Department of Biochemistry
Calibration Standards

MALDI Related Protocols


Peptide sample is optimally dissolved in water or 10% ACN, 0.1% TFA, and contains minimum salt content.


max buffer/salt content


Protein samples are optimally dissolved in water or 2 mM ammonium bicarbonate.  The sample is mixed at 1:1 ratio with the matrix and spotted onto MALDI target (spot volume, 0.75 µL).


MALDI Mass Spectrometric Imaging (MSI)

An air brush sprayer or sublimation techniques are used to apply the matrix over tissues mounted onto MALDI plate.


GM1: brain imaging


Alzheimer's disease rat brain tissue imaging of ganglioside GM1c18 by MALDI MS.  Decreased GM1c18 expression was observed in the stroke region and stroke periphery (right side).



Commonly used MALDI matrices:


alpha-cyano-4-hydroxycinnamic acid (CHCA)

CHCA is the most common matrix used for basic and neutral proteins and peptides.  It is prepared as 5mg/mL in 50% ACN, 50% water, and 0.1% TFA.  Alternatively, instead of water, 25mM ammonium citrate or 6mM ammonium phosphate monobasic can be used to suppress matrix signals.

2,5-dihydroxybenzoic acid (DHB)

DHB is used for acidic and phosphorylated peptides.  It can also be used for organic molecules (carbohydrates, synthetic polymers).  It is prepared as 20mg/mL in 15mM ammonium citrate, 20% ethanol, a 1% phosphoric acid.

sinapinic acid (SA)

SA is generally used for high protein masses (>20kDa).  However, it is particularly appropriate for highly acidic and phosphorylated proteins.  It is prepared as 5mg/mL in 50% ACN, 50% water, and 0.15% TFA.  Alternatively, 25mM ammonium citrate is used instead of water.


In addition:

2,4,6-trihydroxyacetophenone (THAP) is used for low mass oligonucleotides (5000Da);
2-(4'-hydroxybenzeneazo) benzoic acid (HABA) is used in polymer and dendrimer analysis;
5-chloro-2-mercaptobenzothiazole (CMBT) and 1,5-diaminonapthalene (DAN) are used for ganglioside imaging;
T-2-(3-(4-t-Butyl-phenyl)-2-methyl-2-propenylide) malononitrile (DCTB) is used to analyze fullerene derivatives;
dithranol and trans-3-indoleacrylic are used for polymer analysis.


 

 

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