In‐tube solid‐phase microextraction (sulfopropyl methacrylate‐co‐ethylene glycol dimethacrylate monolithic capillary) coupled to LC–MS/MS to determine beta amyloid peptides in Alzheimer's cerebrospinal fluid samples

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by an extracellular accumulation of amyloid beta peptides in the brain. The concentration of the amyloid beta peptides in cerebrospinal fluid (CSF) have been evaluated as potential biomarkers of AD for early diagnostic. In this work, an in‐tube solid‐phase microextraction (in‐tube SPME) coupled to UHPLC–MS/MS method was established to determine amyloid beta peptides in CSF samples from AD patients. A strong cation‐exchange (sulfopropyl methacrylate‐co‐ethylene glycol dimethacrylate) monolithic capillary was synthesized on the inner surface of a fused silica capillary and used as an extractive phase for in‐tube SPME. The morphology and chemical structure of the monolithic phase were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. The proposed method presented linear range from the lower limits of quantification 0.6 and 0.8 to 10 ng mL−1. Excluding the lower limits of quantification values, the analytical validation showed precision with the coefficient of variation values lower than 13.1%, and accuracy with relative standard deviation lower than 13.5%. The in‐tube SPME coupled to UHPLC–MS/MS method was successfully applied to determine amyloid beta peptides in CSF samples from AD patients.