21 CFR § 189.250 - Mercaptoimidazoline and 2-mercaptoimidazoline.

---
identifier: "/us/cfr/t21/s189.250"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "21 CFR § 189.250 - Mercaptoimidazoline and 2-mercaptoimidazoline."
title_number: 21
title_name: "Food and Drugs"
section_number: "189.250"
section_name: "Mercaptoimidazoline and 2-mercaptoimidazoline."
chapter_name: "FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES"
subchapter_number: "B"
subchapter_name: "FOOD FOR HUMAN CONSUMPTION"
part_number: "189"
part_name: "SUBSTANCES PROHIBITED FROM USE IN HUMAN FOOD"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "21 U.S.C. 321, 342, 348, 371, 381."
regulatory_source: "42 FR 14659, Mar. 15, 1977, unless otherwise noted."
cfr_part: "189"
---


# 189.250 Mercaptoimidazoline and 2-mercaptoimidazoline.

(a) Mercaptoimidazoline and 2-mercaptoimidazoline both have the molecular formula C<sub>3</sub>H<sub>6</sub>N<sub>2</sub>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).