Procedure Purpose
To ensure that Liquid Nitrogen (LN2) for experimental use is readily available to researchers at St George’s, University of London (from now on referred to as St George’s) whilst adhering to strict health and safety standards.
Policy Definitions
The Institutes
Infection and Immunity Research Institute (IIRI)
Molecular and Clinical Science Research Institute (MCSRI)
Institute for Biomedical and Medical Education (IMBE)
Population Health Research Institute (PHRI)
Cryostorage
Storage of samples in liquid nitrogen at -196°C
Dewar
A suitable flask in which LN2 can be safely contained
Cryosectioning
The cutting of thin sections from a block of frozen tissue
Contents
1.1 Scope of Document
This procedure applies to everyone involved in laboratory-based research and teaching at St George’s, including research groups in IIRI, MCSRI, IMBE and PHRI. It is also applicable to Research Operations staff.
1.2 Describe the Task
At St George’s, LN2 is mainly used for cryostorage. Cryostorage takes place within a specialised facility on the basement floor of Jenner wing. In the laboratories of Jenner Wing, however, LN2 is mainly used to snap-freeze samples. Requests for LN2 for snap-freezing and cryosectioning are made to Research Operations staff who will deliver to laboratories.
1.3 Health and Safety Considerations
NB. Always follow the advice given in the LN2 guidelines provided by the SHE Office. Further information can be found in the local-rules template which is available on the SHE Office webpages. A copy of the local rules should also be present within the laboratory.
• LN2 may cause asphyxiation and must be handled in well-ventilated areas.
• LN2, at a temperature of -196°C, can cause severe cold burns and permanent eye damage even by brief exposure.
• Appropriate PPE, including goggles and cryogenic gloves, must be worn when handling LN2.
• Use pincers to withdraw objects immersed in LN2.
• Use only approved containers able to withstand very cold temperatures, such as Dewars (carbon steel, plastic and rubber become brittle at these temperatures).
• Only use containers with loose lids. Never seal LN2 in a container; pressure will build up and the container could potentially explode, forcefully discharging LN2 with potentially devastating consequences.
• Never pour liquid nitrogen down the sink as this could lead to serious damage to pipework.
• Unused LN2 should be left to evaporate at room temperature in a fume hood with the extractor fan running. A notice should be placed on the fume hood, stating that liquid nitrogen is present.
• Never store liquid nitrogen in a sealed room such as a cold room, a lift or a room without adequate ventilation. A litre of liquid nitrogen can expand between 650 and 750 times and rapidly cause the depletion of oxygen in a room.
1.4 Steps to take to Request LN2
1. The day before use, an email should be sent to both Technical Assistants, Gavin Linkson and Mick O’Reilly. This communication will ensure that at least one of them will be available to assist when required.
2. The email must contain your name, the laboratory that the LN2 should be delivered to and the date and time that you require the LN2.
3. In addition, you should arrange where and when you will leave the empty LN2 container for the Technical Assistants to pick up and fill.
4. LN2 will be delivered to the laboratory as arranged or may be collected at the point of distribution.
5. A response will be given at least an hour before the LN2 is required, or, if it is required early in the morning, the response will be given the day before. If the email response time passes, contact Head of Laboratory Services.
6. If after delivery the LN2 needs to be used elsewhere, follow the LN2 guidelines provided by the SHE office. Remember, LN2 must never be accompanied whilst being transported in a lift.
1.5 Contact for Further Advice
Head of Laboratory Services - Dr Priya Madhou
Technical Assistant – Gavin Linkson
Technical Assistant – Michael Aidan O'Reilly
Research Operations Help Desk – email to be confirmed.
SHE Office – health@sgul.ac.uk