| Summary: | 碩士 === 國立臺灣師範大學 === 化學系 === 106 === For the analysis of glyphosate, a novel method based on the combination of on-line microextraction and fiber-spray/mass spectrometry was developed. A microextraction kit was designed for this purpose, in which a 2 mL sample vial (reservoir for the sample solution) and a piece of a porous polypropylene hollow fiber (for sample extraction; 3.5 cm in length; O.D./I.D., 1.0/0.6 mm, respectively) were used, respectively. The microextraction kit was located between the mass inlet and the ESI needle. Analytes can be extracted from a very dilute solution operating the so-called hollow fiber liquid phase microextraction process, and the resulting extract then moves to the outside portion of the fiber by diffusion. Following this, the concentrated analytes were evaporated and escape through the porous surface. Meanwhile, the electrosprayed/charged droplets are produced from a regular ESI stainless needle. Once the evaporated materials from the surface of the hollow fiber (mostly neutral) meet the electrospray plume, ionization occurs under ambient conditions. In order to process liquid-phase microextraction, the membrane solution (0.2 M Aliquat 336 in dodecane modified with 4% octanol) and an acceptor solution (0.1 M HCl) were used, respectively. Using the setup, it was possible to improve the limit of detection after microextraction by ∼1000-fold. The limit of detection achieved was 1 ng/mL. When a stir bar was used, the extraction time can be shortened from 60 min to only 15 min.
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