Which base bath do you prefer to clean your glassware? iPrOH/KOH, EtOH/NaOH? Is there data showing that one is more efficient than another?

03 March 2015 29 2K Report

I usually use a iPrOH/KOH bath for most glassware, NH4OH whenever there are trace metals, and occasionally aqua regia for any really tough stuff that just won't come off. But I've heard anecdotally that NaOH/EtOH is more efficient. Is there any data to support this? Has anyone tried both and found a preference? Just out of curiosity.....

Phillip Leigh Van der Peet

Piranha is my favourite for stubborn organic residues but it needs to be made and used fresh. I think the difference between the base baths you mentioned is negligible and largely dependant on what you're trying to remove.

https://www.youtube.com/watch?v=mk72x1NYQXU

James Demers

There's probably much more dissolved hydroxide (and alkoxide) when using ethanol, so I would not be surprised if it were more efficient. If your contaminants are very hydrophobic, however, you might find that isopropanol is still superior. As Phillip notes, it depends on what you're trying to remove.

(In the bad old days, we all had chromic acid jars by the sink - we liked that it didn't etch the glass, but I shudder to think of how much chromium we sent down the drains!)

Victor H Ponce

Under certain circumstances the EtOH/NaOH is able to attack glassware, I'd rather prefer a EtOH/KOH solution, as usual, the fresher the stronger.

Mina Namvari

Well, we use iPrOH/KOH in the lab and it did a good job! In case you couldn't remove a chemical from glassware, nitric acid can be used.

Zarko Boskovic

Currently this one (recipe at the end of pdf):

http://bnorthrop.faculty.wesleyan.edu/files/2009/09/CleaningGlassware.pdf

Works well.

Ashis Ranjan Bandyopadhyay

There will be a little/negligible difference between KOH-EtOH and NaOH-EtOH . I would rather use NaOH-EtOH.

Echoing the views of James, I would like to lament for draining so much of chromium in the drainage system in those bad old days. We cannot afford to doing the same now.

Dal N. L.

I usually soaked my glasswares in 2% Decon 90 overnight. It contain 0.5-2% KOH. And sometimes I filled my beaker with decon and sonicate them for about 30 minutes.

Abdulganiyu Amao

I usually washed my glasswares with boiling 2M NaOH and rinsed with distilled water but in the absence of the above chemical I would prefer to use 10% KOH.

Themba Lubazana

I usually use a 1NaOH/IPA mixture and it has far worked well for me, especially if I leave my glassware soaked in overnight in a fume cupboard.

Julio Cesar Bastos Fernandes

Dear Mr Linstadt, I think that besides alkalinity of the medium be important to remove fat, the surface tension is another relevant factor. Ethanol has a surface tension equal to 22.1 mN m-1, while the surface tension of isopropanol is 23 mN m-1 , both measures at 20 ºC (http://www.surface-tension.de/). Hence, mixtures of bases with ethanol has major wettability. This is just a hipothesis that can explain the better efficient of NaOH/EtOH in relation to KOH/ISPrOH. Kind regards.