Analytical Sciences

A New On-line Sample Preparation System for the Liquid Chromatography/Time-of-Flight Mass Spectrometry Simultaneous Analysis of Pesticides in River Water

Hideki SASAKI,* Jun YONEKUBO,* and Kazuichi HAYAKAWA**

*Nihon Waters K. K., 3-12, Kitashinagawa 1-chome, Shinagawa, Tokyo 140-0001, Japan
**Graduate School of Natural Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan

Current on-line solid-phase extraction methods combined with HPLC for shortening the clean-up operation are not suitable for simultaneously detecting compounds that have a wide variety of hydrophobicities. To solve these problems, we designed a new on-line sample preparation system. The system consists of an eluting pump, a mixing TEE connector, a 10-port 2-position valve and a solid-phase extraction precolumn. The eluate from the precolumn is diluted with a weak solvent from the HPLC at the TEE connection to load low hydrophobic compounds onto the analytical column. The proposed on-line sample preparation system was successfully applied to the simultaneous analysis of 21 pesticides in river water using LC/TOF-MS. In this method, the recoveries from river water samples were 67 to 126% (mean 83%), the reproducibility (CV%) was in the range from 1.1 to 11% (mean 5.6%), the calibration curve was linear in the range from 1 ppb to 500 ppb (r > 0.999) and the detection limits (S/N = 3) were in the range from 0.0034 ppb (daimuron) to 3.3 ppb (oxine-copper).

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