Use 30ml borosilicate glass vials with teflon PTFE lined caps (source: Cynmar Corporation, Item #115-27974, 12pack @ $11.00.) The diameter of the vials is big enough to accommodate the probes, unlike the BOD bottles, and they form a very good watertight seal.

If you want to actually be able to screw the DO probe on to the vial, you need to order the chromatography vials that Wards supplies in its AP lab #4 kit for “Plant Pigments and Photosynthesis”. These are almost the same size as the 30ml glass vials from Cynmar, but the threads on the vial will match the Vernier calibration bottle cap that comes with the DO probe.

All you have to do is just slide the probe through the cap and screw it onto the chromatography vial to take your reading. This is also very nice if you want to do a 24 hour run, because you can keep the probe in the vial and take readings over 24 hours. Just use a little parafilm to assure no leakage from where the probe goes through the cap.

You won’t find the number for extra chromatography vials on the Wards web page or in their catalog, but the item number is #2680530 at $0.75 each. Just be sure that Wards knows you just want the vials and not the kit.