Acquisition Scan Window UI

This window displays in Manual Tune > Acquisition when Scan is selected in the Acquisition Type menu.

Scan Parameters area

Low and High (m/z) - Enter the low and high masses (m/z) to specify the range to be scanned by the MS. The larger the range, the lower the scans/second. Low to high mass must be in ascending order. 

The valid range for scans on a 5977C MSD is 0.6 m/z to 1091 m/z. The valid range for scans on the 5975, 5977A, and 5977B MSDs is 1.6 m/z to 1050 m/z.

Step size (m/z) - Use this field to set the mass step size for scans. The larger this value is the faster scans are taken (at the cost of resolution). The range of this value is 0.1 m/z through 0.5 m/z (10 acquisitions/AMU to 2 acquisitions/AMU).

Speed - The number of abundance samples to average during a 0.1 amu step. A sampling rate of 4 to 8 is typical for narrow bore capillary columns. We recommend that you select the same sample value for tuning and for data acquisition.

Averages - Use this field to set the number of profile scans to be averaged for each scan reported or displayed. Allowed values are 1 through 32. The smaller this number the faster the scan times. A higher number causes slower acquisition of tuning data but is useful for tuning small or very noisy signals.

Threshold - Use this field to set the peak detection threshold, which determines what signals are accepted as peaks. The lower the threshold value, the more mass peaks are detected. The higher the value, the cleaner the spectrum. Typical values range from 0 to 500. At each 0.1 m/z step, the current signal along with the four previous signals is used to calculate a weighted average. If the average is greater than the threshold, the current signal is accepted as a mass peak and is saved.

Run

Data is continuously acquired and displayed in the Spectrum window until you click Stop acquiring data .