You can reduce cycle time by setting an appropriate draw rate for the syringe. By
default, the system receives feedback from a pressure transducer and applies it to
optimize the draw rate for maximum throughput and performance.
The Loop Offline option reduces the effect of delay volume on cycle time by taking
the needle and extension loop offline before the gradient reaches the injection valve
and after the sample transfers to the column.
Requirement:
Take the loop offline before the first gradient change reaches the
injection valve or after the gradient returns to the initial conditions. To do so, use
solvent at the initial gradient composition. The volume of solvent must be at least
five times that of the combined needle and extension loop. Also, if you intend to take
the needle and optional extension loop offline after the end of the gradient, before
doing so, ensure that they are completely filled with solvent of the initial gradient
composition.
2.5 Preventing leaks
Preventing leaks during an analysis ensures adequate flow pressure in the system
and the integrity of the sample.
Leaks can occur at any tubing connection, gasket, or seal but are most common at
tubing connections. Low pressure leaks (on the intake side of the solvent manager’s
pump) cause solvent loss and air introduction during the intake cycle. Leaks at high
pressure fittings (downstream of the check valves) can leak solvent but do not
introduce air.
To prevent leaks, follow Waters’ recommendations for the proper tightening of
system fittings. Note specifically that different techniques apply to re-tightening
fittings versus installing them for the first time.
2.5.1 Installation recommendations for fittings
Two types of fittings are used within the ACQUITY Arc system: PEEK (polymer-
based) fittings and tubing and SST (stainless steel) tubing and fittings. When
connecting tubing, heed the following recommendations for installing and tightening
fittings.
Warning:
To avoid personal contamination, when handling fittings, wear
clean, chemical-resistant, powder-free gloves when reinstalling fittings.
Recommendation:
June 12, 2015, 715004747 Rev. A
Page 22