You can acquire and display mass spectral data (intensity versus m/z) as profile data or as centroid data.
- Profile data—With profile data, you see the inherent shape of the peaks in the mass spectrum. The mass spectrum divides each atomic mass unit into several sampling intervals. The intensity of the ion current is determined at each sampling interval. The intensity at each sampling interval is displayed with the intensities connected by a continuous line. Profile data is a good way to see the isotopic distribution, especially for higher charged ions.
- Centroid data—With centroid data, you see the mass spectrum as a bar graph. This scan data type sums the intensities of each set of sampling intervals. This sum is displayed versus the integral center of mass of the many sampling intervals. An advantage of centroid data is that it requires about one-tenth the computer disk space of profile data. However, with centroid data, you lose information about the fine isotope features and the linearity of the ion signal.
When you run SRM methods, the data is automatically collected in centroid mode.