It should be clear that such specific approach may not work for less well known samples. This is a factor 100 longer than with FS scanning, where the dwelling time in the vicinity of the peak is as low as 0.1 seconds. As a consequence, with UniQuant, Detection Limits are better by a factor 10 with respect to SQ programs if the latter are not tailored to sample specific conditions. The most simple case is that of an XRF peak without any spectral interference in its vicinity. The background under the peak can easily be calculated from additional measurements at both sides of the peak.
Any program can do that.
However, the situation is far less simple when a lot of interfering lines are cluttering in the vicinity of the analyte line. It may be impossible to find a spectral position in the vicinity of the analyte line that is suitable to measure a background intensity. In such cases, the background may be determined by considering a wide spectral range, like one would do visually. This is exactly what UniQuant does. Fine-step scanning would not have an advantage.