Caring of Plastic Labware
Plastic
labware is a crucial ingredient of any laboratory. So it is imperative that
all the plastic labware is properly cleaned and cared for to get the right
result. In this page different aspects of caring as well as cleaning of
plasticware has been provided to guide the users to accurate experiment
results.
Effect
of Chemicals on Plastic Labware
Certain types of chemicals like oils, detergents, lubricants,pure water and
surface additives in presence of tensile stress can result in cracking of
the plastic ware. Extended exposure to strong oxidising agents are also
known to cause embrittlement and failure. A Chemical affects the strength,
flexibility, appearance, dimensions as well as weight of plastic labware.
The intensity depends upon.
Length of
exposure |
Temperature
|
Concentration
|
Effect of Heat on Plastic Labware
Plastic labware should never be allowed to come in direct contact with a
flame or put on a hotplate surface.
General
Cleaning
For most of the general applications plastics if washed with a mild
detergent is enough. Following the washing, rinsing with tap water, and a
final rinse with distilled water is to be undertaken. Generally plastics,
especially the polyolefins (polypropylene,PPCO, PMP, LDPE, and HDPE) are
associated with a nonwetting surface. This makes them resist attack and easy
to clean. However a note of caution for plastic labware.
- Never use abrasive cleaners or scouring pads
- Resist using strong alkaline cleaning agents for polycarbonate (PC)
labware
Cleaning
with Laboratory Washing Machine
Laboratory washing machine works well with with almost all resins except a
few. Resins like acrylic, polystyrene (PS), and LDPE are not suited to
washing machines due to temperature limitations. Poly carbonate also gets
weakened if washed repeatedly in dishwashers. For polystyrene labware a
detergent which is mild, nonabrasive, pH neutral, non-caustic is the best.
agents. Following guidelines are to be followed for cleaning of lab
plasticware in a washing machine.
- Water temperature is to be set so as to not go beyond 135°F (57°C)
- Short exposures are best
- Excessive abrasion of plastics in dishwashers can be a voided if the
metal spindles are covered with soft material like a plastic tubing.
- Labware should remain weighted down, accessory racks are used to hold
them in place
Cleaning
with Ultrasonic Cleaners
If Ultrasonic Cleaners are used it should be ensured that the labware
should not rest on the tank's bottom. of the tank. For optimum results using
a cleaning basket is a good method.
How
to Remove Grease and Oils
In most cases grease and oils are removed on washing with a mild detergent.
Another simple way is to use dilute sodium bicarbonate (NaHCO3) and boil the
labware in it. However this does not work with acrylic, polycarbonate,
polystyrene or LDPE.
In case of difficult grease and oils which refuses to go organic solvents
like methylene chloride, alcohols or acetone could also be used. Hoever they
should be used with caution. Prolonged exposure to these type of solvents
may result in swelling of polyolefins. Before the labware is used all
solvents must be rinsed off thoroughly. However only alcohols are to be used
on PC, PS, PSF, or PVC, other types of organic solvents can corrode these
plastics. However a note of caution, organic solvents should never be used
with acrylic.
How
to Remove Organic Matter
To remove organic matter the best way is to soak plastic in a chromic acid
solution. Since chromic acid solution is basically a strong oxidizing agent,
it can have an embrittling effect on plastics. So to lessen the
embrittlement, soaking for 4 hours isd enough.
How
to Remove RNase or DNase from Plastic Containers
RNase is essentially an enzyme which breaks down RNA. DNase can break down
DNA. They both are contaminants which interferes with nucleotide research.
DNase is destroyed effectively by autoclaving for at least 15 minutes at
around 121°C (250°F). For destroying RNase the following among
other methods can prove to be useful. However it is always advisable to
consult an expert before actually performing the task.
- Heating at 180°C (356°F) for a minimum least eight hours
- Rinsing with chloroform
Removing
Hazardous Matter from Plasticware
In case of labware that is contaminated with toxic or infectious materials,
only way out is to perform sterilization by autoclaving. However other
techniques of chemical or heat sterilization which is compatible with the
plastic can also be used. A note of caution liquid waste containing
biohazardous materials should always be decontaminated before disposing of.
You may also like to know about
Sterilising Plastic
Labware
