The MALDI mass spectrometry method comprises the provision of a test composition comprising an analyte, a matrix material, a solvent for the matrix material and an antisolvent, which facilitates crystallization of the matrix material on the analyte subsequent to droplet generation. Due to the crystallization, a non-spherical particle morphology of the test sample is obtained. The test sample with a non-spherical particle morphology can be distinguished from test samples with an at least substantially spherical particle morphology by sensing a morphology parameter. Based on the sensing result, test samples with a non-spherical particle morphology are selected for ionization and mass spectrometry. The antisolvent is for instance water, and the solvent is an organic solvent. The formed crystals are in one embodiment crystallized in a hydrate form. As a result, a signature-rich spectrum is obtained.