Selective and sensitive chromo- And fluorogenic dual detection of anionic surfactants in water based on a pair of "on-off-on" fluorescent sensors

A pair of relatively sensitive sensors for anionic-surfactant detection due to the formation of 1:1 complex without complicated sample pretreatment were provided. Five related dyes were specifically designed and simply synthesized to detect the anionic surfactant SDS at a relatively low concentration with both absorbance and fluorescence intensity changes. The results show that the addition of SDS to a solution of the dye in neutral water results in fluorescence quenching centered at 526 nm and a regular decrease in absorption spectrum. Both the emission and absorption spectra has no evident change in SDS concentration range of 7.2-2400 nm. It is also found that the 1:1 complex of SDS is formed with an associated constant 1.15×10⁶M^-1. The quenching effect of SDS decreases with increasing ionic strength in neutral water, and 0.01M and 0.15M phosphate buffer solution, the fluorescence yields are 91, 89, and 65%.