Abstract: Determination of sodium benzoate in milk powders by the infrared difference spectrophotometry. The experimenresults demostrate regression equation of concentration-A was obtained:A = -0.001873 + 0.4295 C,relation coefficient r=0.9986, the sodium benzoate concentrations in 0～2.5 (mg/g ) with ΔA obeying linear relation. The recovery is 103.6% and thecoefficient of variation is 1.20. The method is precise, simple and satisfactory.

Key words: infrared difference spectrophotometry, sodium benzoate, milk powders