How To: Mix gradients with a gradient mixer in the lab

The Department of Biological Sciences at the University of Alberta brings you this video tutorial specifically relevant to your student laboratory courses, specifically microbiology. If you're a student at any school of biology, this information will be helpful for learning how to mix gradients with a gradient mixer in the lab.

Part A: A mixing chamber is attached to a rubber tube whose outlet is clamped to the bottom of a test tube. Pipette 6.2 mL of dilute solution into the M chamber of the mixer while the valve is closed.

Part B: Slowly open the valve to allow the solution to fill the connecting line between the two chambers. There should be no bubbles in this line.

Part C: Add 5.0 mL of concentrated solution to the R chamber. Note that we colored our denser solution with red dye to make the gradient more visible.

Part D: Position the automatic mixer so the bottom of the stirring rod is about 3 mm from the bottom of the m chamber. Begin mixing, avoid violent agitation but with sufficient vigor that good mixing will occur. Open the valve and open the stopper on the tubing. Check to see if the liquid flowing through the m chamber is being mixed.