Download Proper Pipetting SOP

CALIFORNIA STATE POLYTECHNIC UNIVERSITY, POMONA
Environmental Health & Safety
STANDARD OPERATING PROCEDURE
Safe Work Practices: Proper Pipetting SOP
GENERAL INFORMATION:
In working with materials classified as a Biohazard, certain risks may be present which
depend on the agent being used. A particular concern when working with Biohazards is the
generation of aerosols, the act of dispersing a material into the air. This can be caused
deliberately or inadvertently, the latter being of critical concern in order to limit accidental
exposure while working. Infectious agents that possess a route of transmission through
inhalation are the most dangerous as others are less likely to create a hazard in aerosol
form however, safe work practices to reduce the generation of aerosols is a good and
prudent industry practice. While there are many opportunities to generate aerosols using
high-speed equipment, this guidance is focused specifically on pipetting and transfer of
liquids in small volumes.
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All work involving biohazards, infectious or disease causing agents should
ALWAYS be done inside a biosafety cabinet with a proper rating and current
certification. Please refer to the Biosafety Cabinet Program and respective SOP’s for
proper use and materials handling inside a biosafety cabinet.
NEVER PIPETTE BY MOUTH (MOUTH PIPETTE). Under no circumstances is this
ever an approved or accepted practice regardless of the material being used.
Use “Mark to Mark” pipettes that do not require forcible expulsion of a final drop
from the pipette. If “Mark to Mark” pipettes are not available, consider pipetting “by
difference” to achieve the volume needed without creating an aerosol.
Never blow the last drop from a pipette as this can create significant aerosol and
inhalation risks.
Always use filtered pipettes and pipette tips to protect equipment from
contamination
Never mix liquids or solutions by suction and expulsion from the pipette from
contamination with aerosols.
If possible, try to work immediately above a plastic-backed absorbent pad to
minimize the formation of aerosols.
When transferring liquids into a container, always dispense liquids against the
sidewall and low to the liquid surface to prevent splashes and formation of
aerosols.
Never drop liquids from a height to a surface or to another liquid.
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If using a vacuum source for aspiration of liquids, protect the vacuum source from
any possible contamination by using a collection and overflow flask, protected by a
HEPA or hydrophobic filter to prevent the formation of aerosols at the vacuum
source and causing contamination.
Avoid using glass Pasteur pipettes which creates puncture risks. Biohazards should
always utilize plastic aspiration pipettes.
Collect used pipettes within the biosafety cabinet inside a horizontal collection tray
that allows the pipette to be completely immersed in a disinfectant.
To decontaminate a pipette, draw disinfectant into the pipette in a vertical
orientation and dispense gently in the horizontal collection tray. A minimum of 10
minutes in a disinfectant is required to be considered inactivated.
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