A Cost‐Effective Hybrid Method For Homogeneous Matrix Coating in Matrix‐Assisted Laser Desorption/Ionization Mass Spectrometry Imaging Using Simultaneous Spin and Spray Deposition

A cost‐effective, thin‐film spin‐coating method for homogeneous matrix deposition in matrix‐assisted laser desorption/ionization mass spectrometry imaging (MALDI‐MSI) is presented. In this method, the matrix solution is nebulized directly onto the sample surface during continuous rotation in the spin coater, enabling simultaneous spraying and centrifugal spreading for uniform film formation. Although spin coating produces highly uniform matrix layers, its widespread adoption in MALDI‐MSI is hindered by the high cost of commercial instruments. To address this limitation, an in‐house spin coater is developed and optimized. A fractional factorial design identified flow rate, matrix volume, and rotation speed as the most critical parameters for achieving uniform deposition. Under optimal conditions (60 psi, 10 µL·min −1 , 400 µL, and 10 cm at 35 a.u.), the system produces homogeneous matrix films across entire glass slides. The effectiveness of this integrated spray during spin method is demonstrated by imaging the distinct spatial distributions of key lipids and metabolites in mouse brain, strawberry, and carrot tissues. This work establishes the in‐house spin coater as a feasible and robust tool for enhancing reproducibility and data quality in routine MALDI‐MSI workflows.