Automated liquid-phase microextraction into alkyl polyglucoside-based supramolecular solvent: Determination of tetracyclines in saliva

Abstract

This work presents for the first time a flow-based approach for the automation of the liquid-phase microextraction process into environmentally benign alkyl polyglucoside-based supramolecular solvent formed in situ under coacervation with fatty acid. The procedure entails spontaneous phase separation without centrifugation within a mixing chamber of a flow system. Electrolytes were employed to increase density of the aqueous sample phase so that the extract separated on the top of the mixing chamber. It allowed faster and better phase separation (4 min required), dispensing the sample phase, and aspirating the exact volume of the supramolecular solvent phase conveniently and reproducibly. Alkyl polyglucosides C₈-C₁₀ and C₈-C₁₄, decyl and coco glucosides were investigated as amphiphiles for automated microextraction. The microextraction of tetracycline antibiotics from saliva samples after deproteinization followed by determination using high-performance liquid chromatography with ultraviolet detection was performed as an example. The supramolecular solvent based on decyl glucoside and 1-hexanoic acid provided good extraction performance (extraction recovery values up to 92 %) along with low viscosity. The limits of detection, calculated from blank tests based on 3σ, were determined to be 10 μg L^-1 for minocycline and oxytetracycline along with 20 μg L^-1 for tetracycline and doxycycline.