Combination of doped amorphous carbon based dispersive solid phase extraction with ionic liquid-based DLLME for the extraction of aromatic amines from leather industries wastewater; Theoretical and experimental insights

In the present investigation, combination of dispersive solid phase extraction with ionic liquid-based dispersive liquid-liquid microextraction was used for the extraction of several aromatic amines from leather industries wastewater. In this approach, initially, N and S doped carbon was used for the adsorption of the analytes from the sample solution and then they were concentrated by the subsequent microextraction step. Determination of the extracted analytes was performed using high performance liquid chromatography-ultraviolet detector. The sorbent contact area with the sample solution was enhanced by performing aspiration/dispersion cycles. In the microextraction procedure, the analytes were enriched into a few microliters of an ionic liquid. Also, interactions between some ionic liquids and the studied aromatic amines were analyzed in the light of performed density-functional theory calculations. The calculated quantum chemical parameters and binding energies for the interactions between ionic liquids of the selected amines showed that the analytes interact powerful with the mentioned ionic liquids and it favorite for the method. The optimized method validation was followed by evaluating several figures of merit and the obtained data showed that limits of detection and quantification, precision (expressed as relative standard deviation), enrichment factor, and extraction recovery were in the ranges of 0.25–0.71 and 0.86–2.4 ng/mL, 3.9–5.2%, 252–312, and 63–78%, respectively. The introduced approach was used in determination of the analytes in the wastewater samples collected from leather manufacturers and p–anisidine, p–chloroaniline, and diethylaniline were determined in them, successfully.