What is the detection limit of a luminometer?

• A. sub-picomolar (<10^-12)
• B. nanomolar (10^-9)
• C. picomolar (10^-12)
• D. femtomolar (10^-15)

Answer: (A)

The detection limit is the smallest amount of analyte that can be reliably distinguished from background in a luminometric assay. Luminometers detect light produced by chemiluminescent reactions, and with very low background and strong signal amplification, they can sense extremely small concentrations. Saying sub-picomolar (<10^-12 M) reflects this high sensitivity, indicating the limit is below 1 pM. The other options describe higher concentrations (nanomolar or picomolar) and don’t capture how low the detectable level can be with modern luminescence, whereas sub-picomolar best expresses the instrument’s ability to detect very small amounts.