A colorimetric method for the determination of parts/million of nonionic surfactants

Abstract

A method for the determination of nonionics ill low eoncn (0-20 ppm) has been developed. This method is based on the formation of a blue complex between ammonium cobaltothiocyanate reagent and a polyethoxylated compound. This complex is extracted into benzene ~rom a saturated salt solution and measured with a spectrophotometer at 320 m~. The absorbance reading is compared to a standard.The method requires only a single extraction and no prelbninary cohen step is necessary. It is sensitive to polyethoxylated compounds containing three or more moles of ethylene oxide. We have used this method to detect as little as 0.01 mg of nonionic in 100 ml of sample (0.1 ppm). Reaction conditions, sensitivity differences between compounds, interferences and suitability for use in biodegradation studies have been investigated. The accuracy and repeatability of this method is ±3% relative at 20 ppm eoncn.

The in-situ decontamination of sand and gravel aquifers by chemically enhanced solubilization of multiple-component DNAPLS with surfactant solutions. Topical report

“…The flasks were shaken for 24 hours to ensure that equilibrium had been reached. The solutions were then analyzed using either UV analysis or the cobalt thiocyanate dye method for nonionics (Greff et al, 1965). The difference between the initial and final concentrations of surfactant were used to calculate the retardation factor.…”

Etude de l'adsorption de surfactants ioniques et non ioniques sur de la matière végétale carbonisée

“…Les risultats ainsi acquis ont ete confirmes par la mkthode analytique consistant a former avec I'orthophCnanthroline cuivrique un complexe extractible dans la mCthylisobutylcCtone et a le doser par spectrophotometrie d'absorption atomique (19). La concentration residuelle en surfactant non ionique est determinee par spectrophotomCtrie ultra-violette apres complexation par le cobaltothyocyanate d'ammonium et extraction dans le benzene (20). fig.…”

Conformational Study for Ionic Aggregates of Poly(oxyethylene) Dodecyl Ethers with Ferric-Thiocyanate Anion through the Intermediary of Potassium Ion

“…Spectrometric methods are widely used for this purpose, based on the solvent extraction of ionic aggregates between NSs and metal-thiocyanate complex anions, as seen in the Japanese official method. 1 Cobalt(II) tetrathiocyanate, [2][3][4][5][6][7] zinc(II) tetrathiocyanate, 8 and ferric thiocyanate [9][10][11][12][13][14][15] have been used as chromophores. In addition to these inorganic complex anions, organic anions, such as picrate, [16][17][18][19] tetrabromophenolphthalein ethyl ester, 20,21 and erythrosine B 22 have also been proposed similarly.…”

“…1 In addition to this, it is a well-known fact that the colorimetric sensitivity of POENSs depends on the chain length of the ethylene-oxide (EO) moiety, as described in several articles. 3,7,9,10,19 Why can heptaoxyethylene dodecyl ether provide the highest sensitivity 7,9,10,19 compared to other homologous NSs having longer or shorter EO chains? Although such spectrometric methods have been accepted in many analytical laboratories, no one has given any convincing explanation to solve the above questions.…”