The matrices and betaine aldehyde were applied on the Wssue using SunCollect sprayer system (SunChrom GmbH, Friedrichsdorf, Germany). The flow rate of the betaine aldehyde soluWon [1mg/ml, ACN:H2O, 2:1 v/v] was 60 µl/min, and 3 layers were put on the Wssue. The nozzle spayed betaine aldehyde linearly at 2 mm intervals with a spraying nozzle speed of 800 mm/min. PosiWon of the spraying nozzle was Z=5 (high posiWon above the Wssue).