Introducing a new class of chiral selectors is an interesting work and this issue is still one of the hot topics in separation science and chirality. In this study, for the first time, sulfated maltodextrin (MD) was synthesized as a new anionic chiral selector and then it was successfully applied for the enantioseparation of five basic drugs (amlodipine, hydroxyzine, fluoxetine, tolterodine, and tramadol) as model chiral compounds using CE. This chiral selector has two recognition sites: a helical structure and a sulfated group which contribute to three corresponding driving forces; inclusion complexation, electrostatic interaction, and hydrogen binding. Under the optimized condition (buffer solution: 50 mM phosphate (pH 3.0) and 2% w/v sulfated MD; applied voltage: 18 kV; temperature: 20°C), baseline enantioseparation was observed for all mentioned chiral drugs. When instead of sulfated MD neutral MD was used under the same condition, no enantioseparation was observed which means the resolution power of sulfated MD is higher than neutral MD due to the electrostatic interaction between sulfated groups and protonated chiral drugs. Also, the countercurrent mobility of negatively charged MD (sulfated MD) allows more interactions between the chiral selector and chiral drugs and this in turn results in a successful resolution for the enantiomers. Furthermore, a higher concentration of neutral MD (approximately five times) is necessary to achieve the equivalent resolution compared with the negatively charged MD.

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In this research, we have developed an electrochemical buprenorphine (BN) sensor based on reduced graphene oxide (r‐GO) as an electrode modifier on the screen printed carbon electrode (SPCE) surface. BN oxidation pathway was proposed using voltammetric studies and with the aid of Density Functional Theory (DFT). The effects of various parameters including pH, modifier amount, accumulation time, and accumulation potential on the oxidation peak current of BN were optimized. Under the optimized conditions, the linear response range and the limit of detection were obtained as 0.50–100 µM and 0.16 µM (S/N=3) using differential pulse voltammetry (DPV), respectively. The selectivity of the modified electrode in the presence of potential interferences was also studied, and finally the electrode was successfully employed for the determination of BN in spiked urine samples.

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Schematic illustration of the surfactant assisted electromembrane-extraction (SEME) technique.