Guanidinium Salt Lysis Reagents

Videlock Laboratory · lab-specific standard operating procedure

This is a laboratory-written SOP, not a UCLA EH&S template. It is pending review with EH&S (laboratorysafety@ehs.ucla.edu) before being filed in the Chemical Hygiene Plan. The signed copy of record, with the PI approval and training signatures, is in the lab safety manual.

This SOP covers nucleic-acid lysis and binding buffers built on guanidinium salts. Their GHS classification (mostly acute toxicity category 4) does not trigger any UCLA control band, but the reaction of guanidinium thiocyanate with bleach produces cyanide gas — a hazard created entirely by how the waste is handled, and that no banded SOP addresses. Use is subject to pre-approval by the PI.

Materials covered

Hazard description

Guanidinium thiocyanate reacts with sodium hypochlorite (bleach) to release cyanogen chloride and hydrogen cyanide. Contact with strong acid releases hydrogen cyanide and hydrogen sulfide. Both reactions are fast and happen at room temperature in an ordinary waste container or sink.

This is a realistic laboratory accident, not a theoretical one: the usual sequence is decontaminating a bench or a waste container with bleach while guanidinium waste is present, or pouring lysate into a sink that has just been bleached.

The buffers themselves are irritants and acute toxicity category 4. QIAzol is far more hazardous than the others because of its phenol content — phenol is absorbed rapidly through intact skin and causes painless chemical burns.

Personal protective equipment

Lab coat Gloves Eye protection
Traditional white lab coat, buttoned, sleeves down. Nitrile gloves, changed immediately on contact. For QIAzol, double-glove — nitrile gives only brief protection against phenol. ANSI Z87.1-compliant safety glasses; chemical splash goggles when handling QIAzol or pouring any volume over 50 mL.

Engineering controls, equipment and work practices

   
The bleach rule Never bring bleach into contact with guanidinium waste, guanidinium-contaminated glassware, or a sink or bench where guanidinium waste has been poured. If a surface needs both, use 70% ethanol or a quaternary disinfectant instead, or bleach first and rinse thoroughly with water before any guanidinium work begins.
Fume hood Open QIAzol and any phenol-containing lysis reagent only in a fume hood. Non-phenolic guanidinium buffers may be used on the open bench with the PPE above.
Waste segregation Guanidinium waste gets its own clearly labelled container. Do not combine it with halogenated solvent waste, acidic waste, or any bleach-containing stream.
Labelling Label the waste container “Guanidinium thiocyanate — DO NOT ADD BLEACH OR ACID” in addition to the standard UCLA hazardous waste tag. Post the same warning at the sink if guanidinium work is done nearby.

Labeling and storage

Store at room temperature in the original closed container, in a labelled secondary container, segregated from bleach, acids and oxidizers. QIAzol must additionally be stored per the UCLA Phenol SOP.

Housekeeping

Spills. Absorb with pads and clean with water and detergent only — NEVER with a bleach-based cleaner. For a QIAzol or other phenol-containing spill, follow the UCLA Phenol SOP: the spill kit must contain PEG-400 or glycerol, since water is not effective for phenol on skin. Bag all cleanup material as solid hazardous waste. For a spill larger than 100 mL, or any spill of phenol-containing reagent outside a hood, evacuate and call 9-1-1 from a campus phone or (310) 825-1491 from a cell phone.

Decontamination. Wipe contaminated surfaces with detergent and water unless specified otherwise above. Dispose of contaminated towels as solid hazardous waste.

Waste

All guanidinium-containing liquid waste goes into a labelled aqueous hazardous waste container — never down the drain. Phenol-containing waste (QIAzol, the phenol phase from an extraction) goes into a separate labelled container per the UCLA Phenol SOP. Pipette tips, tubes and towels contaminated with these reagents go into solid hazardous waste.

Refer to the UCLA Chemical Hygiene Plan for general waste accumulation requirements.

First aid and emergencies

   
Suspected cyanide gas release Leave the area immediately, close the door behind you, and call 9-1-1 from a campus phone or (310) 825-1491 from a cell phone. Tell responders that guanidinium thiocyanate may have contacted bleach or acid. Do not re-enter.
Skin contact — phenol-containing reagent Remove contaminated clothing. Wipe the skin with PEG-400 or glycerol, then wash with copious water. Seek medical attention even if there is no pain — phenol burns are initially painless because phenol anaesthetises the nerve endings.
Skin contact — non-phenolic buffer Wash with soap and water for 15 minutes.
Eye contact Flush at an eyewash for 15 minutes and seek medical attention.
Inhalation Move to fresh air; seek medical attention if symptoms persist. Notify EH&S at (310) 825-9797.

Emergency: 9-1-1 from a campus phone, or (310) 825-1491 from a cell phone · UCLA EH&S: (310) 825-9797

Training

Everyone who works with these materials reads this SOP and signs the training record held in the lab safety manual.

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