If blanking cannot be performed, which approach is used?

• A. Ultracentrifugation
• B. Dual-Wavelength technique
• C. Two-beam correction
• D. Baseline subtraction

Answer: (A)

When you can’t perform a blank, removing interference by a physical separation step is effective. Ultracentrifugation spins the sample at very high speeds to pellet unwanted components like proteins, lipids, cells, or aggregates, leaving a clear supernatant containing the analyte of interest. Analyzing this clarified sample reduces background absorbance or scattering that would contaminate the measurement, effectively compensating for the lack of a blank.

Other correction methods rely on measuring background signals or reference paths, which assume you have a usable blank or stable background. Without blanking, those corrections become unreliable, so the separation step is the practical approach to obtain an accurate result.