Sample spotting techniques
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Dried droplet
Crushed crystal
Thin layer
Sandwich
Dried Droplet
• Most common method used with all
matrices.
• Premix sample and matrix solution in small
vial (500 µL Eppendorf tube), spot 0.5 - 1
µL onto sample plate and air dry.
• For small sample amounts, deposit 0.5 µL
on plate, then add 0.5 µL matrix on top;
mix and allow to dry.
Crushed Crystal Method
• Prepare a saturated solution of sinapinic acid (or
CHCA) in 30% AcN.
• Deposit 1 µL of this solution on the sample plate
and allow to dry.
• Crush the crystals formed with a spatula or a foilwrapped pencil eraser.
• Add 0.5 - 1 µL of sample in saturated matrix on
top of the crystal layer and allow to dry.
Thin Layer
• Use 10 mg/mL CHCA in acetone. Apply
0.5 µL to plate and dry.
• Place 0.5 µL sample in 0.1% TFA on top of
the matrix layer and allow to dry.
• If sample is not acidified, 0.5 µL 0.1% TFA
can be added to the plate, then the sample.
Sandwich Method
• Deposit 0.5 µL matrix(in acetone or
methanol) on plate and let dry.
• Add 0.5 µL sample in 0.1% TFA, then 0.5
µL matrix (in 50% Acn with 0.1% TFA) and
dry in air.
Ideal Sample Concentrations
• Peptides and proteins: 0.1 to 10 µM
• Oligonucleotides: 10 to 100 µM
• Polymers: 100 µM