Section 189.250 - Mercaptoimidazoline and 2-mercaptoimidazoline(a) Mercaptoimidazoline and 2-mercaptoimidazoline both have the molecular formula C3 H6 N2 S. They are synthetic chemicals not found in natural products and have been used in the production of rubber articles that may come into contact with food.(b) Food containing any added or delectable levels of these substances is deemed to be adulterated in violation of the act based upon an order published in the FEDERAL REGISTER of November 30, 1973 (38 FR 33072).