Selection of SPE Cartridge Pretreatment Solvent and Sample Cartridge Flow Rate
1. Pretreatment solvent and parameter selection
We will determine the solvent and its amount and flow rate for pre-treatment and balancing of the SPE cartridge. For a reverse phase cartridge or an ion exchange column, methanol or a polar organic solvent can usually be used as a cartridge pretreatment solution, and water or a buffer solution is used as an equilibrium solution.
The pretreatment of the normal phase cartridge is usually carried out using an elution solvent or a non-polar organic solvent. The flow rate requirements for pretreatment and equilibration of the solution through the cartridge are not critical, as long as the carbon chain of the functional group is effectively extended, and the filler reaches the equilibrium state of the sample.
2. Selection of sample flow rate through the column
The next step is to determine the sample flow rate through the SPE cartridge. The flow rate of the sample through the cartridge is related to the size and size distribution of the particles in the SPE cartridge, the packing density of the filler, the degree of binding of the target compound to the sample matrix, and the viscosity of the sample.
For a reverse phase silica gel cartridge with 100 mg of packing, the flow rate is generally controlled at 2 to 10 mL/min. For the extraction by ion exchange mechanism, since the energy required for the interaction is larger than the non-polar force, the speed of the sample passing through the SPE cartridge should be appropriately reduced to ensure that the target compound has sufficient time and SPE cartridge packing. The ion exchange functional group acts, generally controlled at 1.5 to 5 mL/min.