Abstract: Color reaction of Se-Sb-Mo heteropoly acid with butyl rhodamine B was investigated.Heteropoly blue was produced by treatment of Se-Sb-Mo heteropoly acid with ascorbic acid,which was precipitated after addition of butylrhodamine B.The resulting precipitation was isolated into toluene by suspension and was measured by spectrophotometry after dissolved in ethanol.The results indicate that,at the maximum absorption wavelength 556 n m,the molar absorptivity is 1.341×105 L·mol-1·cm-1 and obeys Lamber-Beer Law at the selenium concentration 0~0.8  μｇ/mL.This method is suitable for determination of trace selenium in vegetables and fruits.

Key words: selenium, butyl rhodamine B, spectrophotometry