3P-04 PDF
Ultrasensitive Quantification Assay for Oxytocin in Human Plasma Using a LC/MS Microfluidics Platform
Oxytocin (OT) is a 9 AA cyclic peptide (CYIQNCPLG-NH2) that acts as a neurotransmitter in the brain and is typically present at low pg/mL concentrations in human plasma1). Here we repot on a single dimension LC-SRM method developed on a prototype microfluidic platform (operating with flow rates in the of 1-5μL/min) able to detect endogenous levels of OT in human plasma. Human plasma samples (300 uL) were spiked with an internal standard peptide (octreotide) and mixed with 300 uL of 4% H3PO4. Samples were clean-up on a WCX mixed mode (weak cation exchange/reversed phase) SPE micro-elution plate and eluted with 50 uL of 50% ACN containing 1% TFA. After 1:1 dilution with 0.1% formic acid in DI water, 1 uL of sample was injected on a microfluidic platform containing a separation channel of 150 µm ID x 5 cm operated at a flow rate of 4µL/min. Our assay achieved an LLOQ of 5 pg/mL for oxytocin in human plasma with a plasma aliquot size of 300 μL.