Thymolphthalein:
1. Physical state: white crystalline powder
2. Application: an alkaline solution of thymolphthalein in alcohol makes a very good
disappearing ink. The solution starts out blue, but when it absorbs carbon dioxide
from the air, carbonic acid is formed, neutralizing the alkaline solution and causing the blue color to vanish. The color returns when the ink spot is treated with an alkaline solution
Specifications:
Melting point: 251.0~255.0°C
Transition interval: pH 9.3 for colorless, pH 10.5 for blue
Solubility in alcohol: pass
Solubility in NaOH: pass
Residue after ignition: ≤0.1%
Packing:
10g/plastic bottle
Congo red
1. Physical and chemical properties
Appearance: brownish-red powder
Odor: odorless
Solubility: soluble in water
2. Application: used in medicine and as a dye, indicator, and biological stain
3. pH 0 to blue, pH 5.0 to red
Packing: in 25g plastic bottles
Eosin Y, water soluble
1. Physical state: yellow, odorless dry powder
2. Specifications:
Assay: ≥80%
Flexibility test: pass
Water solubility: pass
Alcohol solubility: pass
Loss on weight: 9
NaBr: 2.0
Packing: in 25g plastic bottles
Phenol red
1. Bright to dark red, water-soluble crystalline
2. Application: used as an acid-base indicator and in medicine to test kidney function
and renal blood flow. A solution of phenol red is used as a pH indicator:
its color exhibits a gradual transition from yellow to red over the pH range 6.6
to 8.0. Above pH 8.1, phenol red turns a bright pink (fuschia) color
Packing: in 10g plastic bottles
