Determination of Quinine in Tonic Water

Experiment 2

Title: Determination of Quinine in Tonic Water

Objective:
To Determine the Concentration of Quinine Hydrochloride in Sample (Schweppers) given, by plotting a Calibration Curve of Fluorescent Intensity against Concentration of Quinine Hydrochloride in ppm, after Fluorescence Intensity of a series of Standard Solution prepared and the Sample solution by Fluorescence Spectrometer.

Data:
Brand name of tonic water sample: Schweppes
Dilution factor = 1000

Concentration of quinine standard (ppm)
Fluorescence intensity (mean)
Blank
2.945
0.02
78.40
0.04
187.8
0.06
223.4
0.08
295.7
0.10
373.6
Original tonic water sample
2635
Diluted tonic water sample
273.3

Data Treatment:
1. Plot the calibration curve with fluorescent intensity against concentration of quinine hydrochloride in ppm (from Blank to 0.1 ppm).

By the Least Square Method, it is assumed that the relationship between x and y is linear, as below equation, y = mx + b m is the slope of equation and y is the y-intercept of equation

b = , m =

Solution
Concentration of Quinine Standard (ppm) (xi)
Fluorescence Intensity
(Mean) (yi)
(xi)2
xi yi
Blank
0.00
2.945
0.0000
0
0.02
0.02
78.4
0.0004
1.568
0.04
0.04
187.8
0.0016
7.512
0.06
0.06
223.4
0.0036
13.404
0.08
0.08
295.7
0.0064
23.656
0.10
0.10
373.6
0.0100
37.360
Sum of Column
0.30
1161.845
0.0220
83.500

m = = =3629.68 b = = = 12.157

By Least Square method, it was found that the relationship between Fluorescent Intensity against Concentration of Quinine Hydrochloride (in ppm) would be described as a linear equation of y = 3629.7x – 12.157 with R² = 0.9877

2. Report the brand name and the amount of quinine hydrochloride in ppm in the sample from the calibration curve.
The brand name of the sample: Schweppes

The corrected fluorescence intensity of sample = 14.542 y = 3629.7x – 12.157
273.3 = 3629.7x – 12.157 x =