Hi , Wanted to know if the immunoassay cut off level of 50 ng is the same as the GC/MS cutoff level of 15ng? If you are at 50ng or less on a home test (negative) does this mean you are at 15ng or less(also negative) on the GC/MS also ? Just confused on the different numbers of 50ng and 15 ng. Can you please explain?? Thanks for any info.