Science, Tech, Math › Science Transition Interval Definition Share Flipboard Email Print boonchai wedmakawand / Getty Images Science Chemistry Chemical Laws Basics Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated October 02, 2019 Definition: The transition interval is the concentration range of a chemical species that can be detected using an indicator. Usually this refers to an acid-base (pH) indicator color change, but the same principle applies to fluorescence or any other visual indicator. Examples: In a titration, the transition interval represents the concentration of a chemical required in order to see the indicator. Below this point, the intensity of the indicator may be too pale or dilute to detect. Similarly, if an upper limit is given in the transition interval, you won't be able to see a color change or other evidence of the indicator, either.