Random dendrite growth and the severe shuttle effect of lithium polysulfides are major obstacles to exploiting dependable high-capacity Li–S batteries.
A novel method based on the enhancement effect of room temperature ionic liquids for hollow-fiber liquid-phase microextraction trace amounts of mercury combined with UV–Vis spectrophotometry for the determination of Hg was developed. The addition of room temperature ionic liquids led to 6.0 times improvement in the determination of mercury. Under optimized conditions, an enrichment factor of 120 could be obtained, and the detection limit for Hg was 0.2 ng mL−1. The relative standard deviations for five replicate determinations of 20 ng mL−1 Hg(II) was 5.4%. The proposed method was successfully applied to certified reference materials and environmental water samples with satisfactory results for the determination of Hg.
A novel method was developed for the chemical vapor generation (CVG) of lead, cadmium and bismuth based on the enhancement effect of room temperature ionic liquids followed by thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS) determination. Room temperature ionic liquids (RTILs) and ammonium pyrroldinedithiocarbamate (APDC) were used as enhancement reagents and chelating reagents for the CVG of lead, cadmium and bismuth, respectively. TS-FF-AAS was used for the determination of lead, cadmium and bismuth. The addition of RTILs led to an improvement of 3.5, 3.0 and 4.0 times the CVG efficiencies of Pb, Cd and Bi, respectively. The efficiencies for the CVG of Pb, Cd and Bi in the presence of RTILs and APDC were 55%, 46% and 60%, respectively. Volatile species of Pb, Cd and Bi were effectively generated through reduction of acidified analyte solutions with KBH4 in the presence of 0.02% (m/v) APDC and 0.1% (v/v) 1-butyl-3-methylimidazolium tetrafluoroborate ([C4MIM]BF4). Some parameters that influenced CVG and the subsequent determinations were evaluated in detail, such as the concentrations of RTILs, APDC, HNO3 and KBH4; the flow rates of the carrier gas, lengths of the reaction tube and transfer tube, as well as interferences. Under optimized conditions, the detection limits for Pb, Cd and Bi were 8, 1 and 5 ng mL−1, respectively. Relative standard deviations for five replicate determinations of a standard solution containing 200 ng mL−1 Pb, Cd and Bi were 4.5%, 5.5% and 5.2%, respectively. The proposed method was successfully applied in the determination of Pb, Cd and Bi in certified environmental reference materials with satisfactory results.
A novel method to preconcentrate gold was developed employing a synergistic enhancement of a room temperature ionic liquid combined with hollow fiber liquid phase micro-extraction with flame atomic absorption spectrometry detection. The method is based on the complexation of gold with dithizone. The formed hydrophobic complex was subsequently extracted into the lumen of a hollow fiber. The organic phase was siphoned into FAAS for the determination. A room temperature ionic liquid and dithizone were used the enhancement reagent and chelating reagent, respectively. The addition of a room temperature ionic liquid led to a five-fold improvement in the extraction of gold. The 1-octanol was immobilized in the pores of the polypropylene hollow fiber as the liquid membrane and was also used as the acceptor solution. Some parameters that influenced extraction and determination were evaluated in detail, such as concentrations of the ionic liquid and dithizone, pH of samples, stirring rates, extraction time, and interferences. Under optimized conditions, a detection limit of 0.9 ng mL−1 and an enrichment factor of 130 were achieved. The relative standard deviation (RSD) was 3.7% for Au (40 ng mL−1, n = 5). The proposed method was successfully applied to the determination of gold in certified reference environmental samples and ore samples with satisfactory results.
A new method based on chemical vapor generation (CVG) coupled with flame atomic absorption spectrometry (FAAS) was developed for the determination of iron, cobalt and nickel in environmental and biological samples. Room temperature ionic liquids (RTIL) combined with ammonium pyrroldinedithiocarbamate (APDC) were used to synergetically enhance the CVG of iron, cobalt and nickel. The addition of RTIL leads to 2.5, 3.2, 3.0 times improvement in the CVG efficiencies of Fe, Co and Ni, respectively. The efficiencies for the CVG of Fe, Co and Ni in the presence of RTIL and APDC were 42%, 61% and 54%, respectively. Volatile species of iron, cobalt and nickel were effectively generated through reduction of acidified analyte solutions with KBH4 in the presence of 0.02% or 0.01% (m/v) APDC and 0.1% or 0.2% (m/v) 1-butyl-3-methylimidazolium hexafluorophosphate ([C4MIM]PF6). Some parameters that influenced CVG and subsequent determination were evaluated in detail, such as the concentrations of RTIL, APDC, nitric acid (HNO3) and KBH4; flow rates of carrier gas, lengths of reaction tube and transfer tube, as well as interferences. Under optimized conditions, the detection limits (LODs) for Fe, Co and Ni were 18, 14 and 11 ng mL−1, respectively. Relative standard deviations for five replicate determinations of the standard solution containing 500 ng mL−1Fe, Co and Ni were 5.3%, 4.6% and 4.3%, respectively. The proposed method was successfully applied to the determination of iron, cobalt and nickel in certified environmental and biological reference materials with satisfactory results.
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