How to do Solid-Phase Extraction

Next the sample and analyte are applied to the column (step 2). This is the retention or loading step. Depending on the type of sample, from 1 mL to 1 L of sample may be applied to the column either by gravity feed, pumping, aspirated by vacuum, or by an automated system. It is important that the mecha- 

Step 3 is to rinse the column of interferences and to retain the analyte (Fig. 1.1). This rinse will remove the sample matrix from the interstitial spaces of the column, while retaining the analyte. If the sample matrix was aqueous, an aqueous buffer or a water-organic-solvent mixture may be used. If the sample was dissolved in an organic solvent, the rinse solvent could be the same solvent. 

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