[Nhcoll-l] [MOGELIJK SPAM ! ******] Teststrips for formalin

[A.J.van_Dam at lumc.nl]

Dear Esther,

When you want to quantify residual traces of formaldehyde in ethanol preserved specimens that were initially fixed with formalin, you can test the sample according to the instructions without dilution. 100mg/L = 0.01% formaldehyde in water.

If you want to quantify the concentration of old, possibly degraded formalin 10% (= formalin 40% diluted ten times = 4 weight% formaldehyde in water) used as final preservative instead of alcohol, you need first to dilute the sample, preferably 200 times.

As a practical example, take a 1 ml formalin sample out of the specimen container and add to 0.2 liter deminerilized water and mix/stir well. Take of this diluted mixture the sample needed for the quantofix test. If you have a colour intensity read-out matching with the 100mg/L mark of the stick, the real concentration of formaldehyde in the specimen jar is a 200 times higher which is in this case 20g/L = 2% formaldehyde in water (formalin 5%). If the original concentration was 4% (formalin 10%), half of it might have been degraded to formic acid and/or paraformaldehyde or partly escaped as a gas out of the container. By using this dilution method you can now roughly quantify formaldehyde concentrations between 0.2% and 4% (formalin 0,5% to 10%).

Cheers,

Dries

Andries J. van Dam | Conservator

Museum of Anatomy | Leiden University Medical Center | Building 3 (V3-32)
P.O.Box 9600 | 2300RC Leiden | The Netherlands
Visiting address: Hippocratespad 21 | Tel: +31 (0)71 52 68356 | E-mail: A.J.van_Dam at lumc.nl<mailto:A.J.van_Dam at lumc.nl>

Scientific associate | Natural History Museum London | http://www.nhm.ac.uk
Director | Alcomon Company | http://www.alcomon.com
________________________________
Van: nhcoll-l-bounces at mailman.yale.edu [nhcoll-l-bounces at mailman.yale.edu] namens Esther Dondorp [esther.dondorp at naturalis.nl]
Verzonden: vrijdag 19 september 2014 9:39
Aan: nhcoll-l at mailman.yale.edu
Onderwerp: [MOGELIJK SPAM ! ******] [Nhcoll-l] Teststrips for formalin

Dear all,

We have a test from Quantofix (Macherey-Nagel) with teststrips that get darker when there is more formaldehyde in the solution.

This test gives you mg/L HCHO, and I would like to know how to translate this to percentages of formalin.

For example, what is the percentage of formalin when the test result is 100 mg/L HCHO formaldehyde.

Is there another way to easily test the formalin percentage of a solution?

Many thanks!

Esther Dondorp

Collection manager Reptiles and Amphibians
Naturalis Biodiversity Center




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