Analysis of denatonium benzoate in Oregon consumer products by HPLC

Denatonium benzoate (DB) is being added to a variety of consumer products as an aversive agent or denaturant. In 1995, Oregon was the first state to mandate the addition of DB to antifreeze and windshield washer fluids regardless of whether the product was marketed in a bottle with a child-proof cap. We have modified published high pressure liquid chromatography (HPLC) methods to measure the concentration of DB and validated it for use in Oregon consumer products. Analysis of standards showed a linear curve in the range of 1.25 to 50 ppm. This makes it useful for most analytical applications as DB usually is added in the 10 to 30 ppm range according to DB's manufacturer. The peak analyzed was collected and verified as DB by mass spectrometry. The method was applied to a variety of commercially-available products with particular emphasis on antifreeze and windshield washer fluids which are required by Oregon law to contain an aversive agent. Products analyzed were purchased in either 1994 or 1996 and showed a wide variation in concentration of DB ranging from below the limit of detection in many of the windshield washer products to above 30 ppm in many of the antifreeze formulations. There was no significant change in levels of DB after storage of antifreeze or windshield washer fluids at room temperature for six months.