Sergey Bylikin, Gary Horner and, Brian Murphy Solutions for Chapter: Medicinal Chemistry, Exercise 9: Questions

Anabolic steroids are used by some athletes as performance-enhancing substances. Explain how steroids and other illegal drugs can be detected in the human body chromatography and mass spectrometry?

Ethanol is sufficiently volatile to pass into the lungs from the bloodstream. The roadside breathalyzer uses potassium dichromate ($\mathrm{VI}$), which reacts with ethanol present in the breath. Deduce the oxidation and reduction half-equations that occur in the breathalyzer.   

State, and explain, in terms of electron transfer, and oxidation number change, whether chromium in potassium dichromate ($\mathrm{VI}$) is oxidised or reduced?

Explain how the concentration of ethanol can be determined by the use of a fuel cell and IR spectroscopy?

The presence of ethanol in the breath can be detected by blowing into a "bag" through a tube with acidified potassium dichromate ($\mathrm{VI}$). The half-equation for the dichromate reaction is ${\mathrm{Cr}}_2{{\mathrm{O}}_7}^{2-}\left(\mathrm{aq}\right)+14{\mathrm{H}}^{+}\left(\mathrm{aq}\right)+6{\mathrm{e}}^{-}\stackrel{ }{\to }2{\mathrm{Cr}}^{+}\left(\mathrm{aq}\right)+7{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$. Describe the colour change observed when the dichromate ion reacts with the ethanol. 

The presence of ethanol in the breath can be detected by blowing into a "bag" through a tube with acidified potassium dichromate ($\mathrm{VI}$). State the name of the organic product formed during the reaction.

In order to quantify exactly how much ethanol is present in the blood, a person may be required to give a blood sample or may be asked to blow into an intoximeter. Explain the chemistry behind the techniques for determining the ethanol content in a blood sample, and by using an intoximeter.

Modern drug detection techniques increase the chances of people being caught using illegal substances. Discuss how changes in technology influence our ethical choices?