A paper-based analytical device for the determination of hydrogen sulfide in fuel oils based on headspace liquid-phase microextraction and cyclic voltammetry.

An easily performed miniaturized, cheap, selective and sensitive procedure for the determination of H2S in fuel oil samples based on a headspace liquid-phase microextraction followed by a cyclic voltammetry detection using a paper-based analytical device (PAD) was developed. A modified wax dipping method was applied to fabricate the PAD. The PAD included hydrophobic zones of sample and supporting electrolyte connecting by hydrophilic channel. The zones of sample and supporting electrolyte were connected with nickel working, platinum auxiliary and Ag/AgCl reference electrodes. The analytical procedure included separation of H2S from fuel oil sample based on the headspace liquid-phase microextraction in alkaline solution. Then, sulfide ions solution obtained and supporting electrolyte were dropped on the zones followed by analyte detection at + 0.45 V. Under the optimized conditions, H2S concentration in the range from 2 to 20 mg kg-1 had a good linear relation with the peak current. The limit of detection (3σ) was 0.6 mg kg-1. The procedure was successfully applied to the analysis of fuel oil samples.

Deep eutectic solvents as a new kind of dispersive solvent for dispersive liquid-liquid microextraction.

In this paper, deep eutectic solvents (DESs) were investigated as a new kind of dispersive solvent for effective dispersive liquid-liquid microextraction (DLLME) for the first time. It was established that the DESs can increase the extraction efficiency compared to conventional polar, water-miscible organic dispersive solvents.