Application: Anionic detergent detection with solvent extraction, colorimetric

ChemicalName: Bis[2-(5-chloro-2-pyridylazo)-5-diethylaminophenolato]cobalt(III) chloride
CAS: 81342-98-5

Appearance: Dark purple crystals
Molar absorptivity: ≥84,000 at 585 nm
MW: 701.92, C30H32Cl3CoN8O2

Storage Condition: ambient temperature
Shipping Condition: ambient temperature


Product Description
Since Co(III)-5-Cl-PADAP is not influenced by chloride or nitrate ions, it is suitable for the colorimetric determination of anionic detergents in seawater. Anionic surfactant can be determined at the ppb level.

Chemical Structure

1. Add 1 ml of HCl (5 M), 1 ml of Co(III)-5-Cl-PADAP solution (0.1% w/v), and 5 ml of toluene to 50 ml of sample solution.
2. Shake the mixture for 5 minutes.
3. Discard the aqueous phase and wash the toluene solution with 25 ml of Co(III)-5-Cl-PADAP (0.002% w/v, pH 1 HCl).
4. Measure the absorbance of the toluene phase at 560 nm.

1. S. Taguchi, et al., Silaned Glass Beads for the Preconcentration and Spectrophotometric Determination of Cobalt with 2-(2-Pyridylazo)-5-diethylaminophenol. Talanta. 1980;27:819-821.
2. S. Taguchi, et al., Bis[2-(2-Pyridylazo)-5-Diethylaminophenolato]Cobalt(III) Chloride as a New Extraction and Spectrophotometric Reagent for Trace Anions. Talanta. 1980;27:289-291.
3. S. Taguchi, et al., An Application of Bis[2-(5-Chloro-2-Pyridylazo)-5-Diethylaminophenolato]Cobalt(III) Chloride to the Extraction and Spectrophotometric Determination of Sulphonated and Sulphate Surfactants. Talanta. 1981;28:616-618.
4. K. Seno, et al., Extraction-spectrophotometric Determination of Higher Carboxylic Acids with Bis[2-(5-Chloro-2-Pyridylazo)-5-Diethylaminophenol] Cobalt(III) Chloride. Chem Lett. 1982;11:645-646.
5. M. Taga, et al., Flotation-spectrophotometric Determination of Phosphate with Bis[2-(5-Chloro-2-Pyridylazo)-5-Diethylaminophenolato]Cobalt(III) Chloride. Anal Sci. 1988;4:181-184.
6. M. Taga, et al., Capillary Isotachophoretic Determination of Phosphate After Enrichment on Membrane Filter as Ion Pair Molybdophosphate with Bis[2-(5-Chloro-2-Pyridylazo)-5-Diethylaminophenolato]Cobalt(III). Anal Sci. 1989;5:219-220.
7. M. Taga, et al., The Spectrophotometric Determination of Phosphate Following the Collection of Ion Pair of Molybdophosphate with Bis-[2-(5-chloro-2-pyridylazo)-5-diethylaminophenolato]cobalt(III) on an Organic Solvent-soluble Membrane Filter. Bull Chem Soc Jpn. 1989;62:1482-1485.

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