Quinhydrone powder - to Calibrate ORP probe

[Boret]

In order to calibrate the ORP probe in the Aquacontroller III I need to make my own 2 solutions with pH4.0 solution and pH7.0 solutions, mixed each, to the point of saturation, with Quinhydrone powder.

 

Where can I get that powder locally? Do any of you have some I could buy? Do any of the LFS carry it?

 

Thanks!

[ctenophore]

Interesting. Curt @ Neptune assured me that no calibration was necessary. I'm curious to know if your probe needs adjusting as it seems logical to me that calibration would be necessary. I was planning to check mine with Pinpoint's 400 mV solution.

[Boret]

I spoke to Curt and he told me to get that powder to be able to calibrate with the ACIII.

You can check how OFF your probe is with the PinPoint 400 redox solution, but Curt also mentioned that he doesn;t trust the solution that much...

I tested my probe and it was reading 394 after about 45 mins in the solution, so I need no calibration, but it would be nice to get the powder.

This is the only one I found so far:

 

LINK

 

$40 plus shipping for 25g.

[davjbeas]

I have the pinpoint calibration solution packets in PH7 and PH10 but those are used for PH probe calibration. I don't understand why you would use PH calibrating solution for an ORP probe.

 

David

[ctenophore]

I spoke to Curt and he told me to get that powder to be able to calibrate with the ACIII.

You can check how OFF your probe is with the PinPoint 400 redox solution, but Curt also mentioned that he doesn;t trust the solution that much...

I tested my probe and it was reading 394 after about 45 mins in the solution, so I need no calibration, but it would be nice to get the powder.

This is the only one I found so far:

 

LINK

 

$40 plus shipping for 25g.

 

I wonder why he told you to calibrate and me not to worry about it? Either way, the powder costs almost as much as a new probe.

[Boret]

The way the ACIII calibrates the ORP is by placing the probe in two solutions with a determined mV value. The controller calls them Quinn-7 and Quinn-4.

Same basic mechanics as calibrating the pH probe.

However, they don't sell these solutions but you can make them.

 

Redox Standard Quinn-4 - 263mV @ 25oC

 

1. Take a 20ml sample of pH 4 Buffer Solution.

2. Add a small quantity (approx 0.05-0.1g) of Quinhydrone Powder.

3. Shake vigerously to mix.

(Very little quinhydrone will dissolve, so the solution will end up grey/black).

4. The Redox Standard is now ready for use.

5. Discard after use.

 

Redox Standard Quinn-7 86mV @ 25oC

 

1. Take a 20ml sample of pH 7 Buffer solution.

2. Add a small quantity (approx 0.05-0.1g) of Quinhydrone Powder.

3. Shake vigerously to mix.

(Very little quinhydrone will dissolve, so the solution will end up grey/black).

4. The Redox Standard is now ready for use.

5. Discard after use.

[Boret]

He didn't tell me to calibrate, I called and asked what the heck was the Quinn-4 and Quinn-7 coming up in the ACIII screen. It was my decision to calibrate, just in case. I had the Redox 400 and was about to use it when the weird message appeared on the screen, so I called Curt and asked. As a matter of fact, I didn't need to calibrate because once I placed the probe in the 400 solution after 45 mins I was getting a 394 reading.... close enough.

He explained the need to use the Quinhydron powder with pH7 and pH4 solutions to create the Quinn-7 and Quinn-4.

Edited December 24, 2009 by Boret

[Origami]

You may want to see if you can just get an ORP test kit, Boret. Here's one over at Aquarium Specialty: http://www.aquariumspecialty.com/catalog/p...roducts_id=5168

 

It's unclear what exactly the kit comes with (except for 10 packets of stuff). If you can get directions for the kit, you can probably find out.

[Boret]

If that works that would be a great find. Thanks Tom. Cheaper than the quinhydrone powder.

I am a bit affraid of this though:

 

Contents: 5 packets of +92mV, 5 packets of +265mV

 

Quinn-7 is supposed to be +86mv and Quinn-4 263mV

 

The 265mV solution will work but the 92mV is 7% different...

[Origami]

If that works that would be a great find. Thanks Tom. Cheaper than the quinhydrone powder.

I am a bit affraid of this though:

 

Contents: 5 packets of +92mV, 5 packets of +265mV

 

Quinn-7 is supposed to be +86mv and Quinn-4 263mV

 

The 265mV solution will work but the 92mV is 7% different...

 

I'd place a call to the manufacturer to get specifics on what's in the packets and the package, Boret. My suspicion is that it's the quinhydrone you're looking for, just in much smaller quantities than 25 grams. Since your recipe calls for so little quinhydrone, they make a little money on the markup and you save a little by not having to buy enough to last you 25 years. It's possible that the difference in the calibration values may have as much to do with the pH reference formulation as the quinhydrone.