Basics of Laboratory Research and Experimental Design
Experimental Design
An important part of your experiment is to envision how it will be accomplished. Before you even begin setting up an experiment, you should understand what you want to measure and why you are measuring it. Include details on the wiki and update your Detailed Task List.
You should sketch out how you will set up the experiment. If you have an existing experiment, think about what if anything needs to be modified.
After you have an idea of what sort of experiment you will run and how you will set it up, you should utilize Process Controller to automate the experiment. Details of how to use ProCoDA Software can be found on the wiki.
Equipment in the Laboratory
Tubing and Tubing Connections
There exist two types of tubing that we utilize in conducting experiments: soft peristaltic (easily bendable) and hard tubing.
Peristaltic pump tubing is a special formulation (we use a formulation called PharMed) designed to be very flexible. The manufacturer labels the tubing arbitrarily with size designations of 13, 14, 16, 17, and 18. Peristaltic pump tubing can be connected to other types of tubing using a barbed fitting. Only put peristaltic tubing on the barb. Note: If you put inflexible tubing on a barbed connector, you may never get it off again.
Simple rules to remember:
- soft tubing for peristaltic pumps with a barbed connector.
- hard tubing goes with a push-to-connect connector.
- Other flexible tubing (tygon or PVC formulation) is useful in creating coils for flocculators and can be put into a push-to-connect connector.
Making Tubing Connections
When you make a connection utilizing a push-to-connect connector, ensure that you push the tube is fully engaged in the connector. The tube needs to slide inside of an o'ring seal in the connector. You should feel a pop, when the tube slides inside the o'ring.
With peristaltic pump tubing, ensure that the tubing tightly fits over the barbed part.
Exercise in Experimental Design and Set-Up
Here is a sample exercise that should help to set up an experiment in lab. In a group or individually sketch out an experimental schematic of a mixing process to blend to chemicals.
On one end you want to have a chemical stock tank in a one liter bottle hooked up to a computer controlled peristaltic pump. The pump will meter in the chemical at a set rate to a 4 L tank that has a pressure sensor set up at the bottom to record the height of water. For part of the experiment you want to meter in the chemical (without drainage), however for another part of the experiment you do not want to meter in the chemical. For another part of the experiment you want to be able to drain the tank while adding in more chemical.
In your drawing, you can indicate a peristaltic pump as a circle inside of a square, a chemical stock tank as a bottle, a solenoid valve with an X and tubing as a straight line. Try to draw the pressure sensor as it appears.
Click here to see how closely your schematic matches this one.
In the drawing label important experimental parameters such as concentration of chemical stock, flowrate of chemical stock.