Direct quantitative analysis of lysophosphatidic acid molecular species by stable isotope dilution electrospray lonization liquid chromatography-mass spectrometry


In order to better understand the role of lysophosphatidic acid (LPA) in physiology and pathophysiology, it is necessary to accurately determine the molecular species and amounts of LPA in biological samples. We have developed a stable-isotope dilution, liquid chromatography-mass spectrometry assay for the direct quantitative analysis of 1-acyl-LPA. This method utilizes a deuterium-labeled internal standard, LPA (18:0-d35), and a single liquid-liquid extraction with acidic butanol that allows > 95% recovery of LPA, followed by online normal-phase liquid chromatography-mass spectrometry. This protocol allows for the accurate, sensitive, and reproducible analysis of the individual 1-acyl-LPA species present in biological samples. The utility of the assay is demonstrated through the analysis of LPA species in plasma and serum from human volunteers. Total LPA in EDTA plasma was 0.61 ± 0.14 /mM in males and 0.74 ± 0.17 /mM in females, which increased to 0.91 ± 0.23 and 0.99 ± 0.38 /mM after incubation for 24 h at 25°C. Total LPA in serum was 0.85 ± 0.22 μM in males and 1.57 ± 0.56 μM in females, which increased to 4.78 ± 0.89 and 5.57 ± 0.73 μM after incubation for 24 h at 25°C. © 2001 Academic Press.

Publication Title

Analytical Biochemistry