Varian 4000 MS, User Manual

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Scan Function Settings
The 4000 MS method segments control what MS scan function is performed. The
different scan functions in the Internal configuration are EI and CI, full scan,
MS/MS, Multiple Reaction Monitoring (MRM), or Selected Ion Storage (SIS).
Scan Function selection
The 4000 MS has three scan modes - normal speed (5,000 u/sec), fast speed
(10,000 u/sec), or fastest (10,000 u/sec without a prescan). The Fastest speed
only allows acquisition with single-segment mass ranges.
Mass Range Tune
μ
Scans
Normal Fast Fastest
50 – 1000 1 Segment 3 0.76 sec 0.47 sec 0.41 sec
50 – 1000 4 Segment 3 1.08 sec 0.79 sec N/A
50 – 400 DFTPP 3 0.70 sec 0.59 sec N/A
General Parameters Tab
Scan Time
,
Scans Averaged
, and
Data Rate
are all linked. The number of
scans averaged is updated when the scan time is adjusted and vice versa. The
best way to set the scan time is to set the mass range from the Scan Parameters
tab and then change the scans averaged to three. Three scans averaged gives
the best compromise between a high chromatographic data rate and good
spectral averaging.
The
Mass Defect
allows for a systematic correction of the difference between
the nominal mass of an atom (or ion) and its exact mass. Its importance arises