Simultaneous determination of nine trace concentration angiotensin peptides in human serum using ultra high performance liquid chromatography with tandem mass spectrometry with sephadex LH‐20 gel solid‐phase extraction

The renin–angiotensin system is a highly complex enzymatic system consisting of multiple peptide hormones, enzymes, and receptors. Here, an assay to simultaneously quantify eight angiotensin peptides and bradykinin in human serum was developed and validated, using ultra high performance liquid chromatography coupled with tandem mass spectrometry. A pre‐concentration method of Sephadex LH‐20 gel solid‐phase extraction was first applied for analysis of angiotensin peptides from serum sample. The triple quadrupole mass spectrometer was operated in the positive ion mode and multiple reaction monitoring was used for drug quantification. The analytical time was within 5 min, much raising the analysis efficiency. Limits of detection ranged from 0.9 to 1.3 pg/mL, and displayed the same level of sensitivity compared with radioimmunoassay. The method was successfully applied to 22 healthy human serum samples, giving the concentrations of angiotensin I, angiotensin II, angiotensin III, angiotensin IV, angiotensin 1–9, angiotensin 1–7, angiotensin 1–5, Asn1,Val5‐Angiotensin II, and bradykinin for reference. This novel metabolic profile study of vasoactive peptides based on gel solid‐phase extraction concentration provided not only an accurate quantitative assay of the serum concentrations, but also a promising methodology for evaluating the diagnostic values of the various peptides.