In September 2008, it was reported that milk products, especially infant formula, were contaminated with melamine in China. The melamine sickened at least 300,000 infants across the country and killed at least 6. Allegedly, melamine was added to the milk formula and other vegetable protein products, such as wheat gluten and rice protein, to artificially increase the apparent protein levels due to its high nitrogen content. Although melamine itself may have low or no toxicity, it is believed that melamine and related compounds will form insoluble crystals in urine, causing kidney stones and eventual acute renal failure [1]. FDA set thresholds: * At or below 1 part per million (ppm) for melamine and cyanuric acid in infant formula (Nov. 2008) * 2.5 parts per million (ppm) for melamine in foods other than infant formula (Oct. 2008) 300-MS氣相色譜-四級桿質(zhì)譜系統(tǒng)(氣質(zhì) GC/MS和GC/MS/MS)