Thermo Scientific Accela Open Autosampler Hardware Manual page 111

Tube Not Cut Square
Thermo Scientific
Figure 58. Pressing the tube into place
Failure to observe this procedure will lead to an incorrect pilot distance, which will result in
actual dead volume, not delay volume.
All tubes have to be cut absolutely square
dead volume, which yields carryover and other chromatographic effects. This rule is valid for
stainless steel, PEEK, or Polymer tubing. The material is not decisive, but using the correct
tool for each material when cutting a tube is.
Stainless steel tubes are often cut by using pliers. Often, an egg-shaped profile results, which
no longer seals and causes dead volume. Dedicated pliers for HPLC tubing are available on
the market; nevertheless, for best results, use precut tubing which is cut smooth and clean,
and is passivated.
Because polymer tubes, such as PEEK, Teflon, PFA, and so on are soft, you might choose to
cut them with any handy tool. Commercially available tubing cutters from many
manufacturers are available. If the blade does not provide a clean, right-angle cut, however,
use a different technique.
The most reliable and common way to cut tubing of any material is with a cutter that has an
adjustable blade. Carry out the initial turns, readjust the blade, turn once more, and adjust
again until approximately half of the tubing wall is cut. Hold the tube on the two sides of the
cut with flat-nose pliers and twist the tube until it breaks. You can use the same procedure for
polymer tubing by replacing flat-nose pliers with tweezers with a flat tip.
(Figure 59). Any deviation from square causes a
Accela Open Autosampler Hardware Manual
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Troubleshooting
Troubleshooting Considerations
93