Efficacy of plasma phospholipid removal during sample preparation and subsequent retention under typical UHPLC...

Several new products have been marketed with the specific capability of removing phospholipids. These products were evaluated alongside more traditional extraction techniques, using UHPLC and precursor-ion scanning (pre m/z 184), which detects glycerophosphocholines (GPCho), lyso-GPCho and sphingomyelins. Using this technique the plasma GPCho profile of human, dog and rat plasma is briefly compared.

Precursor-ion scanning detected more of the phospholipid profile in extracts than a SRM experiment (m/z 184-184). Products designed for the purpose were the most efficient at removing phospholipids and reversed-phase SPE was better than mixed-mode cation exchange. A comparison of different UHPLC columns demonstrated that C(8) or phenyl phases would help manage the elution of GPChos.

Phospholipid removal plates are useful where no sample concentration is required; however for more challenging LOD it will be necessary to enrich the original sample. In these cases build-up of phospholipids can be avoided with a thoughtful choice of UHPLC column.