SPE is an efficient, reliable and convenient method for sample pretreatment. It is considered a revolutionary advance in pretreatment because of its low use of organic solvents, its ability to process samples in bulk, and its ability to concentrate and remove impurities.
The basic principle of antiphase bonded silica gel is nonpolar interaction. Since the silica gel is only the main body, there is a small part of the presence of silicone methanol, so there are some polar second-order interactions.
How ion-exchange solid phase extraction preserves a compound depends largely on the pH of the sample and the pretreatment solution. In order to preserve the compound, the pH of the sample should ensure that the functional groups on the analyte and on the silica surface are negatively charged.
Regarding the pretreatment of soil and sediment in SPE, generally extracted by Soxhlet extraction or ultrasonic treatment with medium to nonpolar solvents.
Regarding the pretreatment of plant tissues, fruits, vegetables, and agricultural products in SPE, shall be homogenized with water, polar solvents, or mixtures of water and these solvents, and purified by reverse phase and ion exchange.
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