Maggie O’Brien
Chem 411
11/17/11
Measuring Fluorescence from Quinine in Tonic Water
Calibration Curve:
y = 0.2679x + 0.0143
R² = 0.9925
0.08
0.07
0.06
y = Is+x*V/Vo
0.05
0.04
0.03
0.02
0.01
0
-0.1
-0.05
0
0.05
0.1
x = Si*Vs/Vo
0.15
0.2
0.25
Emission Spectrum:
0.07
Fluorescence 405 nm (Rel)
Abstract:
The amount of quinine in Canada Dry tonic water will be
quantified using a Spectrovis plus Spectrophotometer and
Fluorometer. Quinine was the first effective malaria
treatment. Today, it is a treatment for lupus and arthritis and is
used as a cutting agent for cocaine and heroin. Conjugated
quinine displays a blue fluorescence, which will be measured
at 459.9 nm using multiple standard addition meaning the
sample will be spiked with 50 uL of 18% (w/v) quinine
sulfate before each additional fluorescence measurement. The
spectra should gain better resolution and show greater
emission as the quinine concentration increases with each
additional spike, and the amount of quinine should fall
between 40-70 ppm.
0.06
0.05
0.04
0.03
0.02
0.01
385
485
585
Wavelength (nm)
685
Results and Conclusion:
From the completion of 8 standard additions of 50 uL spikes of
18% (w/v) quinine sulfate to the 2 mL sample of tonic water,
the amount of quinine was determined to be 53.37 ppm. This
value was calculated using a least squares spreadsheet on
Excel. It seems reasonable because it falls within the 40-70
ppm range given by Classroom Demonstrations of Concepts in
Molecular Fluorescence by Blitz, Sheeran, and Becker. As seen
in the emission spectrum, the maximum wavelength was 459.9
nm. From the emission spectrum, it can also be seen that the
resolution improved upon additional spikes and greater
emission was shown as the concentration of quinine increased.
This matches hypotheses made prior to the experiment.