Method for determining surfactant concentration in aqueous solutions

A method of determining a surfactant concentration below a critical micelle concentration (“CMC”) of the surfactant in an aqueous solution comprising the steps of:

• a) collecting a sample of the aqueous solution having a surfactant concentration below the CMC;
• b) adding an ionic strength adjuster to the sample to induce a suppressed CMC for the surfactant;
• c) adding a dye composition to the sample, the dye composition being generally insoluble in water;
• d) maintaining the sample for a predetermined reaction period to prepare a test solution;
• e) visually comparing the test solution with a plurality of standards corresponding to known micelle concentration levels to approximate the surfactant concentration of the aqueous solution.

A method of determining a surfactant concentration below the critical micelle concentration (“CMC”) of the surfactant in an aqueous solution comprising the steps of:

• a) collecting a sample of the aqueous solution having a surfactant concentration of less than 5% of the CMC of the surfactant in the aqueous solution;
• b) treating the sample with a sufficient quantity of an ionic strength adjuster to the sample to induce a suppressed CMC for the surfactant and adding a dye composition to produce a treated sample, the dye composition being generally insoluble in water;
• d) maintaining the treated sample for a predetermined reaction period to prepare a test solution;
• e) measuring the absorbance of the test solution at a wavelength to obtain an absorbance value;
• and
• f) comparing the absorbance value with a calibration curve to determine the surfactant concentration of the aqueous solution.