Thymol blue  (Synonyms: Thymolsulphonephthalein)

Thymol blue is a reversible pH indicator that responds to the pH of the solution through structural changes of protonation and deprotonation. Thymol blue is red (HI^- form) under acidic conditions and blue (I^2- form) under alkaline conditions. Quantitative detection is achieved through the absorption peak shift (435 nm/596 nm) of the UV-visible spectrum. Thymol blue selectively responds to pH changes, changing from red to yellow at pH 1.2-2.8 and from yellow to blue at pH 8.0-9.6. Thymol blue can be fixed in a silica gel matrix through sol-gel technology to form a solid-state sensor for in-situ pH measurement in the marine environment and acid-base monitoring in the biomedical field[1][2].

Thymol blue 酸碱指示 protocol (溶液态)^[1]：
1. 溶液配制
将 Thymol blue 钠盐溶于乙醇 (或水/乙醇混合溶剂)，配成 0.1% (w/v) 储备液。
2. pH 响应测试
取待测溶液，滴加 1-2 滴 Thymol blue 指示剂：
酸性条件（pH<1.7) 溶液呈红色（HI^- 形式）。
中性至弱碱性 (1.7≤pH≤8.9：溶液呈黄色 (中间态。
强碱性 (pH>8.9)：溶液呈蓝色 (I^2-形式)。
3. 定量检测
使用分光光度计测量 435 nm (HI^-) 和 596 nm (I^2-) 吸光度，计算比值 R=A₅₉₆/A₄₃₅，通过电离公式计算 pH 值。

MCE has not independently confirmed the accuracy of these methods. They are for reference only.

466.59

C₂₇H₃₀O₅S

76-61-9

固体

Brown to breen

百里香酚磺酞；百里香酚兰；麝香草酚磺酞；百里香酚磺钛；麝香草酚磺钛；百里酚兰；瑞香酚兰；麝香草酚兰

Room temperature in continental US; may vary elsewhere.

4°C, protect from light

*In solvent : -80°C, 6 months; -20°C, 1 month (protect from light)

• [1]. Huining Zhang, et al. Spectrophotometric pH measurements of surface seawater at in-situ conditions: absorbance and protonation behavior of thymol blue. Marine Chemistry,Volume 52, Issue 1,1996, Pages 17-25.

  [2]. Zaggout F R, et al. Behavior of thymol blue analytical pH-indicator entrapped into sol-gel matrix[J]. Materials Letters, 2006, 60(29-30): 3463-3467.