When a Raw Supplier gets a Methenolone order, it's like Christmas Morning for them. They'll substitute without a thought. Raws can certainly be Analyzed by mass spec. However, most people don't know that purities can also be determined by HPLC, provided the testing service has a standard to compare. Any reputable Analytical Service will, they subscribe to paid chemical database services (like acdlabs.com). HPLC is relatively cheap compared to other types of Mass Spec Testing.