DPD Powder ?

[MCR500]

Well, due to an unforseen error (spilled most of it!!! ), I'm running really low on the DPD powder.

I know I can order refills from TF, but there is a $15 min., and even ordering the two pack (at $13.50+shipping) doesn't meet the required order minimum. I REALLY don't need any other testing titrants to make up the order difference!!

My question is, at my local Leslie's, they don't have DPD powder( assistant- "Huh, what do you need that for. Never heard of it" )

They DO have DPD tablets in a 50 count pack. Will, I assume, 1 tablet work for each TF DPD test??

Will the tablets work at all? Are the tablets the same chemical as the supplied TF DPD powder?

Advice/suggestions pls. Thanks in advance.

Mike

 

[JasonLion]

You want Taylor R-0870, not the tablets. You can get it from many different places on the Internet, including at the Amazon store (though not from Amazon) and Leslie's web site.

 

[Guest]

The tablets are not the same as the DPD power. They are the solid equivalent of the liquids used in the colormetric DPD test and are not suitable for the titration test.

 

[dschlic1]

What is the difference between the two types?

 

[Guest]

DPD tablets come in DPD1 and DPD3 for the FC and TC tests They are the same as the three liquid reagents used for the DPD test. DPD1 is the same as R0001 and R0002 and give a colorimetric readout of FC (using a comparato). DPD3 is the same as R0001, R0002, R0003 and is also used with a comparator. Taylor does not offer the tablets but LaMotte, Hach, and Paintest do.
The chemistry of the FAS-DPD test is different and the reagents are not interchangeable. All three companies that offer this test (Taylor, LaMotte, Hach/Aquatrend) use DPD powder along with the titrant liquid and the DPD powder is not the same as the liquid DPD reagents or the tablets. The ONLY reagent that is the same is the R0003 which is sodium iodide (or potassium iodide) and is used to convert ANY oxidizer (be it FC, CC, Bromine, MPS, Ozone, or peroxide) into an iodine compound that can be tested by DPD or titrated by FAS-DPD. This is why there is interference from MPS and ozone with this test and why they show up as CC. The test is not selective for CC but for ANY oxidizer in the water that can oxidize sodium or potassium iodide.

NONE of these different 'DPD' reagents are pure DPD but are mixtures of different chemicals that include some DPD. The mix differs, depending on how the test is being done!