1. Animal and Plant Quarantine Agency, Anyang 430-757, Korea.
2. Nanobrick Co., Ltd, Suwon 443-270, Korea.
3. Analytical Toxicology Lab, College of Veterinary Medicine, Cornell University, NY 14850, USA.
4. Laboratory of Toxicology, College of Veterinary Medicine, Seoul National University, Seoul 157-742, Korea.