Calcium (Ca²⁺) or Magnesium (Mg²⁺) is an essential metal ion in biological systems.  These divalent ions are also common components in biochemical buffers and pharmaceutical products. The MicroMolar Calcium / Magnesium Assay Kit is for measurement of micromolar concentrations of calcium, and magnesium (10 µM – 120 µM).  The assay may also be used to detect other divalent metal ions.  The assay is based on the complex formation of the divalent metal ion with the assay reagent that results in reduction of the fluorescence intensity (emission 535 nm, excitation 485 nm).  Chelators such EDTA and thiol compounds bind divalent ions and should be avoided in the assay.  The assay is compatible with HEPES buffer, low concentrations of non-ionic detergent (<0.01%), Tris-HCl (<10 mM), and phosphate (< 1 mM). It is not compatible with thiol compounds such as DTT, 2-mercaptoethanol or cysteine. It is interfered by divalent metal ions such as Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, Hg²⁺and Zn²⁺.  For specific assays of transitional metal ions such as Cu²⁺and Zn²⁺, please visit http://www.profoldin.com/concentration.html.

The assay kit can be used for measurements calcium or magnesium concentrations in buffer samples or pharmaceutical products.

The MicroMolar Calcium / Magnesium Assay Kit (catalog number DMA200) includes 200 µl of 100 x C56 dye and 1000 µl of 10 x Reagent E and 50 µl of CaCl₂.  It is for measurement of 200 samples using 96-well plates.  Cuvettes may also be used for measurements.