Q41 · CSIR NET Chemistry, December 2013
Paper: CSIR NET December 2013 · Subject: Inorganic Chemistry · Chapter: Analytical Chemistry · Topic: Analytical Chemistry – General · Marks: 2 · Difficulty: Medium
In the atomic absorption spectroscopic estimation of Fe(III) using $\mathrm{O}_{2} / \mathrm{H}_{2}$ flame, the absorbance decreases with the addition of
(a)$\mathrm{CO}_{3}^{2+}$
(b)$\mathrm{SO}_{4}^{2-}$
(c)EDTA
(d)$\mathrm{Cl}^{-}$
Answer
Answer: B ✓ checked by 4AB · confidence medium
Explanation
Sulfate (like phosphate) forms thermally stable, poorly atomised iron salts in the cooler O₂/H₂ flame — a chemical interference that lowers the absorbance. EDTA and Cl⁻ give volatile species and do not suppress it.
Study loop for Analytical Chemistry