User`s guide

Chapter 7 PSD Analysis
7-38 PerSeptive Biosystems
7
5. Note the behavior of the signal intensity for the first few
spectra and subsequent continued samplings at a given
laser power.
NOTE: Sample preparations that contain high salt
contamination or other impurities often yield increased
signal intensity after an initial period of low intensity as
the top layer of sample is consumed.
You typically see signal intensity reach maximum and
decrease more quickly than in non-PSD mode as
sample is consumed. You may need to move around on
the sample spot to maintain signal intensity.
6. Continue increasing the laser intensity and observing the
signal. Figure 7-10 shows the effect of higher laser
intensity on the angiotensin I spectrum.
Figure 7-10 Angiotensin I Fragment Ions at High Laser Intensity