Standard Operating Procedure
Hydrofluoric acid (and solutions
1- General notice
(These are not
authorized official regulations for general use of HF and HF-based
solutions. But, these are valuable rules to protect your safety and
everyone should follow these rules whenever using HF in the LAMP
Before you start, read the Material
Safety Data Sheet for hydrofluoric acid carefully as well as of
solutions containing HF such as Buffered Oxide Etch (BOE) (http://www.enma.umd.edu/LAMP/lamp_msds.htm).
More details about medical treatment for HF exposure available
here (pdf format)
Additional safety information is also listed in the
Lab Safety section
of this web site.
is not like any other acids. It is considered as extremely hazardous
either as a liquid or vapor.
cause severe burns which can take up to 24 hours before being visible or
painful. However it will readily be absorbed into the skin and bind with
calcium and magnesium to form insoluble salts. These insoluble salts
will interfere with cellular metabolism, causing cellular necrosis and
You must know that BOE is not a
dilute HF. The ratio given on the BOE container is buffer to HF, so the
fluorine content is the same as in HF for any ratio
Any LAMP users who want to use HF or
HF-based solution such as BOE must be qualified and authorized by the
lab manager prior to do any work.
During the qualification process, the lab
manager will insure that the Materials Safety Data Sheets for HF-based
chemicals have been carefully read and understood, and that the
procedures detailed in this SOP are thoroughly followed.
The list of the authorized users is published on
this web site. If your name is not on this list, you are not allowed
to use HF or HF-based solutions at any time.
Any accident regarding the use of HF must be
reported without delay to the lab manager.
The handling of HF solutions require special protection equipment in
addition to the regular clean room protection outfit (see Lab Safety
The additional protective equipment include: a full face shield, PVC or neoprene
gloves (regular Nitrile gloves used in LAMP will not provide sufficient
protection), as well as a PVC acid apron to wear on top of the lab coat.
Gloves are located in the acid cabinet, apron and mask are available in
the fitting room.
a reminder, open-toed shoes are not allowed when working in
the lab and bare legs must be covered by wearing a full size bunny suit.
3 - HF handling
- HF solutions, as well as any corrosive or hazardous substances,
can only be used in LAMP during operational hours (9 am to 6 pm,
Monday to Friday) and requires at all time the presence of a second
knowledgeable user (buddy system).
- HF vapors are extremely hazardous. Therefore HF solutions can be
only handled under the flow hood dedicated to work with
- Whenever handling HF, all containers used during the experiment
must be very clearly labeled and a warning sign, visible by any user
working under the flow hood, must be posted at all time to indicate
that the solutions contains HF.
- After completion of the work, the user will insure that all
surfaces in contact with HF have been carefully rinsed with DI water
and blown dry. The user must also insure that the HF bottle is
perfectly dry before being stored in the acid cabinet.
4 - HF waste disposal
- You must know that BOE is not a dilute HF. The ratio given on
the BOE container is buffer to HF, so the fluorine content is the same as
in HF for any ratio. For this reason, the same amount of Calcium Chloride
must be used when neutralizing BOE as when neutralizing HF.
- HF solutions or BOE must be collected
in the dedicated plastic containers, located on the tray next to the flow hood
- Do not completely fill up the waste container with HF solution.
- The waste containers will be discarded by the student in charge of the
waste management according to DES waste
5 - Emergency procedure
- As stipulated earlier HF solutions are considered extremely
hazardous because their effects are not immediate and the fluoride ion
will penetrate the skin causing destruction of the deep tissue layers
and even bone. It has been reported
little as 7 ml of anhydrous HF in contact with the skin untreated can
bind on the calcium in a normal size adult.
- In case of
large exposure, the victim should be removed from the contaminated
area, placed under a safety shower while emergency personal is
In any case, even if the burn appear initially
minor, you must seek immediate medical attention. A copy of the MSDS
that contains a note to the physician should be brought with you.
- All contaminated
clothing should be removed immediately with appropriate gloves and
- In case of contact with
the skin, the affected area must be immediately rinsed with large
amounts of water for at least 15 min. However washing off the skin
will not be sufficient. A calcium gluconate gel contained in a white
tube is available in the LAMP facility (in the First Aid box located
to the right of the lab entrance door). The gel should be massaged
over the affected area. When applying the gel, the washing with water
can be reduced from 15 to 5 min. The gel should be reapplied at
- In case of contact with
the eye, irrigate the eye for at least 30 minutes, keeping the eyelids
apart and away from eyeballs during irrigation. Place ice pack on eyes
until reaching emergency room.
Supply and storage
In order to
limit the number of HF containers in the lab, all
solutions containing HF are supplied by the lab. If for specific
research purposes, you need your dedicated source of hydrofluoric acid,
you must request the authorization from the lab manager first.
Supplied HF solutions are typically diluted to 37%. If you need to
adjust this concentration, you will supply your own container for
a polyethylene bottle
with a positive closure
(never store in a glass container since HF attacks glass and other
silicon containing compounds)
All HF-containing solutions will be stored in the acid cabinet located
under the flow hood. It is not allowed to leave the lab with a HF
solution left on the bench top under the flow hood.
If you notice that the supply of HF or BOE is running out, contact the
student in charge of chemicals
inventory (do not wait the last minute though since it can take up to 4
weeks to renew the supply)
Prepared by L.
Henn-Lecordier; last update: August 2002 by L. Henn-Lecordier