Why is lock mass used in Orbitrap measurements?
['Benzyldimethylphenylammonium was used as an internal lock mass.', "To compensate for drifts in instrument calibration, a compound of known mass is often employed. This 'lock mass' provides an internal mass standard in every spectrum.", 'The use of mass calibrants (lock masses) to reduce the systematic error of mass-to-charge measurements has also been reported and, in some cases, incorporated in the instrument control software by the instrument manufacturers.', 'We achieved absolute mass accuracies for intact proteins between 0.92 and 2.8 ppm using the "lock mass" mode of operation.', 'Real time recalibration on the "lock mass" by corrections of mass shift removes mass error associated with calibration of the mass scale.']
['The lock mass is a compound of known mass and is used to compensate for drifts in instrument calibration.']
[]