Molecularly imprinted polymers for selective solid-phase extraction of phospholipids from human milk samples

The authors describe a method for the extraction and determination of phospholipids (PLs) from human milk fat by using a molecularly imprinted polymer (MIP) as the sorbent material and liquid chromatography for detection. The MIP was synthesized by thermal polymerization using L-α-phosphatidylcholine (PC) as the template, methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as the cross-linker, and acetonitrile as the porogenic solvent. The resulting MIP was employed as a sorbent for solid-phase extraction of PLs from human milk fat samples. The extracted PLs were then determined by means of hydrophilic interaction LC in combination with evaporative light scattering detection. Variables affect the extraction efficiency (such as the porogenic solvent, template/functional monomer/cross-linker ratio and extraction conditions) were optimized. The selectivity of the MIP over PLs different from PC was investigated, and the adsorption capacity, breakthrough volume and reusability of the MIP was determined. The MIP displays a satisfactory loading capacity (ca. 41 μg PC per g of sorbent) and a high affinity and selectivity for PC and structurally related PLs, such as sphingomyelin and L-α-phosphatidylethanolamine. The MIP can be reused at least 20 times in case of PL standards, and at least 6 times in case of human milk fat samples.