# Minor Q about ColoGuard: what's in the preservative bottle? **URL:** \ **Category:** Factual Questions\ **Created:** [November 21, 2022, 3:04pm UTC](https://boards.straightdope.com/t/minor-q-about-cologuard-whats-in-the-preservative-bottle/975320 "2022-11-21T15:04:58Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![gkster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gkster/32/14107_2.png) [@gkster](https://boards.straightdope.com/u/gkster)\ **Post date:** [November 21, 2022, 3:04pm UTC](https://boards.straightdope.com/t/minor-q-about-cologuard-whats-in-the-preservative-bottle/975320/1 "2022-11-21T15:04:58Z")
The collection went smoothly thanks to the tips in the other threads on the board linked below, but I spilled less than half an ounce (a couple of spoonfuls) of the 10 oz preservative bottle contents on my bathroom tile floor, and got a bit on my fingers. It washed off easily enough, but I’m just wondering what it is? The bottle just says “Preservative 290 ml less than 10% EDTA in Tris buffered solution” together with lot numbers and an expiration date The website says: The bottle of liquid contains a preservative **(less than 10% EDTA** in Tris buffered solution). What does this mean? > [@Question about Cologuard](https://boards.straightdope.com/t/question-about-cologuard/925339/23): > > Reviving this old thread to note that my GP is sending me a Cologuard kit at my request. I’m trying to catch up on routine medical stuff that I’ve put off during the pandemic, and it has been ten years since my first colonoscopy. Time to try Cologuard! I just watched the video on how to collect the specimens, and I’m not looking forward to digging around in my own poop. Also, how do you poop a certain amount and no more into that bucket? I’ve no way of portioning it out as I do it. But it … [Consumption to ensure a properly small Cologuard stool specimen - Factual Questions - Straight Dope Message Board](https://boards.straightdope.com/t/consumption-to-ensure-a-properly-small-cologuard-stool-specimen/960474) ---
**Author:** ![gnoitall](https://avatars.discourse-cdn.com/v4/letter/g/bb73d2/32.png) [@gnoitall](https://boards.straightdope.com/u/gnoitall)\ **Post date:** [November 21, 2022, 3:49pm UTC](https://boards.straightdope.com/t/minor-q-about-cologuard-whats-in-the-preservative-bottle/975320/2 "2022-11-21T15:49:26Z")
> [@gkster](#): > > **EDTA** > **[Ethylenediaminetetraacetic acid](https://en.wikipedia.org/wiki/Ethylenediaminetetraacetic_acid)** > > Ethylenediaminetetraacetic acid (EDTA), also called edetic acid after its own abbreviation, is an aminopolycarboxylic acid with the formula \[CH2N(CH2CO2H)2\]2. This white, water-insoluble solid is widely used to bind to iron (Fe2+/Fe3+) and calcium ions (Ca2+), forming water-soluble complexes even at neutral pH. It is thus used to dissolve Fe- and Ca-containing scale as well as to deliver iron ions under conditions where its oxides are insoluble. EDTA is available as several salts, notably disod... > [@](#): > > …EDTA can combine with free metal ions (such as Zinc, Iron, Copper, Magnesium, Manganese) which are often present in food & beverage and as a result keep the color, flavor and odour of food by preventing these ions reacting with food. > **[What is Calcium Disodium EDTA (E385) in Food: Uses, Safety, Side Effects](https://foodadditives.net/preservatives/calcium-disodium-edta/)** > > Learn more food additive - Calcium Disodium EDTA (E385), from production, uses, safety, side effects, vegan, dairy free, comparison with disodium EDTA.  EDTA is pretty near ubiquitous for its low toxicity and general safety and its ability to bind metal ions out of a material that needs to be preserved from metal ion oxydation reactions. ---
**Author:** ![gkster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gkster/32/14107_2.png) [@gkster](https://boards.straightdope.com/u/gkster)\ **Post date:** [November 21, 2022, 8:10pm UTC](https://boards.straightdope.com/t/minor-q-about-cologuard-whats-in-the-preservative-bottle/975320/3 "2022-11-21T20:10:50Z")
Thank you @gnoitall ! And LOL, duh, I didn’t know that EDTA was the name of the bottle contents; it looked like a code for something I didn’t know about. Actually, I’d never heard of EDTA before. Good to know that it’s safe and has low toxicity. ---
**Author:** ![crowmanyclouds](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crowmanyclouds/32/19884_2.png) [@crowmanyclouds](https://boards.straightdope.com/u/crowmanyclouds)\ **Post date:** [November 22, 2022, 7:18am UTC](https://boards.straightdope.com/t/minor-q-about-cologuard-whats-in-the-preservative-bottle/975320/4 "2022-11-22T07:18:14Z")
Someone missed the OJ trial! ---
**Author:** ![Ynnad](https://avatars.discourse-cdn.com/v4/letter/y/4491bb/32.png) [@Ynnad](https://boards.straightdope.com/u/Ynnad)\ **Post date:** [November 22, 2022, 10:56pm UTC](https://boards.straightdope.com/t/minor-q-about-cologuard-whats-in-the-preservative-bottle/975320/5 "2022-11-22T22:56:37Z")
And Tris is short for 2-amino-2-(hydroxymethyl)propane-1,3-diol which is a buffer that should keep the pH in the neighborhood of about 8. It also might function as a chelating agent but probably (I’m just guessing) not as good as EDTA.