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RB058 Methanal Solution

Methanal solution, also known as formalin or formaldehyde solution, is acutely toxic by inhalation and should be handled with caution, including the use of personal protective equipment and fume cupboards. The document provides guidance on preparing methanal solutions, including dilution instructions and necessary hazard warnings. It emphasizes the importance of securely closing containers to prevent gas diffusion and recommends consulting additional guidance for handling fixatives and preserving fluids.

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22 views1 page

RB058 Methanal Solution

Methanal solution, also known as formalin or formaldehyde solution, is acutely toxic by inhalation and should be handled with caution, including the use of personal protective equipment and fume cupboards. The document provides guidance on preparing methanal solutions, including dilution instructions and necessary hazard warnings. It emphasizes the importance of securely closing containers to prevent gas diffusion and recommends consulting additional guidance for handling fixatives and preserving fluids.

Uploaded by

byron.aram7
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Recipe 58

Methanal solution

58 Methanal solution
Methanal is acutely toxic by inhalation. It diffuses from solutions and, at concentrations ≥ 0.1%, the WEL
(STEL) will be approached in localised situations (eg, just above open containers/test tubes/preserved
specimens). Inhalation of the vapour would act at least as a respiratory irritant.
It is advisable to include a warning to this effect on any labels used on prepared solutions.
Also known as formalin or formaldehyde solution.
Methanal itself is a gas at room temperature but is supplied commercially as an aqueous solution (usually
about 35-40 % w/w) with a stabiliser (eg, methanol) added to minimise oxidation and polymerisation. The
stabiliser content varies by supplier, which may affect the hazard classification; check supplier’s information.
The dissolved gas gradually diffuses from solution; the concentration will fall over time. Ensure bottle tops
are securely closed on stored containers.
Fixatives/preserving fluids: Refer to detailed CLEAPSS guidance for any activity involving these.

Read this Recipe in conjunction with the following guidance:


• Hazcard 63
• Labelling chemicals in schools (Guide GL 111).

Formula: HCHO Molar mass: 30.03 g mol-1


Volume (cm3) of concentrated stock solution (~ 35-40 %) to be used
Concentration Volume (cm3) of solution required
Hazard warning label
required 500 1000 2500

0.1 % 0.03 M Ten-fold dilution of a 0.3 M solution with water DANGER

0.3 % 0.1 M Ten-fold dilution of a 1 M solution with water

1% 0.3 M 13 25 63
DANGER
3% 1M 38 75 190

4% 1.3 M 50 100 250

Preparing methanal solutions


1. Wear splash-proof goggles. Protect the face. Wear gloves. Use a fume cupboard.
• The gas diffuses from solutions and pressure will build up in containers. Cautiously open the bottle in
an efficiently-working fume cupboard. Ensure laboratory is well-ventilated.
2. Measure out the indicated volume of stock solution in a suitable measuring cylinder.
3. Add the liquid to about two-thirds of the final volume of water in a beaker or laboratory jug.
4. Stir to mix.
5. If a beaker has been used, pour the solution into an appropriately-sized measuring cylinder or
laboratory jug and add water to the required final volume. Mix well.
6. Pour the solution into a labelled bottle. Include hazard warning and/or control measure information on
the label if appropriate.

RB 058 - 11/24 ©CLEAPSS®


Page 1 of 1 science@cleapss.org.uk; www.cleapss.org.uk

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