Absolute Quantification of CHO Lipases by Parallel Reaction Monitoring and Stable Isotope Labeled Peptides

Contributing Authors: Timothy Licknack, Ph.D., Stephen Stahlschmidt, B.Sc., Johanna Barnhill, M.S., Alla Zilebrman, Ph.D., and Jared Isaac, Ph.D. Research & Development Department, Chromatography and Mass Spectrometry Group Liquid Chromatography – Mass Spectrometry (LC-MS) is a powerful tool for identifying Host Cell Proteins (HCPs), but most workflows fail to quantify them accurately. Parallel Reaction Monitoring (PRM) combined with stable-isotope labeled (SIL) peptides is a popular approach for absolute quantification. The experiments here display the quantitative accuracy of PRM for targeting Chinese hamster ovary (CHO)-derived lipases. The limit of detection (LOD) for most HCPs is on the order of parts per billion (ppb), while the linear range for some HCPs is at or below 1 part per million (ppm) to many hundreds of ppm. PLBL2 is accurately (+/- 30%) recovered when spiked into drug substance samples (DS) at four concentrations.