Chlorophosphonazo-III

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Item #	Description/Size	Availability	Qty Break	Price	Quantity
C010-10	100 mg	5-10 business days	1	$36.00
C010-12	1 g	5-10 business days	1	$216.00

*Estimated. Exact shipping date will be notified.
For Research Use Only Products

Application: Alkaline earth metals detection, colorimetric

Description
Application
Data

ChemicalName: 2,7-Bis(4-chloro-2-phosphonophenylazo)-1,8-dihydroxy-3,6-naphthalenedisulfonic acid
CAS: 1914-99-4

Appearance: Reddish brown or black purple crystalline powder
Absorbance (0.018 mmol/l): ≥0.530 (around 550 – 570 nm)
MW: 757.37, C₂₂H₁₆Cl₂N₄O₁₄P₂S₂
Storage Condition: ambient temperature, protect from metal
Shipping Condition: ambient temperature

Product Description

Chlorophosphonazo-III is a colorimetric reagent for thorium, uranium, lanthanoids, actinoids, and alkaline earth metals. This reagent is readily soluble in water and is violet at pH 4 or lower, blue in NaOH solution, and brilliant green in acids such as H₂SO₄, HCl and diluted HNO₃ (it decomposes in concentrated HNO₃). Its proton dissociation constants are reported to be -1.1, -1.1, 0.6, 0.8, 1.5, 2.5, 5.47, 7.20, 12.15 and 15.13 (μ=0.1, 20ºC). Chlorophosphonazo-III is used as a selective colorimetric reagent for calcium in a mixed Ca/Mg sample in the pH range of 2-3. It is also a useful indicator for the precipitation titration of SO₄^2- using Ba²⁺ as a standard solution.

Chemical Structure

References
1. L. R. Snyder, et al., Characterization and Routine Determination of Nonbasic Nitrogen Types in Cracked Gas Oils by Linear Elution Adsorption Chromatography. Anal Chem. 1964;36:767-773.
2. J. W. Ferguson, et al., Simultaneous Spectrophotometric Determination of Calcium and Magnesium with Chlorophosphonazo-III. Anal Chem. 1964;36:796-799.
3. D. S. Howell, et al., Ultramicro Spectrophotometric Determination of Calcium in Biologic Fluids. Anal Chem. 1966;38:434-438.
4. T. Yamamoto, Extraction-photometric Determination of Uranium(IV) with Chlorophosphonazo-III. Anal Chim Acta. 1973;65:329-334.
5. M. Zenki, et al., Repetitive Determination of Calcium Ion and Regeneration of a Chromogenic Reagent Using Chlorophosphonazo III and an Ion Exchanger in a Circulatory Flow Injection System. Anal Sci. 2002;18:1137-1140.

Table 1 Metal Detection Conditions Using Chlorophosphonazo-III