Abstract:

In the presence of peregal, calcium reacts with arsenazo Ⅰ to form a stable purple complex in NH3-NH4Cl buffer solution (pH 9.5), and then with the measuring and reference wavelengths of 570 nm and 480 nm respectively, a new dual-wavelength dual-peak spectrophotometric method for the determination of calcium content was developed in this study. The results showed that the dual-wavelength spectrophotometer is more sensitive than the single-wavelength spectrophotometer, ε0 = 6.16×104 L/mol·cm, and the calcium content accords with Bill’s law in the range of 0 to1.3 μg/ml. The method was applied in the etermination of calcium in milk powder and glucose samples. The obtained results are satisfying.

Key words: dual-wavelength spectrophotometry, rsenazo Ⅰ, calcium