LCMS Quadrupole Resolution Settings

The LCMS method file allows for different quadrupole resolution modes:

• Unit
• High
• Unit
• Custom

These have a peak width at FWHM (Full Width Half Maximum) of:

• Unit resolution is 0.7u 
• High Resolution is 0.4u
• Low Resolution is 2.2u

The Custom resolution allows for a specific value to be set in the Advanced Tab:

Whether setting for Q1 or for Q2, the inputted value will adjust the resolution relative to Unit resolution.

Setting “+15” will narrow the peak width (FWHM) by approximately 0.1 u.

Setting “-15” will widen the peak width (FWHM) by approximately 0.1 u.

This will result in fewer or more stable ions depending on whether narrowed or widened (respectively). Therefore, increasing the resolution (more selective), narrows the peak, resulting in fewer stable ions and a lower overall signal.