Pyridine Lab Grade

Pyridine is added to ethanol to make it unsuitable for drinking. In low doses, pyridine is added to foods to give them a bitter flavor, and such usage was approved by the US Food and Drug Administration and is still considered safe by the agency even though external lobbying forced it to ban pyridine's use as a synthetic flavor in 2018. The detection threshold for pyridine in solutions is about 1–3 mmol·L−1 (79–237 mg·L−1).

Pyridine has a flash point of 17 °C and is, therefore, highly flammable. Its ignition temperature is 550 °C, and mixtures of 1.7–10.6 vol% of pyridine with air are explosive. The thermal modification of pyridine starts above 490 °C, resulting in bipyridine (mainly 2,2′-bipyridine and to a lesser extent 2,3′-bipyridine and 2,4′-bipyridine), nitrogen oxides, and carbon monoxide. Pyridine easily dissolves in water and harms both animals and plants in aquatic systems. The permitted maximum allowable concentration of pyridine was 15–30 parts per million (ppm, or 15–30 mg·m−3 in air) in most countries in the 1990s, but was reduced to 5 ppm in the 2000s. For comparison, indoor air contaminated with tobacco smoke may contain up to 16 µg·m−3 of pyridine, and one cigarette contains 21–32 µg.