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Chlorophenol red is an indicator dye that changes color from yellow to violet in the pH range 4.8 to 6.7. The lambda max is at 572 nm.
C 2147 (OTTO) Chlorophenol red, GR Cas 4430-20-0 - used to detect chlorine dioxide in drinking water. Transition Interval: From pH 4.8 (yellow) to pH 6.7 (violet). Also used in transport studies of goldfish renal tubules.