Stable association complex electrospray mass spectrometry for the determination of cyanuric acid

Cyanuric acid, a suspected gastrointestinal or liver toxicant, has gained i nterest as a potential degradation product of triazine herbicides, such as simazine and atrazine. This paper investigates the determination of cyanuri c acid by stable association complex electrospray mass spectrometry (cESI-M S). The cyanuric acid is extracted from the water through a microscale liqu id-liquid extraction. The extract is evaporated to dryness, and an aqueous solution of quaternary ammonium cationic surfactant is added. When injected into the electrospray mass spectrometer, the surfactant and the cyanuric a cid form a mass-selective stable association complex, which may be used for confident quantification of cyanuric acid. Several extraction solvents and surfactants were investigated. These studies provide insight into the mech anism of electrospray for the formation of these complexes, specifically wi th regard to the surface activity of the different surfactants and the chem istry of the surfactant-cyanuric acid complexes. From an analytical standpo int, the cESI-MS method detection limit for extraction of a 1 mL aqueous so lution of cyanuric acid was 130 mug/L based on 3.140 sigma (n-1) of seven r eplicate injections. Standard additions were used for quantification of eig ht aqueous samples. The cyanuric acid concentrations determined with cESI-M S were not significantly different at the 95% confidence level to those det ermined by conventional high-performance liquid chromatography (HPLC). A re covery of 100% from a fortified urine sample illustrates the robustness of the technique. (C) 2001 American Society for Mass Spectrometry.