Question

Would atomic emission spectroscopy be a useful technique for determining the oxidation state of arsenic in a water sample? Why or why not? (Bonus, what would an analyst have to do to determine oxidation state? (otherwise referred to as "speciation"))

List two reasons why the excitation bandwidth using a hollow cathode lamp is much narrower than the emission bandwidth for atomic spectroscopy? Use an equation in your answer (hint, think Doppler).

Answer 1

Arsenic species are unstable and can change oxidation state in sample handling. Atomic emission spectroscopy is a useful technique used for the measure the oxidation state of arsenic in water sample. In this technique the molecule is get excited by light or heat and go in higher oxidation state from lower oxidation state. When it come back from higher to lower ocioxidat state the energy release in the form of radiation. These radiation are emitted in the form of photon. And the photons has a wavelength which is recorded in atomic spectrum known as atomic emission spectrum. It is used as fingerprint for every element. For example Arsenic(3) and Arsenic (5) oxidation state are measured by this technique.

The other techniques used for speciation are HPLC, INDUCTIVE COUPLED MASS SPECTROSCOPY, HYDRIDE GENERATION MASS SPECTROSCOPY. These are the best method for arsenic speciation.