Lipids are naturally occurring chemical species that are commonly comprised of one or more non-polar hydrophobic hydrocarbon chains and one or more polar portions. Lipids are typically co-extracted with the analytes of interest and generally need to be removed selectively from the matrix to prevent deleterious effects on electrospray ionization, GC liner life, or separations column lifetime. One common method for removing lipids is liquid liquid extraction. In this technique, the sample is allowed to equilibrate with a non-polar solvent. The non-polar hydrophobic hydrocarbon chain partitions into the solvent, leaving the polar analytes in the polar solvent. If the lipid has a large polar portion, the non polar solvent may or may not completely extract the lipid from the polar solvent. The drawback to this approach is high solvent usage and lengthy procedures.
Another common approach for lipid removal is to expose the extract containing the analyte and the lipid to a strong Lewis Base like alumina. The d orbitals on alumina are deficient in electrons so they react with Lewis acids to fill the orbitals. Phosphate moiety, for example, is a strong Lewis acid that has a high affinity for an alumina surface. The drawback of this approach is when the number of Lewis base sites exceeds the number of Lewis acids. The Lewis base will start to react with your sample and sample losses occur. Alternatively, the metal will chelate with chelation groups of oxygenated polar hydrocarbons. The only way to remove these groups is with sodium EDTA or equivalent strong chelator.
United Science offers a variety of lipid removal materialsincluding C18, LipidX, CarbonX Plus Lipid Removal. These can be configured into dual phase SPE, tri phase SPE, Universal QuEChERS, and other dSPE additives.
- Universal QuEChERS incorporates C18 into the dSPE Mix for lipid removal by partitioning of the non-polar hydrocarbon tail into or onto the bonded C18 phase. CarbonX is included in this QuECHERS mixture. Use for all sample types without losing your analyte.
- QuEChERS dSPE additive LipidX will remove lipids based on solid supported liquid extraction. The nonpolar solvent immobilized in the pores of this material selectively removes nonpolar hydrocarbon chains such as common with all lipids.
- QuEChERS dSPE CarbonX Plus Lipid Removal materials will remove lipids based on Lewis Base/Lewis Acid interactions. The material is distinct from our standard QuEChERS carbon (CarbonX Plus). The material is comprised of carbon that has affinity for the nonpolar tail and Lewis Base alumina that has affinity for the polar head.
- C18 cartridges are available in a variety of cartridge sizes and layers.
- Dual phase SPE is highly effective for removal of a variety of matrix components.
- United Science offers the customer the option to select the lipid removal material that they would like to configure into a dual phase SPE cartridge.
- Traditional lipid removers such as C18 are available. Other lipid removal options include CarbonX materials. PSA.
- Optional C18 layer will remove lipids on the basis of large nonpolar chains.
- Optional Alumina layer will remove polar moiety on lipids including a high selectivity for phospholipds.
- Optional CarbonX COA is a mixed mode material that has only a limited amount of alumina lewis acid sites exposed.
- Avaialable in SPE, dSPE, and in guard cartriges.
- Reverse Phase SLE
- Nonpolar solvent solid support for extraction of nonpolar moiety.
- Will remove nonpolar matrix components but not polar matrix components.
- Small number (10%)of Lewis acid sites exposed
- Remaining material is covered with carbon.
- Both polar and hydrophobic selectivity.
- Low lipid capacity for “Just Enough” application.