What is the purpose of blank samples in QC and calibration runs?

What is the purpose of blank samples in QC and calibration runs?

• A. To calibrate instrument using known concentration.
• B. To increase sample throughput.
• C. To monitor contamination, carryover, and baseline noise, ensuring assay specificity.
• D. To provide internal standard.

Answer: (C)

Blank samples establish the instrument’s baseline response and reveal background signals not due to the analyte. In QC and calibration runs, they help detect contamination, carryover from previous samples, and baseline or electronic noise. This is crucial for assay specificity: any true analyte signal in real samples should rise above what appears in the blank. If the blank shows a signal, it signals potential background artifacts that could cause false positives, prompting investigation or adjustments to prevent interference. Blank runs are not used to calibrate with a known concentration—that’s what calibration standards are for. They also don’t provide an internal standard, which is a separate compound added to each sample to correct for variability. And their purpose isn’t to increase throughput; they serve to verify that background signals won’t compromise results.

Blank samples establish the instrument’s baseline response and reveal background signals not due to the analyte. In QC and calibration runs, they help detect contamination, carryover from previous samples, and baseline or electronic noise. This is crucial for assay specificity: any true analyte signal in real samples should rise above what appears in the blank. If the blank shows a signal, it signals potential background artifacts that could cause false positives, prompting investigation or adjustments to prevent interference. Blank runs are not used to calibrate with a known concentration—that’s what calibration standards are for. They also don’t provide an internal standard, which is a separate compound added to each sample to correct for variability. And their purpose isn’t to increase throughput; they serve to verify that background signals won’t compromise results.