# Tools like Litmus Paper

Litmus papers are used to test acidity and alkalinity of a fluid. Are there other paper-based tools to test for other stuff like dissolved oxygen, presence of toxicity, electric potential etc?

• Hi, Welcome to Chemistry SE. This is good question, it reminded me of paper based battery indicator that worked just like mercury-type thermometer so when the battery potential is full the paper showed full range and if the battery is low then partial range. I can also imagine the plastic based coating on the mugs that turns colorless revealing a picture when hot fluid is poured, there are inexpensive methods to test for various properties. – metron Sep 24 '20 at 19:16
• Pregnancy test kits. Lead paint test kits. – Jon Custer Sep 24 '20 at 19:24
• Yes, available at your local hardware store. Moisten and wipe a painted object, turns color if lead is picked up from it. – Jon Custer Sep 24 '20 at 19:39
• @JhonnyS, I've enlarged the comment a bit and made it an answer. – DrMoishe Pippik Sep 27 '20 at 1:09
• There are paper thermometers (which actually employ a type of liquid crystals) that change colour and show temperature – Shoubhik R Maiti Sep 27 '20 at 21:04

It's easy to find a slew of test papers and strips online. For example, a quick search of Amazon for "test papers" turned up chlorine test strips for pools and sanitation, glucose test strips for diabetes, phenylthiourea genetic-linked taste tests, UV-C dose test cards, lead acetate paper test for $$\ce{H2S}$$, WBC and nitrite test strips for UTI... You could write a paper on all the test papers available.
BTW, you can make a test paper for polarity testing, and for detection of peroxides, by dipping filter paper into a suspension of starch and potassium iodide, $$\ce{KI}$$, rather than buy it. Dampen and use it as you would a potato to determine the polarity of an electric cell.