Oxidized lipid detection

A method of extracting oxidised lipids from a lipid solution, the method comprising

• (a) a derivatisation step, comprising:
• (i) a reductive amination of aldehydic oxidised lipids present in the lipid solution, comprising
• contacting the lipid solution with a derivatisation agent selected from 2-aminoanthranilic acid (2AA), 4-aminoanthranilic acid (4AA), 3-(4-aminophenyl)-propionic acid (4APA) and 6-aminocaproic acid (6ACA), such that the aldehydic oxidised lipids present in the lipid solution are derivatised to include a carboxy group;
• or
• (ii) a hydrazone formation with aldehydic oxidised lipids and/or α,β-unsaturated oxidised lipids present in the lipid solution, comprising
• contacting the lipid solution with a derivatisation agent that is a compound according to formula (I):
• or a salt, solvate or hydrate thereof
• wherein:
• X represents a carboxy group
• each L independently represents a single bond or linker group
• n is an integer from 0 to 4, and
• A represents an optionally substituted heteroaryl or aryl group,
• such that the aldehydic oxidised lipids and/or α,β-unsaturated oxidised lipids present in the lipid solution are derivatised to include a carboxy group;
• and
• (b) an oxidised lipid capture step, in which nanoparticles are contacted with the lipid solution, wherein the nanoparticles capture carboxy group containing oxidised lipids.