To begin we did a very simple experiment that allows to measure the absorbance of solutions containing different known concentrations of patent blue V (E131), a blue pigment that is used in various blue candies.
The result is rather good knowing that the solutions were simply prepared by adding various volumes (0 to 2 mL) of a concentrated solution with a 1mL seringe to 100mL of water. Not the mst accurate method.
You may check the following protocols
In order to determine if the spectrophotometer is able to measure the difference of UV absorbance in a fluorescence quenching situation, we used fluorescein and potassium iodide (KI) as a quencher.
To do it, we started with a solution of KI 0.01M that was diluted to obtain solutions at 0.005M, 0.001M, 0.0005M, 0.0001M. Then from each solution we picked 3 drops and put them in a tank full of florescein (concentration?!).
Here are the results:
If you want to check all our measures, please click on the following link:
In order to detect mercury, carbon quantum dots (CQDs) can be used. They are small particles of carbon (which can be homemade) that become fluorescent in presence of UV light. The interesting part of this application is that the CQDs react differently with mercury, and that this difference can be measured using the simple-spectrophotometer.
– 14g of sucrose or fructose
– 40ml of lemon juice or 40 ml of water and 20 drops of HCl 18%
– 0.5 g of sodium bicarbonate
– a hot plate
– a magnetic stirrer
– an aluminum foil
– a beaker
– a spatula
To use the CQDs, you will have to dilute them (for more precise quantities, please wait, work in progress…!)
Using the simple-spectrophotometer, we tested for the reaction of CQDs when exposed to UV light, while the particles were diluted in water. We used water as blank, and test for different concentration of CQDs (1, 3 or 5 drops per tank). We obtained those results:
Plotting the absorbance of the samples, we obtain the following graph:
The R squared is equal to 0.958.
You can find all the values here:
The color of the red cabbage highly depends on the pH of a solution. We are trying to determine if it is possible to create a model with the simple-spectrophotometer to allow the users to estimate easily the pH of their solution.
– 500g of red cabbage
We are trying to create a precise procedure to use it, for the moment you can see the results of our attempts: