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.
Um procedimento simples e rápido de microextração líquido-líquido com líquido iônico e agitação vortex (VALLME) foi usado na determinação de quantidades traço de cádmio por espectrometria de absorção atômica com chama (FAAS). O líquido iônico (IL), hexafluorato de 1-hexil-3-metilimidazólio ([Hmim][PF 6 ]), foi usado como solvente extractor. Os íons Cd 2+ foram complexados com pirrolidina ditiocarbamato de amônia (APDC), e então confinados em pequenas gotas de IL pela intervenção do sistema de agitação vortex. Alguns fatores que influenciam na extração tais como pH, concentração de ligante, quantidade de líquido iônico, tempo de extração e efeito da força iônica foram completamente investigados e otimizados. Sob condições ideais, o limite de detecção foi de 1,1 ng mL -1 . O desvio padrão relativo (RSD) foi 4,3% para 20 ng mL -1 de cádmio (n = 10), e o gráfico de calibração usando o método de preconcentração foi linear de 5 a 150 µg L -1 , com um coeficiente de correlação de 0,998. O método proposto foi aplicado com sucesso na determinação de cádmio em amostras de água e folhas de espinafre.A simple and rapid vortex-assisted ionic liquid based liquid-liquid microextraction (VALLME) procedure was used for the determination of trace amounts of cadmium by flame atomic absorption spectrometry (FAAS). Ionic liquid (IL), 1-hexyl-3-methylimidazolium hexafluorophosphate ([Hmim][PF 6 ]), was used as an extractant solvent. Cd 2+ was complexed with ammonium pyrrolidinedithiocarbamate (APDC) and then entered into the fine IL droplets by the assistance of vortex agitator system. Some effective factors that influence the extraction efficiency such as pH, ligand concentration, amount of ionic liquid, extraction time and ionic strength effect were completely investigated and optimized. Under the optimum conditions, the limit of detection (LOD) was 1.1 ng mL -1 . The relative standard deviation (RSD) was 4.3% for 20 ng mL -1 of cadmium (n = 10), and the calibration graph using the preconcentration method was linear from 5 to 150 µg L -1 , with a correlation coefficient of 0.998. The proposed method was successfully applied for determination of cadmium in water samples and spinach leaves.
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.
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