Analysis of Herbicides in Water by On-Line In-Tube Solid-Phase Microextraction Coupled With Liquid Chromatography-Mass Spectrometry

We have developed a method using in-tube solid-phase microextraction coupled with liquid chromatography-mass spectrometry (SPME-LC-MS) for the assay of herbicides in water samples. Chlorinated phenoxy acid herbicides have been automatically extracted into a DB-WAX capillary by repeated draw/eject cycles of sample solution and desorbed with acetonitrile. Triazine herbicides have also been extracted easily by this in-tube SPME method. Compared with direct sample injection into LC-MS, the in-tube SPME technique resulted in a greater than 25-fold concentration. The automated in-tube SPME-LC-MS system can continuously extract herbicides from aqueous samples, followed by LC-MS. It provides a simple, rapid, selective, sensitive, low-cost method for herbicide analyses and can be directly applied to various water samples without any pretreatment. Although the in-tube SPME technique has not yet been extensively applied, its application to various fields is expected because the analytical processes, from sample preparation to chromatography and data analysis, can be automated.