Jingci Li

Graphene-based solid-phase extraction combined with flame atomic absorption spectrometry for a sensitive determination of trace amounts of lead in environmental water and vegetable samples

Graphene, a novel class of carbon nanostructures, has great promise for use as sorbent materials because of its ultrahigh specific surface area. A new method using a column packed with graphene as sorbent was developed for the preconcentration of trace amounts of lead (Pb) using dithizone as chelating reagent prior to its determination by flame atomic absorption spectrometry. Some effective parameters on the extraction and complex formation were selected and optimized. Under optimum conditions, the calibration graph was linear in the concentration range of 10.0-600.0 μg L(-1) with a detection limit of 0.61 μg L(-1). The relative standard deviation for ten replicate measurements of 20.0 and 400.0 μg L(-1) of Pb were 3.56 and 3.25%, respectively. Comparative studies showed that graphene is superior to other adsorbents including C18 silica, graphitic carbon, and single- and multi-walled carbon nanotubes for the extraction of Pb. The proposed method was successfully applied in the analysis of environmental water and vegetable samples. Good spiked recoveries over the range of 95.3-100.4% were obtained. This work not only proposes a useful method for sample preconcentration, but also reveals the great potential of graphene as an excellent sorbent material in analytical processes.

Application of graphene as a sorbent for preconcentration and determination of trace amounts of chromium(III) in water samples by flame atomic absorption spectrometry

Graphene, a novel class of carbon nanostructure, has great promise for use as a sorbent material because of its ultrahigh specific surface area. A new method using a column packed with graphene as sorbent is developed for the preconcentration of trace amounts of chromium(III) prior to its determination by flame atomic absorption spectrometry. Some effective parameters on the extraction and complex formation were selected and optimized. The optimum experimental conditions of the proposed method were: pH, 8.0; amount of chelating agent, 2.0 mL of 0.1 mol L−1 8-hydroxyquinoline solution; eluent type and its volume, 2.0 mL of 2.0 mol L−1 nitric acid; flow rates of sample and eluent solution, 2.0 mL min−1. Under optimum conditions, an enrichment factor of 125 was obtained. The calibration graph was linear in the concentration range of 10.0–1000.0 μg L−1 with a correlation coefficient of 0.9995. The detection and quantification limits were 0.5 and 1.6 μg L−1, respectively. The relative standard deviation for ten replicate measurements were 4.3% for 20.0 μg L−1 and 3.4% for 800.0 μg L−1 of Cr(III). The proposed method was applied to tap water, sea water, and river water, and its accuracy was assessed through the analysis of certified reference water and recovery experiments. The recoveries of spiked samples were in the range of 95.7–101.2%.

Ultrasound-assisted emulsification solidified floating organic drop microextraction for the determination of trace cadmium in water samples by flame atomic absorption spectrometry

A liquid-phase microextraction technique was developed using ultrasound-assisted emulsification solidified floating organic drop microextraction (USAE-SFODME) combined with flame atomic absorption spectrometry (FAAS) for the extraction and determination of trace cadmium in water samples. Microextraction efficiency factors, such as extraction solvent type and extraction volume, time, temperature, pH, the amount of the chelating agent, and salt effect, were investigated and optimized. Under optimum conditions, an enrichment factor of 81.0 was obtained for 6.0 mL of water sample. The calibration graph was linear in the range of 10-450 mg L-1 with a detection limit of 0.66 µg L-1. The relative standard deviations (RSD) for ten replicate measurements of 20 and 300 µg L-1 of Cd were 3.34% and 2.42%, respectively. The accuracy of the proposed method was assessed either by determination of Cd in a certified reference material of water or by addition-recovery experiments

A Green and Efficient Synthesis of 9-Aryl-3,4,5,6,7,9-hexahydroxanthene-1,8-dione using a Task-Specific Ionic Liquid as Dual Catalyst and Solvent

A green and efficient method for the preparation of 9-aryl-3,4,5,6,7,9-hexahydro-1H-xanthene-1,8(2H)-dione has been developed using functionalized ionic liquids as a catalyst and a reaction medium. The nature of both the counter anion and cation influence the catalytic performance of the ionic liquids. The ionic liquid can be recycled and reused without apparently loss of activity.

Solid-Phase Extraction Clean-up Combined with Solidified Floating Organic Drop Microextraction for the Determination of Trace Manganese(II) in Different Environmental Matrices

Abstract Solid-phase extraction (SPE) clean-up combined with solidified floating organic drop microextraction (SFODME) has been developed as a new approach for the extraction and determination of trace manganese(II) in environmental water and vegetable samples. After purification of the samples by a graphene-packed SPE cartridge, SFODME technique was performed on the obtained solution. The main parameters affecting the performance of SFODME, such as type of extraction solvent as well as extraction volume, time, temperature, pH, the amount of the chelating agent, and salt effect were investigated and optimized. Under optimum conditions, a preconcentration factor of 81.0 was obtained from 7.0 mL of sample solution. The calibration graph was linear in the range from 1.90 to 400 μg/L with a detection limit of 0.57 μg/L. The relative standard deviation for ten replicate measurements of 10 and 300 μg/L of manganese(II) were 3.57 and 2.63 %, respectively. The proposed method was applied to tap, sea, river, and vegetable samples, and its accuracy was assessed through the analysis of certified reference water and recovery experiments.

Graphene-Based Solid-Phase Extraction for a Sensitive Determination of Trace Amounts of Lead in Water Samples

Abstract Graphene, a novel class of carbon nanostructures, has great promise for use as sorbent materials because of its ultrahigh specific surface area. A new method using a column packed with gaphene as sorbent was developed for the preconcentration of trace amounts of lead (Pb) prior to its determination by flame atomic absorption spectrometry. Some effective parameters on the extraction and complex formation were selected and optimized. Under optimum conditions, an enrichment factor of 250 was obtained. The calibration graph was linear in the concentration range of 2.4x 10.8 mol L-1-2.9x 10.6 mol L-1 with a detection limit of 1.9x 10.9 mol L-1. The relative standard deviation for ten replicate measurements of 9.7x 10.8 mol L-1 and 1.4x 10.6 mol L-1 of Pb were 3.45 %and 3.28 %, respectively. The proposed method was successfully applied in the analysis of four real environmental water samples and good spiked recoveries over the range of 95.5–99.6 %were obtained. This work not only proposes a useful method for environmental water sample pretreatment, but also reveals the great potential of gaphene as an excellent sorbent material in analytical processes.