engleski

The Application of Microfluidics for Anionic Surfactant Determination

Anionic surfactants (AS) are represented with 58% of the total global production of surfactants. Standard methods for determination of AS in wastewater and commercial products are MBAS (Methylene Blue Active Substances), and two-phase titration. Because of the shortcomings that both standard methods have, there is a need for replacing them. Potentiometric measurements with the ion-selective electrode (ISE) solved most of the problems of standard methods. Microfluidics methods offer new possibilities in determining AS exploiting the ability to control molecules in space and time. Flow injection analysis (FIA) and Sequential injection analysis (SIA) using the screen-printed microsensor with incorporated new ionic associate (dimethyldioctadecylammonium-tetraphenylborate, DDA-TPB) as a detector, were used for determination of the AS. The measured electromotive force (EMF) is a function of the AS concentration in the sample. Sodium dodecyl sulfate (NaDDS) and sodium dodecyl benzene sulfonate (NaDBS) were used for calibration. The real samples are commercial products and industrial wastewater with different contents of AS. The sensor showed a sub-Nernstian slope for both anionic surfactants. Measurements were performed with adjusted ionic strength and pH. The results showed good agreement with those obtained using the standard methods.

anionic surfactant; dimethyldioctadecylammonium-tetraphenylborate; FIA/SIA; microfludic; potentiometric

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