
Voyager
™
Biospectrometry
™
Workstation User’s Guide Glossary-1
Glossary
G
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a, b, and c ions
—Generic
description of potential ions that are
formed by fragmentation of a parent
peptide/protein. a, b, and c ions are
fragments that retain the charge at the
amino end (n-terminus) of the molecule.
See also x, y, z ions.
ASCII
—American Standard Code for
Information Interchange. A file format
that contains codes that constitute the
128-character ASCII set, and allows
exchange of data between information
processing systems, communication
systems, and associated equipment.
Accelerating voltage
—
Potential difference between the ion
source and ground, used to accelerate
ions. Actual acceleration in a TOF
instrument usually occurs in the first 1 to
2 cm of the flight tube. Ions then drift the
remaining flight tube distance.
Arcing
—Electrical discharge
between two points. Usually occurs
when a high potential difference exists
between two points.
BA1 and BA2 (Bayard
Alpert vacuum gauges)
—
Pressure gauges that operate below
1 millitorr by measuring a positive ion
current produced by electrons from a
hot filament. Voyager-DE systems
include BA1 only.
Beam Guide Wire
—See Guide
Wire Voltage.
Centroid%
—Percentage of the
peak height examined during peak
identification. For example, with a
Centroid% of 10, the software examines
the top 10 percent of the signal.
CID
—Collision-induced dissociation—
A technology that enhances
fragmentation for PSD analysis. As ions
leave the source, they pass through a
collision cell, interact with collision gas
molecules, and energy is transferred to
the ions. This transfer of energy
enhances fragmentation.
Continuous Extraction
—
Formation of ions in a strong electrical
field, with immediate acceleration. Used
for diagnostic purposes.
Daughter ion
—See Product ion.
Delayed Extraction
—
Formation of ions in a weak electrical
field, with subsequent acceleration by
application of a high voltage pulse after
a predetermined time delay.
CH—CO—NH—CH
Rn
Rn+1
an bn cn
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