In bichromatic analysis, which statement is false?

In bichromatic analysis, which statement is false?

• A. Absorbance is measured at the spectral absorbance peak for a blank and the sample using the same wavelength.
• B. Eliminates background interferences
• C. Sample concentration determined from difference in two measured absorbances
• D. Functions as a reference blank for each sample

Answer: (A)

In bichromatic analysis the signal from the analyte is isolated by using two wavelengths: one at the analytical wavelength where the analyte absorbs, and a second at a reference wavelength where the analyte’s absorption is minimal. The background—solvent, turbidity, stray light, and other interferences—affects both wavelengths similarly, so subtracting the reference measurement from the analytical measurement cancels much of this background. The resulting difference is proportional to the analyte’s concentration through Beer's law, and the reference wavelength effectively serves as a per-sample blank to correct for any background present. Therefore, the statement that absorbance is measured at the spectral absorbance peak for a blank and the sample using the same wavelength is false, because bichromatic analysis relies on two different wavelengths to separate the true signal from background. The other points align with how bichromatic analysis reduces interferences, uses the difference of two absorbances to determine concentration, and treats the reference measurement as a blank for each sample.

In bichromatic analysis the signal from the analyte is isolated by using two wavelengths: one at the analytical wavelength where the analyte absorbs, and a second at a reference wavelength where the analyte’s absorption is minimal. The background—solvent, turbidity, stray light, and other interferences—affects both wavelengths similarly, so subtracting the reference measurement from the analytical measurement cancels much of this background. The resulting difference is proportional to the analyte’s concentration through Beer's law, and the reference wavelength effectively serves as a per-sample blank to correct for any background present.

Therefore, the statement that absorbance is measured at the spectral absorbance peak for a blank and the sample using the same wavelength is false, because bichromatic analysis relies on two different wavelengths to separate the true signal from background. The other points align with how bichromatic analysis reduces interferences, uses the difference of two absorbances to determine concentration, and treats the reference measurement as a blank for each sample.