Negative Control (Blank)
Definition
A sample known to contain no target analyte, processed alongside casework samples. Confirms that background contamination is not producing false signals in the batch.
- Field
- Analytical chemistry and toxicology quality control
- Contents
- Sample known to contain no target analyte
- Run alongside
- Casework samples in the same batch
- Purpose
- Rules out background contamination as a false signal
Common questions
What does a positive signal in a negative control blank mean for the rest of the batch?+
It indicates the analytical system itself, such as glassware, reagents, or instrument carryover, introduced a signal that could be mistaken for the target analyte, so any positive result in the batch's actual case samples becomes suspect until the source of contamination is identified and the batch is rerun clean.
Is a negative control the same thing as a calibration blank used to zero an instrument?+
No. A calibration blank is used to set the instrument's zero point during calibration, while a negative control blank is processed through the entire sample preparation workflow alongside real samples specifically to catch contamination introduced during handling, not just instrument drift.
Related terms
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- Positive Control
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