Science Buddies: "Ask an Expert"

We are working on "How sweet it is, How much glucose is in you drink?", as a science fair project. We we're moving along very well and suddenly we seem to have hit a snag. The test strips really only show a slight difference in the range of pinks. Should we have gotten a definite color change in each of the variables? 4% 2% 1% .50% ect.. For example should the
4% glucose solution have been the darkest color? We have already taken back one box of strips because there was no change at all and they were out of date. The 4% solution is showing small 15 g. Does this seem correct? Can you give some advise? Frustrated!!!

We need help advise from anyone who has used the urinalysis strips for this project. The question is simple did you get a color variation other than a trace for your control variables? Did you get a color variation in the items tested? We have now spent close to $50 on a project that I don't think will work. Please advise if you have used this item or have done this project. My daughter is ready to throw in the towel!!!

It must be frustrating.

Non-results are part of science. Can you tell us the brand and type of test strips you are using.
Investigating why your experiment does not give the expected results is still a good question in my opinion.

You already found an issue with supplies out of date. If after reviewing the procedure and steps you still don't get the expected results, I would continue to question the strips. I did a quick search and product reviews talk about some strips expire "quickly".

Like William, I would be interested in knowing what kind of strips you used. You do have glucose strips for urinalysis, not ketone strips, right? That is one thing to be sure and check.

When testing your control solutions, the project offers these guidelines:

"If you do not have a clear color change for any of the positive control solutions with a concentration greater than 0.0625%, or if the test for any solution is more than one color off from what it is expected to be (for example, if the 1% solution reads less than 0.5% or the 0.25% solution reads greater than 0.5%), repeat the procedure; if it still is problematic, buy new test strips."

From what you said, it sounds like you have only seen trace results for all of your test solutions?

The 4% solution you checked should definitely be registering on the sticks. If you look at the color chart on the strips, the farthest one probably shows something like 2 (for 2%). ("On the bottle there will probably be colors for 0% ("Negative"), 0.1% ("1/10"), 0.25% ("1/4"), 0.5% ("1/2"), 1% ("1"), and 2% ("2") glucose solutions, as shown in Figure 2 below.")

You may not be able to post an image here in the forums, but if you want to take a picture of your bottle of strips, you can email them to me at [email protected].

Amy
Science Buddies

Maybe we have purchased the wrong testing strips. Ketone Testing Strips-Reagent Strip for Urinalysis in a store brand and the ReliOn brand.

It does sound like you may have the wrong strips. Keto strips are used to measure ketones. Glucose strips measure glucose.

It can be confusing because the same companies make both kinds.

For this project, you do need to use glucose strips for urinalysis, not keto (or ketone-measuring) strips.

Diastix say glucose on the box; the ketone version (Ketostix) say ketone on the box. ReliOn may also make both kinds.

Amy
Science Buddies