Answer 9.4

a) What is the difference between BE and EB instruments when it comes to their use for MIKES?

In EB instruments, the electric sector (E) precedes the magnetic sector (B). Vice versa, reverse geometry is realized by the BE type of magnetic sector instruments. There is virtually no difference between EB and BE in normal operation.
However, when it comes to MIKES the BE setup is needed. Just think of the term „mass-analyzed ion kinetic energy spectrometry“: mass-analysis (B) prior to detection of ion kinetic energy (E) is required.

b) Double-focusing magnetic sector instruments can be operated in numerous scan modes for tandem MS. Some these require more than one parameter to be varied for a scan. How are those methods termed?

They are termed „linked scans“ because two field a altered in mutual dependence.

c) Right or wrong?

  1. B/E = const. linked scans offer good precursor ion resolution: Wrong.
  2. The accurate mass of fragment ions cannot be determined when using B/E = const. linked scanning: Right.
  3. BEBE and EBEB instruments have extensively been used for tandem MS to sequence peptides: Right.
  4. Four sector instruments are compact and ecomonic: Wrong.
  5. Tandem MS on magnetic sector instruments pioneered gas phase ion chemistry: Right.