Application MALDI Sample Supports
Prestuctured MALDI Sample Supports: Sample Washing and Recrystallization
As recently shown, prestructured MALDI targets equipped with small hydrophilic patches (“anchors”) on a hydrophobic substrate yield a more than 10-fold increase in sensitivity compared to dried droplet preparations on conventional metal targets, even for fully automated sample preparation and data acquisition. Upon solvent evaporation, the applied μl droplets shrink onto the anchors, thereby increasing the analyte concentration.
Solvent composition is crucial, especially for matrices insoluble in water like a-cyano-4-hydroxycinnamic acid (HCCA). The organic solvent evaporates faster than water and matrix, crystallization starts when matrix saturation is reached. If there is too much water in the droplet, the matrix precipitates too early, resulting in crystallization outside the anchors.