Use of pipettes and pipetting aids 1. a pipetting aid must always be used. Pipetting by mouth must be prohibited. 2. All pipettes should have cotton plugs to reduce contamination of pipetting devices. 3. Air should never be blown through a liquid containing infectious agents 4. Infectious materials should not be mixed by alternate suction and expulsion throughUse of pipettes and pipetting aids 1. A pipetting aid must always be used. Pipetting by mouth must be prohibited. 2. All pipettes should have cotton plugs to reduce contamination of pipetting devices. 3. Air should never be blown through a liquid containing infectious agents. 4. Infectious materials should not be mixed by alternate suction and expulsion through