The influence of sample collection methodology and sample preprocessing on the blood metabolic profile.

Aim: Blood serum and plasma have intrinsic differences in their composition and the preprocessing, such as clotting temperature in serum, and storage at room temperature may have further effect on metabolite concentrations.

Methods: The influence of sampling preprocessing on the metabolic profiles in serum and different types of plasma was investigated using liquid chromatography and comprehensive 2D gas chromatography coupled to a mass spectrometer.

Results: The profiles of polar metabolites were significantly dependent on the type of the sample, while lipid profiles were similar in serum and different types of plasma. Extended storage of plasma at room temperature resulted in degradation of lipids already after 1 day. Serum clotting at room temperature generally resulted in higher metabolite concentration compared with serum clotting on ice.