Introduction of high nitrogen doped graphene as a new cationic carrier in electromembrane extraction.

This paper proposes for the first time, the use of high nitrogen doped graphene (HND-G) as a new cationic carrier for the enhancement of electromembrane extraction (EME) performance. Sensitivity of EME was improved by the modification of supported liquid membrane composition through the addition of HND-G into 1-octanol for the extraction of naproxen and sodium diclofenac as model acidic drugs. The comparison between HND-G-modified EME and conventional EME showed that HND-G could increase the overall partition coefficient of acidic drugs in the membrane due to the fact that HND-G acts as an ion pair reagent and there is an electrostatic interaction between positively charged HND-G and acidic drugs with negative charge. During the extraction, model acidic drugs migrated from a 10 mL aqueous sample solution (pH 9.6) through a thin layer of 1-octanol containing 0.6% w/v of HND-G that was impregnated in the pores of a hollow fiber, into a 30 µL basic aqueous acceptor solution (pH 12.3) present in the lumen of the hollow fiber. Equilibrium extraction conditions were obtained after 16 min of operation with the whole assembly agitated at 1000 rpm. Under the optimized conditions, the enrichment factors were between 238 and 322 and also the LODs ranged from 0.1 to 0.7 ng/mL in different samples. Finally, the applicability of this method was evaluated by the extraction and determination of drugs of interest in real urine samples.

Vortex-assisted ionic liquid microextraction coupled to flame atomic absorption spectrometry for determination of trace levels of cadmium in real samples.

A simple and rapid vortex assisted ionic liquid based liquid-liquid microextraction technique (VALLME) was proposed for preconcentration of trace levels of cadmium. According to this method, the extraction solvent was dispersed into the aqueous samples by the assistance of vortex agitator. Cadmium preconcentration was mediated by chelation with the 8-hydroxyquinoline (oxine) reagent and an IL, 1-octyl-3-methylimidazolium hexafluorophosphate ([Omim][PF6]) was chosen as the extraction solvent to extract the hydrophobic complex. Several variables such as sample pH, concentration of oxine, volume of [Omim][PF6] and extraction time were investigated in details and optimum conditions were selected. Under the optimum conditions, the limit of detection (LOD) was 2.9 µg L(-1) for Cd (ІІ) and relative standard deviation (RSD%) for five replicate determinations of 125 µg L(-1) was 4.1%. The method was successfully applied to the determination of cadmium in tap water, apple and rice samples.