A microextraction method for the determination of triclosan and methyltriclosan in marine environmental samples was developed. The disperser was first serves as a preliminary extractant for analytes, then as a frozen solvent to remove impurities at -20 °C, and finally as a disperser agent in the microextraction procedure. With the extractants solidified and float on the surface of the aqueous phase at low temperature, a separation was achieved to avoided use of specialized laboratory instruments. The method was optimized using Plackett-Burman design and central composite design as follows: 146 μL octanoic acid as extractant, 793 μL acetoneas disperser, 3.0 min centrifugation and 1.1 min vortex time. The limits of detection were 0.022-0.060 μg L^-1 or μg kg^-1 and recoveries were 83.3-103.5% for TCS and MTCS in seawater, sediments and seafood. The method has excellent prospects for sample pre-treatment and trace-level analysis of triclosan and methyltriclosan in marine environmental samples.

This study developed a new effervescence-assisted switchable fatty acid-based microextraction combined with solidification of a floating organic-droplet (EA-SFAM-SFO) for simple and rapid determination of fluoroquinolones and tetracyclines in seawater, sediment, and seafood. Five medium-chain fatty acids (pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, and nonanoic acid) were tested as an extraction solvent, given their ability to change between hydrophobic and hydrophilic forms by pH adjustment. As nonanoic acid had the highest extraction recovery (>92%) for the six antibiotics and the ability to transform from liquid to a solidified floating state at low temperature, it was selected as the optimum extraction solvent. The prominent advantages of the newly developed method are: (1) reaction between the procedures salt and fatty acid changed extraction solvent from the hydrophobic to hydrophilic state; (2) bubbling with CO₂ greatly increased the contact area between fatty acid and analytes resulting in improved extraction recovery; and (3) solidification of the fatty acid at a low temperature provided good separation and avoided the use of specialized equipment. Single-factor screening and optimization of the main factors were conducted using Plackett-Burman design and central composite design, respectively. The main parameters were optimized as follows: 258 μL fatty acid, 406 μL H₂SO₄ (98%), 3.9 min vortex time, and 354 μL Na₂CO₃ (2 mol L^-1). Under optimized conditions, limits of detection were 0.007-0.113 μg L^-1 or μg kg^-1 and extraction recoveries were 82.2%-116.7% for six fluoroquinolone and tetracycline antibiotics in seawater, sediments, and seafood. The newly developed method combines the advantages of effervescence-assisted dispersion, hydrophobic/hydrophilic switchable solvent, and liquid/solid transition induced by low temperature. Overall, the new method is simple, quick, and environment-friendly with low detection limits and high recoveries. Thus, the newly developed method has excellent prospects for sample pretreatment and analysis of antibiotics in marine environmental and food samples. Graphical Abstract ᅟ.