Determination of Herbicide Residues in Groundwaters Using Liquid/Liquid Extraction and Off-line Purification with Liquid Chromatography-Mass Spectrometry

Solid phase extraction-Liquid Chromatography-Mass Spectrometry is a commony method for the determination of triazine and amides herbicides in groundwater. In order to overcome the disadvantage of the long processing time for current analysis procedure and instruments, a new method has been established, which uses HLB solid-phase extraction, elution reagents of methylene chloride-acetone (V : V=4 : 1) and a fluorine florisil column as the purification column. 14 kinds of triazine and 2 amides herbicides in groundwater were measured by Liquid Chromatography-Mass Spectrometry. The influence factors of mass spectrum conditions, solid-phase extraction column, elution solvents and purification columns were studied. Extending the scanning time of quantitative ions can reduce the relative standard deviation for most of the target components, and improve the stability of the instrument. The polarity of elution solvents greatly influences the recoveries of target components. Methylene chloride-acetone (V : V =4 : 1), which is more polar solvent, can obtain higher recoveries. The fluorine florisil column was used to remove interfering substances, reducing the matrix effect. The results show that the detection limits of 14 kinds of triazine herbicide and 2 amide herbicideare are less than 0.40 μg/L. The results are accurate and stable, with the recoveries of all herbicides between 85.8%-103.1% at 0.50 μg/L, and relative standard deviations between 5.2%-8.6%. However, this method has a lot of overlap peaks, but the analysis time is significantly shorter than current methods (5 min compared to 15 min or more), and meets the daily needs of large quantities of water sample testing.