Ultraviolet spectrophotometry for rapid detection of melamine in dairy products

[Detection principle]

According to the structural characteristics of melamine , alizarin red is reacted with melamine , and the absorbance of the reactant is measured by ultraviolet spectrophotometry, so as to quickly detect the residue of melamine in dairy products

[Materials and Instruments]

Melamine (analytical grade); acetonitrile (analytical grade); alizarin red (analytical grade); milk powder to be tested; pure water for experiment

[experimental method]

(1) Preparation of test solution Alizarin red solution preparation: accurately weigh a certain quality of Alizarin Red and dissolve it in pure water (pH 7.

Preparation of melamine solution: Weigh .

(2) Pretreatment of the tested sample Weigh 25ug of melamine standard and mix it with 1g of milk powder, dissolve it in 25mL of hot water, add 75mL of acetonitrile after cooling , and place it at room temperature for 30 minutes

(3) Selection of the best detection wavelength Take a 5mL sample (with a melamine content of 25ug/mL) and mix with 2mL of 0.

(4) The selection of the best developer concentration Take 5 mL of sample and mix 2 mL of Alizarin Red solution with different concentrations (0.

(5) The choice of the greatest color development time Take 5 mL of sample and mix 2 mL of the best concentration of Alizarin Red solution, and react at room temperature for 0, 10, 20, 30, 40, 50, and 60 minutes

(6) Selection of the best color development temperature Take 5 mL of sample and mix 2 mL of the best concentration of Alizarin Red solution, and react for 210 min at 25, 35, 45, 55, 65, respectively

(7) Draw the standard curve.

[Result analysis]

The test results are counted, and the melamine content in different milk powders is analyzed

Related link: Rapid detection of melamine in dairy products (kit method)