Bradykinin is a nine amino acid peptide that causes blood vessel dilation, and therefore a decrease in blood pressure.The ability to measure changes of this peptide hormone with high sensitivity, selectivity and accuracy, as a function of disease progression or drug treatment is thus highly advantageous.Accurate quantification in plasma is particularly challenging because it is present in low pg/ml levels, rapidly metabolized, and also artificially produced during blood sampling and sample preparation via proteolytic processes.