Introduction to Forensic Science Practice Test 2026 – Your Complete Guide to Exam Success!

In QA/QC, controls serve three distinct checks: contamination, detection capability, and recovery accuracy. Blank controls contain no analyte, so they reveal any contamination or background signal in the assay. Positive controls contain a known target amount and confirm that the assay can detect the target under current conditions; they show that the system is working properly. Spike-in controls add a known quantity of the target into a sample, allowing you to assess recovery and accuracy through the processing and measurement steps, including how the matrix might affect recovery.

The described combination—blank controls for contamination, positive controls for detection capability, and spike-in samples for recovery and accuracy—best captures the full set of roles for these QA/QC controls. The other statements omit one or more of these essential functions or misstate the purpose of spike controls.