Purity in chromatographic separation fractions is calculated as the amount of solute eluted divided by the amount of impurity eluted. The correct answer is option B.

Question Breakdown

This MCQ assesses understanding of purity determination in collected fractions (t1 to t2) from chromatography, common in analytical biochemistry and GATE Life Sciences.

Option Analysis

• A. Amount of solute eluted − amount of impurity eluted: Incorrect. Subtraction gives net amount, not purity percentage or ratio.

• B. Amount of solute eluted / amount of impurity eluted: Correct. Purity is the ratio of target solute to impurities (often expressed as % when normalized to total).

• C. Amount of solute eluted + amount of impurity eluted: Incorrect. Addition yields total eluted material, not purity.

• D. Amount of solvent eluted / amount of impurity eluted: Incorrect. Solvent (mobile phase) is not a measure of solute purity.

Introduction
The purity of a solute collected between two times t1 and t2 during chromatographic separation is amount of solute eluted / amount of impurity eluted. This ratio-based calculation ensures accurate assessment of fraction quality in techniques like HPLC, vital for pharma analysis and GATE Life Sciences prep.

Purity Calculation Explained

In chromatography, fractions collected from t1 to t2 contain separated peaks. Purity = (solute peak area/concentration) / (impurity peak area/concentration), often via area normalization (% purity = solute area / total area × 100).

Peak purity analysis checks for co-elution using UV spectra or MS across the peak.

Practical Steps

• Integrate peak areas from chromatogram between t1-t2.

• Apply response factors if needed.

• Report as % purity for compliance.