Ethidium bromide
From Wikipedia
Ethidium bromide (EtBr) is an intercalating agent commonly used as a nucleic acid stain in molecular biology laboratories for techniques such as agarose gel electrophoresis. When exposed to ultraviolet light, it will fluoresce a red-orange color, especially when it binds to DNA (20-fold increase). This is likely not due to rigid stabilization of the phenyl moiety, because the phenyl ring has been shown to project outside the intercalated bases. The increased hydrophobicity of the environment is believed to be responsible. Because it binds to DNA, ethidium bromide is a very strong mutagen, and may possibly be a carcinogen or teratogen. Important hazard information follows. As with most fluorescent compounds, it is aromatic. The main portion of the molecule is a tricyclic structure with aniline (amino-benzene) groups on either side of a pyridine (six-atom, nitrogen-containing, aromatic ring). The dibenzopyridine structure is known as a phenanthridine. A nucleic acid is a complex, high-molecular-weight biochemical macromolecule composed of nucleotide chains that convey genetic information. ... Molecular biology is the study of biology at a molecular level. ... Digital printout of an agarose gel electrophoresis of cat-insert plasmid DNA Agarose gel electrophoresis is a method used in molecular biology to separate DNA strands by size, and to determine the size of the separated strands by comparison to strands of known length. ... Note: Ultraviolet is also the name of a 1998 UK television miniseries about vampires. ... Fluorescence induced by exposure to ultraviolet light in vials containing various sized cadmium selenide (CdSe) quantum dots. ... In chemistry, a phenyl-group is a hydrophobic aromatic functional group which is derived from benzene (C6H6). ... In chemistry, a moiety is a specific segment of a molecule. ... In biology, a mutagen (Latin, literally origin of change) is an agent that changes the genetic information (usually DNA) of an organism and thus increases the number of mutations above the natural background level. ... In pathology, a carcinogen is any substance or agent that promotes cancer. ... Teratogenesis is a medical term from the Greek, literally meaning monster making. ... A compound is an area of land that is surrounded by fences, walls, or barbed wire and is used for a particular purpose, especially an area containing buildings and where the entry and exit of people is controlled. ... In chemistry, an aromatic molecule is one in which electrons are free to cycle around circular arrangements of atoms, which are alternately singly and doubly bonded to one another. ... Aniline, phenylamine or aminobenzene (C6H5NH2)is an organic chemical compound which is a primary aromatic amine consisting of a benzene ring and an amino group. ... Pyridine is a clear liquid with a strong and very unpleasant odor that is used as a solvent and reagent in organic chemistry. ...
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Hazards
Ethidium bromide is strongly mutagenic and is irritating to the eyes, skin, mucous membranes and upper respiratory tract. The health effects of ethidium bromide exposure have not been thoroughly investigated. It is suspected to be carcinogenic and teratogenic because of its mutagenicity, although there is no direct evidence of either effect. The toxic effects of ethidium bromide may be experienced if swallowed, inhaled or absorbed through the skin.
Safe Handling
Preparation of stock solutions and any operations capable of generating ethidium bromide dust or aerosols should be conducted in a fume hood to prevent inhalation. Gloves should be worn at all times. Latex gloves offer little protection from ethidium bromide -- nitrile gloves are much more effective. When working with high concentrations or for a prolonged period of time, double gloving can further reduce the risk of exposure, especially if the outer glove is replaced whenever significantly contaminated.
Spills or Personal Exposure
As with any chemical, if spilled on skin or eyes, rinse for 15 minutes using a safety shower or eyewash. If inhaled or swallowed, seek medical attention immediately.
For spills, use a spill pillow or absorbent to soak up aqueous ethidium bromide. Carefully clean up solid ethidium bromide to avoid creating dusts. Place in a sealable container and dispose in a medical waste box.
Waste Disposal
Electrophoresis Gels
Trace amounts of ethidium bromide in gels should not pose a hazard. Higher concentrations, e.g., when the color of the gel is dark pink or red, should not be placed in laboratory trash. EHS recommends the following:
* Less than 0.1% ethidium bromide: place in laboratory trash * More than or equal to 0.1%: place in biohazard box for incineration.
Ethidium Bromide Solutions
Solutions containing ethidium bromide should be deactivated, neutralized and poured down the drain with copious amounts of water. Deactivation may be confirmed using UV light to detect fluorescence. There are three recognized methods for deactivation:
Armour Method
This is the simplest method, but is somewhat controversial. One study found traces of mutagenic reaction mixtures using this method. (Lunn, G. and E. Sansone, Analytical Biochemistry, vol. 162, pp. 453-458, 1987) 1. Combine equal amounts of ethidium bromide solution and household bleach. 2. Stir constantly for four hours or let sit for 2-3 days. 3. Adjust pH to 4-9 with sodium hydroxide. 4. Pour down drain with copious amounts of water.
Lunn and Sansone Method
For each 100 ml of ethidium bromide solution: 1. Add 5% hypophosphorus acid. 2. Add 12 ml of 0.5 M sodium nitrate. 3. Stir briefly and let stand for 20 hours. 4. Adjust pH to 4-9 using sodium hydroxide. 5. Pour down drain with copious amounts of water.
Quillardet and Hoffnung Method
This method uses 0.5 M potassium permanganate and 2.5 M hydrochloric acid. Since chlorine gas may be released in significant concentration, EHS does not recommend using this method.
Charcoal Filtration
Filtering the aqueous ethidium bromide waste solutions, free of other contaminants, through a bed of activated charcoal is a relatively simple and effective method for removal of ethidium bromide. Schleicher and Schuell (603-352-3810 or http://www.s-and-s.com) supply commercial filter funnel kits that use packaged charcoal disks that are graduated for easily tracking the amount of aqueous solution calculated for a fixed quantities of ethidium bromide residue.
1. Filter the ethidium bromide solution through charcoal filter. 2. Pour filtrate down the drain. 3. Place charcoal filter in a sealed bag (e.g., Zip-loc) and place in biohazardous waste box for incineration.
Gloves, Equipment and Debris Gloves, test tubes, paper towels, etc., that are grossly contaminated with ethidium bromide should be placed in medical waste for incineration. Consider deactivating in bleach before disposal if the items are significantly contaminated.
Other Names
Ethidium bromide is also known as:
- 2,7-diamino-N-ethyl-6-phenyl-phenanthridinium bromide
- 2,7-diamino-10-ethyl-6-phenyl phenanthridinium bromide
- 2,7-diamino-10-ethyl-9-phenyl phenanthridinium bromide. FW 394.3, C21H20N3Br.
Note: hazard information was copied verbatim from http://www.princeton.edu/~ehs/wastepaper/99-4.html In chemistry, especially in organic chemistry and biochemistry, an amino group is an ammonia-like functional group. ... Ethyl is a two-carbon substituent in organic chemistry. ... In chemistry, a phenyl-group is a hydrophobic aromatic functional group which is derived from benzene (C6H6). ... General Name, Symbol, Number bromine, Br, 35 Series halogens Group, Period, Block 17 (VIIA), 4, p Density, Hardness 3119 kg/m3 (300 K), NA Appearance Gas: red-brown solid: metallic luster Atomic properties Atomic weight 79. ... In chemistry, especially in organic chemistry and biochemistry, an amino group is an ammonia-like functional group. ... Ethyl is a two-carbon substituent in organic chemistry. ... In chemistry, a phenyl-group is a hydrophobic aromatic functional group which is derived from benzene (C6H6). ... General Name, Symbol, Number bromine, Br, 35 Series halogens Group, Period, Block 17 (VIIA), 4, p Density, Hardness 3119 kg/m3 (300 K), NA Appearance Gas: red-brown solid: metallic luster Atomic properties Atomic weight 79. ... In chemistry, especially in organic chemistry and biochemistry, an amino group is an ammonia-like functional group. ... Ethyl is a two-carbon substituent in organic chemistry. ... In chemistry, a phenyl-group is a hydrophobic aromatic functional group which is derived from benzene (C6H6). ... General Name, Symbol, Number bromine, Br, 35 Series halogens Group, Period, Block 17 (VIIA), 4, p Density, Hardness 3119 kg/m3 (300 K), NA Appearance Gas: red-brown solid: metallic luster Atomic properties Atomic weight 79. ...
