Bioanalysis Strategies of Polypeptide LC-MS in Biological Matrices – A Case Analysis of Glucagon and Its Analogs in Plasma

Abstract

Glucagon and its analogs are polypeptide drugs developed for treating metabolic conditions such as hypoglycemia, diabetes, and obesity. Due to their high potency, these drugs are typically present at low concentrations in plasma during pharmacokinetic (PK) studies, requiring a highly sensitive bioanalytical method. This work describes a rapid and sensitive LC-MS/MS method using protein precipitation (PPT) with acidified acetonitrile for sample preparation. Analytes were separated on an ACE C18 column using a linear gradient of water and acetonitrile with 0.1% acetic acid. Detection was performed on an AB Sciex mass spectrometer in positive electrospray ionization mode, using the 5+ charge state as the precursor ion. Selective MS/MS fragment ion monitoring improved signal-to-noise ratio and minimized endogenous interference. The assay demonstrated a linear range of 0.5–500 ng/mL with high accuracy, precision, and robustness. It offers high sensitivity, selectivity, low matrix effects, and is suitable for routine PK analysis with high throughput and low cost.

Keywords: LC-MS/MS, Polypeptide bioanalysis, Glucagon, GLP-1, GLP-2, Plasma matrix