University of the Sciences
Environmental Health and Radiation Safety (EHRS) Department
Disposal Procedures for Electrophoresis Buffer Solutions and Gels
Electrophoresis gels are commonly used in molecular biology research laboratories and
teaching laboratories for the identification of DNA and proteins. Gels are typically agarose or
polyacrylamide based. The gel electrophoresis process utilizes either an organic (often
mutagenic) fluorescence dye or, less commonly, an inorganic dye such as silver.
Mutagenic dyes, such as ethidium bromide (EtBr), are commonly used as non-radioactive
organic markers for identifying and visualizing nucleic acid bonds in electrophoreses and in
other methods of gel-based nucleic acid separation. Although ethidium bromide and other
mutagenic dyes are not regulated as hazardous waste by the Environmental Protection
Agency (EPA), they are still potent mutagens that are moderately toxic after an acute
exposure. Therefore, these dyes should not be discarded in the trash or down the sanitary
sewer system (drain disposal), with the exception of exempt concentrations, discussed below.
Do Not Use hypochlorite (bleach) to decontaminate or treat ethidium bromide as it can
produce mutagenic by-products and leave behind up to 20% of the original ethidium bromide.
Always wear proper eye protection, gloves and laboratory coat when using ultra-violet
(UV) light to visualize EtBr to avoid exposing unprotected skin and eyes.
Mutagenic and Non-Mutagenic Dye Solutions
It is important to remember before ordering and/or using any dye solution that the
hazards are understood and you read the Safety Data Sheet (SDS) to see if the dye is
mutagenic, non-mutagenic, or considered an Environmental Protection Agency (EPA)
regulated material.
However, identical disposal procedures must be followed whether you are working with a
mutagenic or a non-mutagenic dye.
The following are examples of dyes that have been determined to have mutagenic
properties:
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Ethidium Bromide
Propidium Iodine
Acridine Orange
SYBR®Green I
SYBR®Green II
SYBR®Gold
GelStar
The following are examples of dyes that have been determined to be non-mutagenic in
Ames testing by independent licensed testing laboratories:
University of the Sciences
Environmental Health and Radiation Safety (EHRS) Department
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SYBR® Safe
GelRed
GelGreen
EvaGreen
Disposal Procedures
Mutagenic and Non-Mutagenic Dye Solutions

Spent running buffer, de-staining, and other aqueous solutions that contain
mutagenic dyes must be collected and disposed of properly, or collected and run
through an approved filter device.

Small quantities of aqueous solutions containing mutagenic or non-mutagenic dye
concentrations <10 μg/ml (10 ppm) may be released to the sanitary sewer system
(drain disposal) if flushed with copious amounts of water. (As long as there are no
other hazardous chemicals/wastes in the container.)

Aqueous solutions containing ≥10 μg/ml must be collected, properly tagged,
labeled, and sealed while stored in the laboratory.
 The aqueous solutions may be disposed of through the University’s
hazardous chemical waste vendor or,
 treated in the laboratory using an appropriate charcoal filter and, released
through the sanitary sewer system (drain disposal) when the filtrate solution’s
concentration has fallen below the permissible limits of <10 μg/ml (10 ppm),
and when flushed with copious amounts of water.
Non-aqueous Solutions

Non-aqueous solutions may not be treated and released through the sanitary sewer
system and must be stored and disposed of as hazardous chemical waste.
Mutagenic and Non-Mutagenic Dye Contaminated Charcoal Filter

Saturated/Spent charcoal filters used for the treatment of mutagenic and nonmutagenic buffer solutions must be collected in a large wide-mouth plastic sealable
container, tagged, labeled and disposed of through the University’s hazardous
chemical waste vendor. The container must remain closed while stored in the
laboratory, unless filters are being added.
Gels Containing Mutagenic and Non-Mutagenic Dyes

Gels containing a concentration of mutagenic dyes <10 μg/ml (10 ppm) may be
placed in a regular trash bag, tied securely, and then placed in the regular laboratory
trash for disposal.
University of the Sciences
Environmental Health and Radiation Safety (EHRS) Department

Gels containing mutagenic dyes in concentrations ≥10 μg/ml (10 ppm) must be
placed in a large wide-mouth plastic sealable container. The container must always
remain closed unless adding gels. The container must be properly tagged and
labeled while stored in the laboratory, and then disposed of through the University’s
hazardous chemical waste vendor.
Glassware/Equipment Containing Mutagenic and Non-Mutagenic Dyes

Glassware and equipment containing mutagenic and non-mutagenic dyes must be
emptied of the liquid solution and the liquid disposed of according to the procedures
listed under Mutagenic and Non-Mutagenic Dye Solutions.

Contaminated glassware and equipment can then be triple-rinsed and the rinsate
can be released to the sewer system as long as the mutagenic and non-mutagenic
dye concentrations are < 10μg/ml (10 ppm), and flushed with copious amounts of
water.

Concentrations of rinsate ≥10 μg/ml (10 ppm) must be collected and disposed of
according to the procedures listed under Mutagenic and Non-Mutagenic Dye
Solutions.
Environmental Protection Agency (EPA) Regulated Dyes

Gel electrophoresis involving silver and other inorganic dyes or hazardous
chemicals regulated by the Environmental Protection Agency (EPA) must never be
filtered, neutralized or treated in the laboratory for drain disposal.

Therefore, stock solutions, rinsate (spent buffered solutions), gels and contaminated
personal protective equipment (PPE) must be collected, properly tagged, labeled
and sealed in the laboratory, and then disposed of through the University’s
hazardous chemical waste vendor.