DPD powder shelf life

[geoshecks]

Idea:

The DPD powder can be sensitive to moisture/ humidity during storage.
If yours is not in a desiccant jar, go to a local miracle-ear and purchase a hearing aid drying jar which includes a desiccant pillow which may be refreshed in a microwave when saturated. You can place the powder jar in the dryer or place the desiccant pillow in your test kit. This may be especially useful for off-season storage. Cost should be around $10.

 

[duraleigh]

When we receive fresh DPD Powder, it is almost whitish. Within 7 days of breaking the seal, we can see it start to darken......no other explanantion than it is accepting relative humidity.

The DPD powder will continue to darken over time in the 10g jar in your kit but my experience has been that it has virtually no effect on the validity of the test.

I have used powder that was four years old (I know, you're not supposed to do that), dark, and clumpy and still got good test results.

 

[geoshecks]

That's good to know. Mine was changing and I looked it up and several sources said it was the most susceptible of the reagent chems. So i thought of the desiccant jar. But It sounds like I don't need to worry.

So "never mind" :lol:

 

[jagfan]

I have my extra bottle in the fridge - will that be a problem?

 

[PaulR]

I have my extra bottle in the fridge - will that be a problem?

Let it warm up before you open it so you don't get any condensation inside.
--paulr

 

[frustratedpoolmom]

Wish I would have asked before I thru my old jar away. Only a year old, but it was dark grey so I thought it was bad.

 

[duraleigh]

I have my extra bottle in the fridge - will that be a problem?

It's not the best place. Minimizing the changes in temp and relative humidity is probably the best trhing you can do for longevity of all the chemisty. That means storing it in an air conditioned/heated environment and then performing the tests in that same environment.

Temp extremes either way are not beneficial. Putting it in the fridge and then taking it out to test is an uneccessary change in the temp and could certainly cause the DPD powder to accept more RH and then precipitate that back out when it gets cooled back down.

 

[Guest]

I have a vacuum sealer (Foodsaver) and I sealed my extra DPD powder in the jar in a bag. I just opened a bag I sealed 2 years ago and the powder in the jar is still light, the same color as when I sealed it. I kept the sealed bag in my guest bathroom where I keep all my testing supplies. I have another jar of DPD powder that I sealed at the same time that I guess I will be opening in another 2 years.

 

[Guest]

Can't you just switch to the Taylor liquid reagent that Leslie's carries in their stores?

Sue

 

[JasonLion]

Can't you just switch to the Taylor liquid reagent that Leslie's carries in their stores?

No, the FAS-DPD chlorine test requires the R-0870 powder.

The OTO and DPD chlorine tests both work with liquid reagents, but neither one measures high FC levels reliably.