engleski

Green Analytical Chemistry Principles in Anionic Surfactant Detection by Potentiometric Sensors

Standard methods for anionic surfactants (ASs) determination are based on formation of the ion-pair compounds between the ASs and cationic dye methylene blue (MB): for real samples it is a volumetric method with visual end-point detection [1(a)], while for low levels of ASs in water it is a spectrophotometry of methylene blue active substance (MBAS) [1(b)]. This methods suffers from several serious drawbacks such as numerous matrix interferences, use of chloroform – toxic and carcinogenic organic solvent, they are time-consuming, tedious etc., but still most commonly used all over the world. Among many other analytical techniques, potentiometric determination of ASs with AS ion-selective electrode as indicator has numerous advantages: they are highly selective, fast and easy to perform, inexpensive etc. [2]. In term of sample preparation for real samples only dissolution is required, while for wastewater it is even simpler: the determination is performed directly in the water sample. Because of all these features it can be considered as a truly green analytical method [3]. In this investigations liquid-membrane potentiometric sensor with hexadecyltrioctadecylammonium-tetraphenylborate ion-pair (HTA-TPB) as ionophore was used as the end-point detector in potentiometric titrations [4]. Titrations were performed on model solutions (Figure 1) and on 6 samples: 3 real samples (products containing ASs) and 3 samples of industrial wastewaters. Results compared with results obtained by the standard methods [1] confirmed a high degree of agreement (Table 1).

anionic surfactants, green chemisry, potentiometric sensors, wastewater

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