Accurate and sensitive measurement of aldosterone in plasma or serum is a key parameter for assessment of primary aldosteronism (PA) or other adrenal diseases. Immunoassays suffer from cross-reactivity with metabolites while GC-MS methods require extensive sample preparation and derivatization. High-sensitivity analysis using LCMS/MS, while being usually more specific and simple, is also challenging because of low ionization yield and may require high sample volume. Micro-flow electrospray is a good compromise between ionization efficiency improvement and ease-of-use, compared to nano-electrospray.
Here we present a method to quantify aldosterone in serum samples by micro-flow LC/MS/MS to reach low concentrations using a limited volume of sample.