A forensic laboratory must determine whether a confiscated liquid sample contains the…
CHEMISTRY · Multi-part · AP · Chemistry · Properties of Substances and Mixtures · Properties of Substances and Mixtures
Problem
A forensic laboratory must determine whether a confiscated liquid sample contains the illegal dye Sudan I, whose chromophore is highly conjugated. The lab owns the following equipment:
• A benchtop IR spectrometer (mid-IR region)
• A portable UV-Vis spectrometer (200–800 nm)
• A high-resolution microwave spectrometer (12–18 GHz)
Because of strict time constraints, the laboratory manager allows the analyst to use exactly one of the three instruments and no others.
Respond to the prompts below.
(a) Select the instrument that provides the most direct and definitive evidence for the presence of Sudan I in the liquid sample.
(b) Justify your selection by discussing the nature of the chromophore in Sudan I and how that structural feature determines the molecule’s interaction with the chosen region of the electromagnetic spectrum.
(c) Describe one characteristic spectral feature you would expect Sudan I to exhibit with the chosen technique, and explain how that feature distinguishes Sudan I from typical non-conjugated organic impurities.