Determination of denatonium benzoate in cosmetics and their antifeeding property

A method for the determination of denatonium benzoate, benzyldiethyl-N-2,6-xylylcarbamoylmethylammonium benzoate, abbreviated to DB, in cosmetics was developed. A cosmetic sample of 1-2 g was weighed and dissolved with methanol up to a volume of 10 mL. When a precipitate was seen, it was cleared using a high speed centrifuge. The solution was loaded on a cation exchange column, washed with methanol, and eluted by 1% HCl-MeOH 10 mL. The eluate was evaporated to dryness, dissolved by 0.1% HCl-MeOH 500 kL, and injected on an HPLC. The conditions for HPLC were as follows: column ODS, mobile phase water/acetonitrile (7:3) containing 0.01 mol/L sodium 1-pentanesulfonate and 0.015 mol/L sodium sulfate, injection volume 20 kL, detector 206 nm. The detection limit was 0.1 ppm. By this method, 1.0 to 9,000 ppm of DB were detected in five imported cosmetics without any interference. A 1.0 mL of 1.0 ppm DB water solution fully convinced us of DB's antifeeding property because of the intense bitter taste. We have rarely seen Japanese cosmetics or household articles containing DB as aversive agents to prevent accidental ingestion, but there are many and wide ranges in US or European articles.