Nonionic surfactants modified Dragendorff reagent

The bismuth active substances (BiAS) method for the determination of nonionic surfactants with barium tetraiodobismuthate (BaBil4, modified Dragendorff reagent) is used in the standardized (DIN-Norm) procedure in Germany, as well as in other countries. Ba as a hard Lewis acid forms cationic coordination complexes with the polyethoxylate chain of the nonionic surfactants, which are precipitated by [Bim in the presence of acetic acid. The orange precipitate is then dissolved with ammonium tartrate solution, and the released bismuth ions are determined by potentiometric titration with pyrrolidinedithiocarbamate solution. Waters et al. optimized the BiAS procedure by introduction of a cation/anion exchange clean-up of the sublation extracts. The BiAS procedure fails to determine ethoxylates with less than five ethoxy units because these compounds are not precipitated by barium tetraiodobismuthate. Thus, this procedure is not suitable for determination of APEO metabolites, i.e., the shorter APEO and AP. ... 

Procedure Qualitative Test for Nonionic Surfactants Using Modified Dragendorff Reagent (45). 

Procedure Spectrophotometric Determination of Nonionic Surfactants After Precipitation with Modified Dragendorff Reagent (87)... 

Procedure Determination of Nonionic Surfactant in Wastewater Using Modified Dragendorff Reagent (48)... 

Wyrwas, B., A. Szymanski, Z. Lukaszewski, Tensammetric determination of nonionic surfactants combined with BiAS separation procedure precipitation of different ethoxylates with modified Dragendorff reagent in the proposed and cla.ssical BiAS procedure.s, Talanta, 1994, 41, 1529-1535. 

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