An automated method of evaluating a collected fluid sample includes: filling a sample cavity with the collected fluid sample； adding a buffer solution； separating the collected fluid sample into a first portion and a second portion； mixing the second portion with tagged antibodies； removing leftover tagged antibodies； and measuring a difference between the first portion and the second portion. A sample collection and testing device includes: a reference cavity comprising a reference fluid sample； a test cavity comprising a test fluid sample； a reference measurement element associated with the reference cavity； and a test measurement element associated with the test cavity. A method of evaluating a collected fluid sample including: separating the sample； pumping a first portion to a first measurement cavity； adding a solution to a second portion and pumping the mixture to a second measurement cavity； and measuring a charge difference between the first and second measurement cavities.
