Solid phase extraction is an important application of chromatography. In this method, a certain volume of the sample solution is passed through a small column containing a solid adsorbent, and the component having a strong action with the adsorbent in the sample is completely adsorbed; then, the adsorbed component is washed with a strong elution solvent. Take it out and fix it into a small volume of the sample solution to be tested. Solid phase extraction is used to concentrate the components in the sample while preliminarily removing components that interfere with the component of interest, thereby increasing the sensitivity of the assay. The solid phase extraction device can be used not only for sample pretreatment in chromatographic analysis, but also for sample pretreatment of various analytical methods such as infrared spectroscopy, mass spectrometry, nuclear magnetic resonance, ultraviolet and atomic absorption. The C18 solid phase extraction cartridge has a hydrophobic action and adsorbs non-polar components, so the polynuclear aromatic hydrocarbons can be extracted from the water to complete the concentration of the sample. There are other types of solid phase extraction cartridges, such as polarity, ion exchange, and the like. [Instruments and reagents] C18 solid phase extraction cartridge: 2 is actually a simple WatersSep-Pak-C18 solid phase extraction cartridge (the filler is octadecyl bonded silica gel, particle size 40 microns, column volume is 1mL) 25 mL pipette: 1 50 mL medical syringe: 1 10 mL medical syringe: 2 2 mL volumetric flasks: 2 water samples containing naphthalene and phenanthrene. [Solid phase extraction operation method] (1) Solid phase extraction cartridge pretreatment: 3-5 mL of acetone is pressed through a small column with a 10 mL syringe, and then 3-5 mL of pure water is pressed through the column. At this point, the material in the cartridge that can be eluted by acetone is no longer present. (2) Take 25 mL of water sample with a pipette and press the column with a 50 mL syringe. At this time, the naphthalene and phenanthrene in the water sample are adsorbed on the small column and cannot be eluted by water. (3) A 2 mL volumetric flask was taken at the lower end of the small column, and about 1.5 mL of acetone was pressed through a small column into a volumetric flask with a 10 mL syringe, at which time all naphthalene and phenanthrene were washed out with acetone. Add a known amount of the internal standard and shake to a constant volume to obtain a concentrated sample.
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