Qiagen QIAgility, Руководство пользователя

Страница: 37 / 334

General Description
QIAgility User Manual 11/2011 3-13
3.3 Liquid-level tracking
The QIAgility can track the liquid level using 1 of 2 methods:
liquid-level sensing or liquid-level estimate.
Liquid-level sensing
For maximum accuracy and precision, the QIAgility is
equipped with a liquid-level sensor. This feature enables the
instrument to automatically detect when the pipet tip makes
contact with the liquid as the tip descends. When aspirating,
the tip is placed below the liquid surface, at the minimum
insertion depth required to collect the aspirate volume. When
dispensing, the tip is placed at the liquid surface and
retracted as liquid is ejected. This minimizes contact between
the tip and the liquid, reducing liquid carry-over.
The liquid-level sensor relies on conductive tips to detect the
change in capacitance when the tip contacts the liquid inside
a tube — the smaller the volume of liquid inside the tube, the
lower the change in capacitance. For correct functioning of
the liquid-level sensor, it is essential that the plates that are
physically located on the instrument worktable are correctly
assigned in the software. See Section 5.7 for details about
how to do this.
If a liquid is nonconductive (e.g., pure water, oil), the level
sensor will not detect any change in capacitance.
Note : Addition of low concentrations of conductive
substances (e.g., salts) to nonconductive liquids may enable
liquid-level sensing to be used.
Note : To pipet from wells that contain less liquid than the
level sensor limit, it is necessary to switch the level sensor off,
or reset the error detection levels. It may also be necessary to
manually calibrate the plate height closer to the base of the
tube. Alternatively, the liquid-level estimate mode can be
used.
Liquid-level estimate
This feature enables the instrument to estimate the liquid level,
using information from the run configuration. The software