How Does the Channel Alignment Function on a SCIEX TripleTOF® System?

For research use only. Not for use in diagnostic procedures.

Answer

The basic functioning of a detector for a TOF instrument has not changed too much since the QSTAR® system of TOF-based mass spectrometers, and the signal is detected as described below:



A TOF detector has two micro-channel plates (MCPs) sandwiched together that serve to detect single particles and to multiply the signal. After a particle impinges on an MCP and is amplified, the signal is split into four channels at the anodes.

The purpose of channel alignment is to re-align the signals from each detector/TDC channel in time. Channel 2 is used as the reference channel, and a simple linear transformation is applied to the other three channels to align them to the reference. A channel alignment operation is performed to determine the coefficients for that linear transformation.

Alignment is necessary to compensate for any inconsistencies between the channels (e.g., imperfect flatness of MCPs, slight differences in electronic delay). If alignment were not performed, then peaks for the same ion may have slightly different flight times on different channels, resulting in a loss of resolution when they were recombined.