Melamine and cyanuric acid (CA) are low mass, nitrogen-rich compounds that have been linked to protein adulteration in various foodstuffs in the past. While melamine and cyanuric acid are not individually toxic, in combination they can sometimes form an adduct compound through hydrogen bonding, melamine cyanurate, that produce sharp crystals which can cause internal organ failure and possible death.
A similar compound, dicyandiamide (DCD), which is used to minimize the environmental impact of grazing livestock was found in small amounts in dairy products in New Zealand.
Published limits on melamine in infant formula are 1 mg/kg, and 2.5 mg/kg in other foods and animal feed. These values are based on the TDI (tolerable daily intake) of melamine and its analogues of 0.64 mg/kg body weight. Recently a more stringent TDI for melamine and its analogs of 0.2 mg/kg body weight was established. For DCD, the European Food Safety Agency has established a TDI of 1 mg/kg body weight.
As these compounds are quite polar, reverse-phase methods do not typically work well for these analytes. Current methods employ HILIC chemistry or ion pair mechanisms, often with MS/MS detection.
In this application note we describe a method using the ACQUITY UPLC H-Class System coupled to ACQUITY QDa Detector for mass detection, and controlled by Empower Software, for consistent and simple quantification of melamine, cyanuric acid, and dicyandiamide.