What is a Blank Spike?

• A. A sample with no analyte added.
• B. Measured aliquots of known concentrations added to deionized water and used to evaluate accuracy.
• C. A matrix spike with added analytes.
• D. An environmental sample through all steps.

Answer: (B)

A blank spike tests how well a method can recover a known amount of analyte in a truly clean matrix. It uses a blank sample—like deionized water—with measured aliquots of known concentrations added. By analyzing this spiked blank, you measure the accuracy and recovery of the method without interference from any native sample matrix. This approach directly isolates the analytical performance, showing how close the measured values come to what was added.

The other scenarios describe a true blank with no analyte, a matrix spike where the analyte is added to a real sample, or simply processing an environmental sample, which do not isolate accuracy in a clean blank matrix.