true use: Is there a more accurate test for true B12 than the current one that uses Lactobacillus Leichmannii...?

i.e. to differentiate the cobalamins from the similar but ineffective corrinoids.Is there a more accurate test for true B12 than the current one that uses Lactobacillus Leichmannii...?
well you get three points for picking a BA....I could use it since someone has been reporting me the last few days