Because carbamates, especially aldicarb sulfone, are unstable, carbamates analyses usually are HPLC based. The US EPA method for monitoring these compounds in drinking water, Method 531, calls for HPLC with post-column derivatization. 1-Naphthol, a fluorescent metabolite of carbaryl, was added to the analyte list in 2003. Our new 531.2 Carbamate Pesticides Calibration Mixture includes 1-naphthol. For stability, we formulate the mix in acetonitrile. We offer the surrogate solution, 4-bromo-3,5-dimethylphenyl N-methylcarbamate (cat.#32274) and the performance check mix (cat.#32275) in our current catalog.