Measurement of Neuropeptides in Dialysate by LC-MS

The development of analytical technologies must continue to improve to keep in step with new findings in the neurosciences. Neuropeptides serve a wide range of functions in the CNS and scientists study them intensively for a spectrum of neurological and psychiatric disorders. However, the measurement of neuropeptides in microdialysates has been particularly challenging based on their low basal concentrations in the brain. Here we describe an advanced capillary LC-MS/MS method for the detection of neuropeptides, specifically, methionine and leucine-enkephalin. This chapter is intended to describe a setup in our laboratory which does routine analyses of low picomolar level neuropeptides in dialysates. We describe a procedure for preparing capillary LC columns and how to interface this type of LC system to an ion trap mass spectrometer.