1. Koichi Tanaka Mass Spectrometry Research Laboratory; Shimadzu Corporation; 1 Nishinokyo Kuwabara-cho, Nakagyo-ku Kyoto 604-8511 Japan
2. School of Agriculture; Meijo University; 1-501 Shiogamaguchi, Tenpaku-ku Nagoya Aichi 468-0073 Japan
3. Analytical and Measuring Instruments Division; Shimadzu Corporation; 1 Nishinokyo Kuwabara-cho, Nakagyo-ku Kyoto 604-8511 Japan