• A saturated matrix solution is prepared in ACN-H20 or MeOH-H2O

• A droplet (0.5 uL) is deposited on the MALDI target

• The same volume of analyte solution is deposited onto the either dried or wet matrix drop

• Molar ratios of matrix:analyte are usually > 1000.

• The sample is allowed to dry and is ready for MALDI-TOF analysis

https://application.wiley-vch.de/books/sample/3527333312_c01.pdf

Detection of hemoglobin mutant (beta79D-E) by MALDI-MS

normal

Hb Miyazonomutation

Y. Wada, J. Chromatrogr. B 781, 2002, 291.

MALDI-MS can analyze mixtures of smaller molecules,

e.g. standard peptides. (M+H)+ ions are observed.

Bradykinin

Angiotensin II

Substance P

Angiotensin I

Bombesin

ACTH 1-17

ACTH 18-39

Exact mass: 952.5098

High resolution (10000)

Monoisotopic peak

C = 12.000

H = 1.007825

N = 14.003074

O = 15.9949146

S = 31.972071

http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532012001200002

Advantages:

More tolerant to impurities than electrospray

Allows solid samples to be stored and reprocessed

Direct mass measurement (single charging) due to TOF analyzer

Good for non volatile, thermolabile and high MW compounds

Mixture analysis possible

Disadvantages:

Dry plate does not allow interfacing with liquid flow technique

Very high vacuum required (10-7 torr)

Quantitation difficult due to surface roughness

Very little fragmentation