Waters ACQUITY UPLC M-Class System Manual page 105

• Replace bottle sinkers at least monthly.
• Condition following neutral or basic mobile phase operation.
D.2.4.1 Using clean water and glassware
Using clean water and glassware is essential to keeping microbial levels sufficiently low.
Use MS-grade water filtered to 0.1 μm or smaller. If you use water from an ultra purification
system, follow all the manufacturer's guidelines regarding use, maintenance, service, cleaning,
and parts replacement. If you use bottled water, ensure that the container was not left open or
uncovered for an extended period.
If possible, autoclave glassware before use. Otherwise, rinse glassware with ultra-pure water
before mixing the mobile phase. Always rinse any surfaces that could contact the mobile phase.
D.2.4.2 Adding organic solvent
If the application allows, add up to 20% of an organic solvent, such as acetonitrile or methanol, to
neutral or basic mobile phases to help control microbial growth. Be aware that adding organic
solvent is not a substitute for any of the other strategies to combat bacterial growth (see
Operation with neutral or basic pH mobile
D.2.4.3 Filtering the aqueous mobile phase
Filtering neutral or basic pH mobile phases is a critical step for removing particulate contaminants
and controlling bacteria.
Figure D–1: SEMs showing the effect of filtering basic mobile phase on an example
column inlet. In the left picture, the mobile phase is unfiltered. In the right
picture, it is pre-filtered.
Restriction:
Never reuse membrane filters.
Required materials
• Chemical-resistant, powder-free gloves
• MS-grade isopropanol
phases).
November 26, 2019, 715003588 Revision C
Page 105