In a case of insoluble substances there is a way to obtain MALDI mass spectra which is based on thorough grinding of the sample with crystalline matrix (for instance, in vibration mill). The quasi homogeneous mixture obtained can be applied on a target plate. This method works good for some polymers, but there are a lot of compounds which cannot be analyzed using such "dry" technique.  

Thank you for your support. I will go through the journal and get back back to you shortly.