CALCIUM OCC Cromatest Liquid Chemistry Reagents
PRINCIPLE
The method1 is based on the specific binding of cresolphtalein complexone (OCC), a metallochromic indicator2, and calcium at alkaline pH with the resulting shift in the absorbtion wavelength of the complex. The intensity of the cromophore formed is proportional to the concentration of total calcium in the sample.
OCC + Calcium OCC-calcium complex
REAGENT COMPOSITION
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OCC indicator. o-Cresolphtalein complexone 0.16 mmol/L, HCl 60 mmol/L, 8-quinolinol 7 mmol/L.
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OCC buffer. AMP 0.35 mol/L, pH 10.7.
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Calcium standard. Calcium 10 mg/dL (2.5 mmol/L). Organic matrix based primary standard.
STORAGE AND STABILITY
Store at 15-30ºC.
The reagents are stable until the expiry date stated on the label.
REAGENT PREPARATION
Working reagent. Mix 1 volume of R1 + 1 volume of R2. Stable 8 days at 2-8ºC. Recap reagents immediatelly after use.
Discard the mixture if the blank presents an absorbance above 0.600 at 570 nm against distilled water or if it fails to recover the declared values of control sera (see Notes).
