Systems and methods for performing source separation are provided. An automatic analyzer can set hold and discard conditions and manage the elapsed time after a diluted sample is pipetted. The apparatus may have a threshold verifier capable of verifying that the threshold voltage is set within an acceptable voltage range of a target threshold voltage. To reduce false positives, other additional indicators, such as speed of movement, and or visual features of the person, can be used to further narrow a person suspected of wearing wires.