\"Fraction 2\" and 3mL of distillate. (the width has already been multiplied by
ID: 481690 • Letter: #
Question
"Fraction 2" and 3mL of distillate. (the width has already been multiplied by 1/2 as directed)
Peak A: Height 35mm and the width 1.5mm. Peak area = 52.5mm2
Peak B: Height 14.5mm and the width 2.5mm2. Peak area = 36.25mm2
"Fraction 1" and 3mL of distillate
Peak A is on the left with width and height measurements of as follows
Height 36mm , Width 1.25mm. Total peak area is equal to height multiplied by the width. Peak A area = 45mm2
Peak B: width 2mm and height 4mm. Peak B area = 8mm2
0.5h 95% Ethanol Student sample Diagram of peak area analysis of fermentation Gas chromatography can be used qualitatively by comparing retention times. It can be used quantitatively by using an integrator, which is limited to more expensive instruments. One manual method involves calculating the areas of the peaks using the height of the peak from the baseline (measured in millimeters) multiplied by the width at half height. The drawback to this method lies in the symmetry of the peaks. You are fortunate to have a modern instrument with an integrator, so the area under each peak will be reported in the GC trace. The equations below will help you calculate the total volume of ethanol in your distillate from these areas. Area of EtOH peak EtOH x 100 in fraction Area of EtOH peak. Area of H2O peak Volume of EtOH distilled fraction 1 x ((%EtOH in fraction 1)/100) V. 2 ((%EtOH in fraction 2)/100) fraction Total EtOH in 100 mL of fermentation mixture 2 x Volume of EtOH distilledExplanation / Answer
The peak with greater intensity contains the analyte which in this case is ethanol.
So for fraction 2, Ethanol peak area (A1) = 52.5 mm2
Water peak area (A2) = 36.25 mm2
% Ethanol = 100*A1/(A1 + A2) = 59.1%
For Fraction 1, Ethanol peak area (A1) = 45 mm2
Water peak area (A2) =8mm2
Again % Ethanol = 84.9 %
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