Testing Allelopathy Methods
Hydroponic Set Up
Why a hydroponic set up?
Hydroponic systems allow you to grow plants in a water medium instead of soil.
Because soil contains a lot of non-plant activity, it can be hard to trace any specific chemical back to its original source. Hydroponics provide a simplier picture, as there is better control over the environment.
For this experiment, we set up three hydroponic systems that contained a water resevoir, circulator pump, and trays that housed the plants. All three set up were identical and only varied in what was placed in the trays.
Using Activated Carbon
In this project, we absorbed chemicals present in the water by using activated carbon. Activated carbon is a type of carbon that contains small pores, that allow for absorpotion of chemicals in compounds.
We took samples of the chemicals in the water at day 14, 28, and 42 by placing activated carbon into mesh baggies inline with the circulation pump of the hydroponics system. The activated carbon was allowed to soak up the chemicals for 5 days before we took it back to the lab for processesing.
Processing the Carbon
We took the carbon back to the lab where we allowed it to desorb in a 50/50 mix of sodium hydroxide and methanol for 24 hours.
Organic compounds in the resulting solution were extracted using liquid-liquid extraction with diethyl ether. The result was concentrated using liquid evaporation.
Analyzing the Sample
The sample was tested using Gas Chromotography-Mass Spectroscopy (GC-MS). GC-MS is an analytical chemistry method that identifies chemicals within a solution. The GC-MS evaporates the solution onto a coil inside the machine. Then, the GC-MS slowly increases the temperature.
Because different chemicals vaporize at different temperatures, the GC-MS can identify the chemicals the solution contains based on the points where it sees vaporization points. The result is a chromotagram (to the left), which shows peak points where every chemical vaporized.