The preparation of near homogeneous samples of large biomolecules, based on the method of spin coating sample substrates was reported for the first time in 1995 by Perera and collaborators [References, 14].
In the original report [References, 14], samples were deposited on 1″ diameter stainless steel and quartz plates, and large volumes (3-10 uL) of the pre-mixed sample solution were used. The spin coater was home-built and it operated at about 300 rpm, producing evenly spread crystal deposits in air. The samples were very homogeneous and generated highly reproducible and much enhanced molecular-ion yields from all regions of the sample target.
Spin coating the analyte/matrix samples works well and it usually delivers more homogeneous deposits on single-spot sample stages. However, it is not a viable option for MALDI plates with multiple sample wells of the kind found in all modern commercial instruments.