Development of a Fiber Optic Evanescent Wave Sensor for Anionic Surfactants Using Ethyl Violet

A rapid and simple method for the determination of anionic surfactants based on an evanescent wave fiber optic was developed using ethyl violet. The sensor was prepared by removing the middle of the multimode fiber cladding. The optical signal from ethyl violet decreased with an increase in the sodium dodecyl sulfate concentration. The calibration curve was linear from 4 to 15 milligrams per liter with a limit of detection of 3.3 milligrams per liter. This simple fiber optic sensor requires a low volume of sample and does not employ extraction with organic solvents compared with conventional methods.