From my experience, it's hard to handle that way.

We buy in in 1 lb quantities, and have frequently had to discard powder purchased in the fall, when things would start up the following spring. This happened, in spite of opening the bottles only two times, and in spite of storing them carefully.

However, since adding desiccants to the DPD powder containers, we're seeing evidence that the powder sometimes remains good over the winter. Consequently, we're planning (later, after the kits are caught up) to offer 25g refill vials, with extra desiccant paks added, and with intructions to keep the powder indoors and opened as rarely as possible.

So, if you receive the powder in good condition (white or nearly so), add some bulk desiccant packs to your DPD powder containers, bag it along with additional desiccants, and open it rarely and only indoors . . . you might succeed.

Keep in mind, through, that the Taylor DPD powder in our kits is actually a Taylor's blend of powder, stabilizers and buffers for use in the FAS based testing. Pure DPD powder cannot be substituted, nor can the DPD powder HACH sells for use in colorimetric tests. So, you'll need to purchase from Taylor.

If you do, be sure to purchase during the summer, when they are blending and shipping immediately. I've gotten some old stock in the spring that I had to send back.

Ben