Basically, there are two types of technique used for handling liquid using micropipette. One of them is the forward pipetting and another one is reverse pipetting. The usage of these techniques varies with the type of liquid that will be handled. Forward pipetting normally use for pipetting the aqueous solution, acid and alkali, volatile compound and also radioactive compound. Forward pipetting has higher accuracy compare to reverse pipetting and it operates by aspirate the entire volume into the pipette. Firstly, we need to set up the desire volume that we want. Depress the button until the first stop, place the tip just 1 cm below the water surface and release the button slowly to draw the solution. After that, dispense the liquid by pressing the button to first stop and continue to second stop. It will empty the tip as it removes excess solution inside the tip.
Reverse pipetting normally used to transfer high viscosity solution and solution that foams easily including solution containing detergents. First, fix up the volume that to be transferred. Press the button until second stop, and then place the tips 1 cm below the solution and slowly release the button to draw the solution. Withdraw the solution by pressing the button until first stop. There will be a remaining of solutions inside the tip and discard it with the tips.
Briefly explain how you could improve the accuracy and precision of a micropipette.
In order to improve accuracy of micropipette, we should pre-wet the tips at least three times before start the pipetting as it will increase the humidity and prevent the evaporation of the sample. Failing to pre wet before the pipetting will cause least volume of solution in initial samples. When pipetting, we need to hold the pipette in upright position when aspirate the liquid especially for small volumes. It is because to prevent more liquid aspirated into the tip from