A sensitive and quantitative element-tagged immunoassay with ICPMS detection

We report a set of novel immunoassays in which proteins of interest can be detected using specific element-tagged antibodies. These immunoassays are directly coupled with an inductively coupled plasma mass spectrometer (ICPMS) to quantify the elemental (in this work, metal) component of the reacted tagged antibodies. It is demonstrated that these methods can detect levels of target proteins as low as 0.1 -0.5 ng/mL and yield a linear response to protein concentration over 3 orders of magnitude.