Solid phase extraction procedures and precautions
For the different retention mechanisms of fillers (fillers retain target compounds or impurities), the operation is slightly different. 1) There are generally four steps in the solid phase extraction operation for the retention of the target compound in the packing: Activation-remove impurities in the cartridge and create a certain solvent environment. (Be careful not to let the small column dry up during the whole process.) Loading-Dissolve the sample in a certain solvent, transfer it to the column and keep the components on the column. (Pay attention to the flow rate not to be too fast, preferably 1ml / min, the maximum is not more than 5ml / min) Rinse-remove interferences to the greatest extent. (It is recommended that the cartridge be completely drained after the end of this process.) Elution ---- Use a small volume of solvent to elute and collect the substance to be tested. (Note that the flow rate should not be too fast, preferably 1ml / min)
Effect of p H value on solid phase extraction
The pH value can change the degree of ionization or protonation of the target / adsorbent. For Qiangyang / Anion Exchange Column, because the adsorbent itself is fully ionized, the target must be fully ionized to ensure that it is completely adsorbed and retained by the adsorbent. The degree of ionization of the target is related to the pH value. For weak basic compounds, the pH value must be less than two units of their pKa value to ensure complete ionization of the target, while for weak acid compounds, the pH value must be greater than two units of their pKa value to ensure its complete Ionization. For weak anion / cation exchange columns, the adsorbent must be fully ionized to ensure complete adsorption of the target, and the pH value of the solution must meet certain conditions to ensure its complete ionization.
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