Answer:
The field-free drift path
Explanation:
In MALDI-TOF, the sample is embedded in a matrix. A laser vaporizes the molecules in the sample with little fragmentation. The gaseous molecules are ionized, accelerated, and sent through a field-free drift path to the detector.
The proteins in the sample have different velocities based on their mass-to-charge ratio.
The fastest ions are those with the smallest m/z ratio.
The field-free drift path increases the separation between the ions, so the smallest ions reach the detector first.
Thus, the ions are separated based on their time of flight through the drift tube.
