Low-toxic air-agitated liquid-liquid microextraction using a solidifiable organic solvent followed by gas chromatography for analysis of amitriptyline and imipramine in human plasma and wastewater samples

• An air-agitated liquid-liquid microextraction method was applied using a solidifiable organic solvent for drug extraction.
• Two tricyclic anti-depressant (TCA) drugs were quantified successfully in the plasma samples.
• The applied method has the advantages of simplicity, rapidity, and high efficiency.
• The extraction efficiencies of the proposed method and the conventional AALLME were compared.

A rapid and low-toxic microextraction method, namely air-agitated liquid-liquid microextraction (AALLME), was applied for the extraction of amitriptyline and imipramine from the human plasma and wastewater samples by solidification of the floating organic solvent droplets (SFO). Using very simple tools, the analytes contained in 10.0 mL of an aqueous sample solution were simply extracted into the solidifiable organic solvent 1-dodecanol. For this purpose, in the absence of an organic disperser solvent, a mixture of the aqueous sample solution and the extraction solvent was repeatedly aspirated and dispensed using a syringe, and by enlarging the surface area between the donor and acceptor phases, a fast and efficient extraction was achieved. The response surface methodology (RSM) was used to optimize the experimental parameters involved. 14.0 μL of the organic solvent used, a pH value of 12.0, 7.52% (w/v) salt addition, and 13 air-agitation cycles for the extraction number were found to be the optimal extraction conditions. Under the optimized experimental conditions, AALLME-SFO-GC-FID provided a good linearity in the range of 15–2000 ng mL− 1, low limits of detection (5.0–7.0 ng mL− 1), good extraction repeatabilities (relative standard deviations below 8.4%, n = 5), and enrichment factors (EFs) of 682–731. In order to verify the performance of the method, the extraction efficiencies of the method based on the solidifiable organic solvent and the conventional AALLME method based on halogenated solvents were compared.