Typically a FAME analysis is performed with an FID not NMR. There are many methods online and IS selection depends on the source of your biodiesel. Check the Thermo Scientific and Restek websites.
FAME analysis can be easily carried out with GC with an FID detector. A polar column like FAME WAX from Restek Corporation can provide baseline separation. There are optimized Bio-diesel analysis methods available from Shimadzu Corporation, Japan.