Glycerophosphocholine molecular species profiling in the biological tissue using UPLC/MS/MS

A strategy consisting of a two-phase analytical procedure was used to obtain detailed molecular species composition for glycerophosphocholines (GPCs) profiling in biological tissue using ultra performance liquid chromatography coupled with a triple quadrupole mass spectrometer operating under electrospray mode. In phase one of the analytical procedure, the precursor ion scan was first conducted to obtain the preliminary lipid profile that revealed the composition of the molecular species possessing phosphocholine structure in the biological tissue. In phase two of the analytical procedure, each product ion spectrum obtained for the GPC components in the profile was sequentially acquired for the determination of the molecular structure. A simple guide with high differentiability was proposed for the diacyl-, alkyl-acyl- and alk-1-enyl-acyl-GPC, and related lyso-GPCs molecular structure decision. Total 93 GPCs molecular species were identified in the fetal mouse lung with the relative amounts from 14.39% to less than 0.01% (normalizing by the total GPCs signal). The optimized chromatographic conditions were also proposed in the analytical procedure based on the compromise between the separation efficiency and electrospray signal response. The plate number of the probing GPCs was obviously improved to above 30,000 and the detection limits of the probing GPCs were between 0.002 and 0.016. ng/μL. The practical usability of the analytical procedure has been validated using a study of chemically induced early lung maturation. The metabolic difference between chemically treated and untreated fetal mouse lung was clearly distinguished by the composition of GPCs with several characteristics of molecular structure. The overall results showed that this two-phase analytical procedure was reliable for comprehensive GPC profiling.