We have a leak in our application system (bottle with spray head) and there are 4 possible ways that Ethanol (80% solution) evaporate through one or more. We hope to identify the leaking spot by passivly colouring it. Any ideas? Thanks a lot!!
The good "colourising" impurity in ethanol that is volative like ethanol but has a very unplesant odour is SCl2. Brown colour you can see any concentrations when your alkohol fly. But SCl2 is aggressive and slowly reacts with ethanol. Orto-nitrophenol, yellow color not agressive, flies with water stream readily but witn alkohol stream not so readily, but flies. Orto-nitro aniline... I' m not sire if it will fly in vacuo. but after distilling off an ethanol from o-nitroaniline solution distillate is noticeble yellow
Maybe a dye isn't the best idea. I can't think of any that would co-evaporate with EtOH. If it were my project (and given a well equipped lab -or access to a reasonable University facility) I'd spike the sample with about 0.1uC of 14C-labelled ethanol ... and then spray it in a contained box, swab the area and then scan the surface of the container with a Geiger counter. Narrow area swabbing and scintillation counting of the swabs would provide definite results. OK this is drastic.
The problem might be able to be turned round. Have you thought of putting a dye on the OUTSIDE of the container to detect the leak?
Hi. I thank all of you for your great and interessting suggestions!
Kirill, I was wondering, since we know that the leak releases only little amount of EtOH (10-100mg over 9 weeks), it will be hard to detect a coloured cloud or something. My question is, is one of your colorants likely to produce a condensation on the glas or on plastic parts of the bottle or will it get off in the atmosphere like the EtOH? Thanks a lot!
Robert, your suggestion are also great, but since we do not have the facilities to work with 14C labelled ethanol, it is unfortunately not possible to follow your idea. Your turned around approach is tempting though. So, we need to find a colorant that changes its colour when having contact with volatile EtOH. Do you have any suggestions what might be suitable? Or Kirill do you?
Thanks again!
Diane
There are a number of kits available to measure low concentrations of ethanol. (Think of the breath tests used by police?) Maybe you could modify the alcohol oxidase method. This produces H2O2 from EtOH - the peroxide then oxidises a dye giving a colour reaction. I believe Abcam market a ' Ethanol Assay Kit' which might be suitable the dye they use gives a yellow/green colour. A suggestion is to swab the reagents on the outside of the container and look for a colour change. It would possibly be more sensitive to look at flourescence - but you might not have the equipment. You might have to do a bit of work to develop a technique but it is the best answer I have.
Helium leak detection is ultimate solution.
Less stringent are ammonia test and SiCl4 /TiCl4 test.
Fill your bottle with 25% NH3 aq. , warm slightly and with glass stick wetted by HCl conc. looking for white smoke. We have experience in such examination of small autoclave closures.
SiCl4/TiCl4 test is same but based of sensitivity to humidity. In places of possible leaks, this compounds build with time white crusts of oxides.
However, looking on minute amount of ethanol lost , I tend to thihk about direct diffusion through plastic walls (check compartability) or spraying head.
I think Andrei provided your best answer. He certainly has the experience.
Thanks a lot Andrei and Robert! We will go for it! Have a nice week!!!
Best Regards.
Diana
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