Flow-Injection Specrophotomemic Determination of Calcium Using PAN as a Color Agent

A spectrophotometric method for determination of Ca in aqueous solution using 1-(2-pyridylazo)-2-naphthol (PAN) as color reagent based on the formation of Ca-PAN Complex at pH 12 and measuring absorbance at 550nm, with molar absorptivity of 1.70×10
⁴
L.mol
^-1
cm
^-1
has been modified to a flow injection-spectrophotometric (FI) method. The modified FI method is rapid, accurate, precise, and with low operation cost. The linear range of 1-8ppm was obtained with average recovery of 103.46 and precision of 1.5-3.4%. The proposed FI method using PAN as a color reagent was applied satisfactorily for the assay of Ca in natural water, milk, yogurt and human serum.