Determination of ultra trace amount Chromium in water samples with the 1-(2-PyridylAzo)-2-Naphthol, (PAN) by the bromate ion in sulfuric acid with kinetic spectrophotometric method

Document Type : Research Paper


1 Chemistry Department, Dashtestan Branch, Islamic Azad University, Dashtestan, Iran

2 Chemistry Department, Islamic Azad University, Kangan branch, Kangan, Iran

3 Young Researchers and Elite Club, Shiraz Branch, Islamic Azad University, Shiraz, Iran


A new kinetic spectrophotometic method for the determination of trace amount Chromium (III) in Tea
real samples has been described based on it s the catalytic effect on the oxidations of 1 - ( 2 –
PyridylAzo ) - 2 - Naphthol, (PAN), by potassium bromated in sulfuric acid. The reaction is followed
spec- trophotometrically by measuring the decrease in the absorbance at 469 nm. Under the optimum
conditions of0.2 molL-1 sulfuric acid, 1.0 × 10-4 molL-1, 1- ( 2 -PyridylAzo ) - 2 - Naphthol, (PAN),
0.01 molL-1 potassium bromate at 35oC, calibration graph in the rang of 0.001-0.06 ngL-1 Chromium
(III). Concentration was obtained with detection limit of 0.2303 g mL-1 by the fixed-time method of
5.5 min. The relative standard deviation for 0.05AngL-1 Chromium (III) is %90. No serious interference
was identified. The applicability of the method was demonstrated by the determination of the
Chromium (III) in Water, Vegetables and blood samples.