Application: Alkaline earth metal detection, colorimetric

Chemical Name: 3,3 EBis[N,N-bis(carboxymethyl)aminomethyl]-o-cresolphthalein
CAS: 2411-89-4

Appearance: White or slightly yellowish pink powder
Absorbance (Ba chelate): ≥0.800 (around 578 nm)
Absorbance (Blank): ≤0.090 (around 575 nm)
MW: 636.60, C32H32N2O12

Storage Condition: ambient temperature, protect from metal
Shipping Condition: ambient temperature


Product Description
PC is a colorimetric reagent and metal indicator for alkaline earth metal ions. This reagent is slightly soluble in water and readily soluble in aqueous ammonia or organic solvents. The aqueous solution is colorless at pH 11, but turns a strong pink in the presence of alkaline earth metals. PC is widely utilized for the determination of serum calcium by an autoanalyzer.

Chemical Structure


Chelate titration: Ca, Ba, Mg, Sr, CN, SO42-
Colorimetry: Ca, Ba, Hg(II), La, Mg, Sr

Ba: pH 11.3, 575 nm, detection range 0-5 ppm Ca: pH 10.5, 575 nm, detection range 0-1 ppm
Hg: pH 10, 585 nm, detection range 0.1-4 ppm La: cetylpyridiniumbromate, 617 nm, detection range 0-2 ppm
Mg: pH 10, 570 nm, detection range 5-30 ppm Sr: pH 11.2, 575 nm, detection range 0-3 ppm

1. G. Anderegg, et al., Metallindikatoren VII. Ein Auf Erdalkaliionen Ansprechendes Phtalein und Seine Analytische Verwendung. Helv Chim Acta. 1954;38:113-120.
2. J. Bosholm, Spektrofotometrische Bestimmung von Calciumspuren Nachihrer Abstrennung aus Konzentrierten Lithiumchlorid-losungen Mittels Kationenaustausch. Anal Chim Acta. 1966;34:71-77.

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Ion Analysis Reagents

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