents
(including water) and buffers for your mobile phase.
If the back pressure on the flow cell is sufficiently
low, gas bubbles may still appear, even when using
degassed solvents. You can avoid this by using a
back pressure regulator. The detector accessory
packages for an analytical, microbore, preparative,
and capillary flow cells include a back pressure
regulator. Refer to page 2-13 for back pressure
regulator installation instructions.
Check UV and Visible Absorbance of
Solvents
Remember to use only HPLC-grade solvents for
your mobile phase. Impure solvents can absorb
significant quantities of UV or visible light even
when the cutoff may be below the monitoring
wavelength. This can result in an inability to
accurately set the baseline to zero.
Manufacturer's specifications list the UV and
visible cutoff for a solvent. This is the wavelength
below which a solvent should not be used for UV
or visible detection. The cutoff is the wavelength at
which the solvent is 90% opaque (absorbance 3, 1.0
AUFS). Interference can still occur above the rated
limit, particularly when the solvent composition
changes during a run. This frequently appears as a
gradual baseline shift.
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