• Heart failure
• natriuretic peptides
• plasma
• microextraction by packed sorbent (MEPS)
• UHPLC-ESI-MS/MS
• sample preparation
• protein precipitation

Heart failure is a condition that develops when the heart does not pump enough blood for the body’s needs. It is an irreversible condition whose incidence can be estimated at 2% and shortly is expected to increase. The diagnosis of the syndrome is challenging due to its non-specific symptoms.
Natriuretic peptides are cardio-specific and sensitive biomarkers normally used to diagnose and monitor heart failure disease. However, their analysis is challenging, mainly due the limitations of immunoassay kits, such as the high cross-reactivity with structurally similar species.
This thesis aims to develop an analytical “top-down” approach for the determination of natriuretic peptides in human plasma, using microextraction by packed sorbent (MEPS) technique coupled to ultra-high performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UHPLC-ESI-MS/MS).
The stability of natriuretic peptides in standard solutions was investigated in different conditions.
The method was validated in terms of linearity, recovery, matrix effect, reproducibility, and limit of detection and quantitation.