The answer is dependent on the substance you are analyzing and the
industry you are analyzing it for.
You are on the right track. Look in references for testing the substance
in your industry. If you are in the medical industry, look for methods
published in medical journals. If there are none, you might try
references in environmental journals and publications next.
Beware. If this is for GLP, the further you are from a medically
accepted method, the more extensive the validation work you
will be required to do.
Good luck.