Polymorphism of DS in formulation

Which technology is available to check the polymorphism of API in solid formulation (DS% in DP is 0.4% and 0.1% or 2.0 and 0.2 mg/capsule). Is the validation of such a method possible?
XRPD is not sensitive enough Raman or other spectroscopy methods are under consideration, but what is the LOD of such methods?
Thank you