
Chapter 5 Optimizing Instrument Settings
5-20 PerSeptive Biosystems
5
Spectrum Acquisition (continued)
Low Mass Gate (Da) Turns on the detector voltage after the ions of the Mass
specified have passed the detector. Ion masses below this
entry are not considered during analysis.
Suppresses matrix peaks that can interfere with ion
detection, and saturate the detector as laser intensity
increases.
Turn on Low Mass Gate when:
• Analyzing masses greater than 2,000 to 3,000 Da
• Matrix signal is much higher than the sample signal
NOTE: Low mass gate is automatically disabled when you
change the instrument mode to PSD.
See Section 5.4.4.5, Setting Low Mass Gate, for more
information.
Calibration
Matrix Displays the matrix used for the analysis. Available
matrices in this field are:
•
α
-cyano-4-hydroxycinnamic acid
• Sinapinic acid
• 2,5-Dihydroxybenzoic acid
• 3-Hydroxypicolinic acid
If you do not specify a matrix, a default value of 300 m/sec
is used.
Corrects for the initial velocity contributed by the matrix,
for a more accurate calibration
1
,
2
. Correction factors for
each matrix are listed in “Matrix influence” on page 5-22.
If your matrix is not listed, you can add other matrices to
this list by editing the Matrix reference file. For
information, see “Modifying the matrix reference file” on
page 5-23.
Table 5-4 Instrument Settings Parameters (Continued)
Parameter Description
Comentarios a estos manuales