[tripton]

Hi everibody.
I have a trouble with a pH electrode. There is a glass electrode (model Hanna 1131). The electrode doesn´t calibrate any buffer (I tried 4,7 and 10). Is an old electrode and perhaps it must be regenerated. I haven´t so much filling solution and then, I want to clean the electrode before to waste it.
I would like to ask if someone knows some cleaning procedure in order to regenerate the electrode.

Thank you in advance,

Tripton

[Borek]

http://www.ph-meter.info/pH-electrode-cleaning

But most likely you better dump the electrode and buy a new one - could be faster and cheaper.

[profmsg]

i agree with borek. you should buy new electrode which only cost about 50$.
if you really want to clean follow this link

http://www.ph-meter.info/pH-electrode-cleaning

however after cleaning, the value obtained is not reliable for very critical tests. especially in your case where the electrode is ancient

[enahs]

If none of those cleaning tips work for you, as a last resort dip the electrode in 20 wt% ammonium bifluoride, NH₄HF₂. Do this in a plastic beaker, as the ammonium bifluoride will dissolve a little of the glass, exposing fresh surface on the glass electrode. Then wash the electrode with water very well.

Ammonium Bilfouride must NOT contact your skin, as it will result in HF burns.



I disagree that it is a waste of time and pointless in trying to clean it and get it working; if you have all the reagents at hand with excess to spare. If you have to order something to clean it and get it back working, then it is not worth it.

[Borek]

My bad, I posted only one link out of two, the second one being:

http://www.ph-meter.info/pH-electrode-rejuvenating

It doesn't mention bifluoride, but essentially that's the idea behind hydrofluoric acid treatment; to etch some of the glass from the surface.

Enahs, do you have any reference, or have you used bifluoride by yourself?

[enahs]

Enahs, do you have any reference, or have you used bifluoride by yourself?

I have used it before, I obtained the procedure from an Analytical Chemistry book years ago. I added the HF warning .

However, a quick search turns up this site, which looks quite good.
Really long url at electrodesdirect.com
They then recommend a quick soak in HCl as well afterwards, which I have not soaked but I have rinsed with the HCl. They then recommend something I have never done to complete this procedure, soaking in a pH buffer for 24 hours at a pH of less then 7. I believe this is just to protect them selves as to make sure you completely remove all traces of the acids.


Again, like I said, they also say to do it as a last resort.


I would consider that page an excellent source of information, seeing is how their business is electrodes!

[tripton]

Thanks for the answers. I will try step by step with the suggestions.
If doesn´t work, probably I must buy a new one.

About the prices, now I´m working in Argentina and here is necessary to import such components, then the prices are a higer. Anyway if profmsg could give me some reference (model, manufacturer or something) about the $50 electrode I will try to look for it (or some local supplier) for the next time we must buy an electrode (or this time if I can´t fix the old one).

Tripton

[profmsg]

try this site..... if the required type is not in there then let me know.....i have some more sites
thanks


http://www.sargentwelch.com/product.asp_Q_pn_E_WLS30076-52B_EA_A_Combination+Electrodes_E_

[Mitch]

Have you tried calibrating on the millivolts, can often be more reliable anyways.

[profmsg]

Hanna 1131  starts from 75$

http://www.sci-bay.com/catalog.asp

[tripton]

Thanks profmsg, I will try in this pages.
Thanks also to Mitch, I didn´t tried yet. Anyway this instrument must be used by lot of people and very often, then perhaps is more practical to have the direct pH reading. Anyway, I will try to see if works. Thank you for the idea.