Technical Note – Improving Sensitivity for an Immunocapture LC-MS Assay of Infliximab in Rat Plasma Using Trap-and-Elute MicroLC-MS

Using the SCIEX M3 MicroLC system for Increased Sensitivity in Antibody Quantitation

Remco van Soest and Lei Xiong
SCIEX, Redwood City, CA, USA

Quantitation of monoclonal antibodies (mAbs) in biological fluids is important during all stages of antibody drug development. While traditionally immunoassays are used, more recently LC-MS has been adopted because of its high selectivity, accuracy, and precision. The antibodies can be enriched from sample using different approaches, e.g. solid phase extraction or immunocapture, and then digested using trypsin. Unique signature peptides are selected based on criteria such as digestion  efficiency, stability after digestion, chromatographic behavior and MS-MS sensitivity, and then measured using LC-MS in MRM mode. As the amount of sample that  can be drawn from a small animal during DMPK studies is limited, sensitivity of an LC-MS based method becomes very important.

Key Benefits of using the M3 MicroLC system for Antibody Quantitation

  • Antibody quantitation at levels up to 10 x lower than what can be measured with High Flow LC-MS
  • High throughput by using a Trap-Elute workflow
  • Increased column lifetime and reduced need for cleaning of the MS by protecting the analytical column and MS from salts and other impurities that were removed  uring the Trap-Elute workflow