University of North Florida
Browse the Citations
-OR-

Contact Info

Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Email: schalk@unf.edu
Website: @unf

View Stuart Chalk's profile on LinkedIn

Fullerene

Classification: Reagent -> Fullerene

Citations 4

"Speciation Of Inorganic Lead And Trialkyllead Compounds By Flame Atomic Absorption Spectrometry Following Continuous Selective Preconcentration From Aqueous Solutions"
Spectrochim. Acta B 1999 Volume 54, Issue 13 Pages 1869-1879
Josefa R. Baena, Mercedes Gallego and Miguel Valcárcel

Abstract: A new method for the speciation of inorganic lead and trialkyllead compounds involving the selective separation of the analytes in a continuous system and their subsequent introduction into a flame atomic absorption spectrometer was developed. The proposed flow system consists of two units. In the first unit, total inorganic lead at concentrations from 8 to 200 ng mL-1 is continuously precipitated as lead chromate and the filtrate, containing trialkyllead cations, is collected in a vessel, the precipitate then being dissolved in diluted acid and driven to the instrument. In the second unit, trimethyllead (TML+) and triethyllead (TEL+) cations at ng mL-1 levels are complexed with sodium diethyldithiocarbamate and retained on a C-60 pre-conditioned fullerene column; the mixture of both species was resolved by conditioning the sorbent column with n-hexane or isobutyl methyl ketone solvents. Detection limits of 1-2 ng mL-1 can be achieved by using a sample volume of 50 mL. Special attention was given to the reliability and robustness of the global flow injection method in assessing its applicability to both types of organolead compounds and inorganic lead present in different proportions. Trimethyllead provides the poorest results as consequence of its low adsorption constant on C-60; however, the three different types of species (Pb2+/TML+/TEL+) can be effectively determined in proportions from 1:1:1 to 30:12:1 with relative errors less than 10%.

"Speciation Of Inorganic Lead And Trialkyllead Compounds By Flame Atomic Absorption Spectrometry Following Continuous Selective Preconcentration From Aqueous Solutions"
Spectrochim. Acta B 1999 Volume 54, Issue 13 Pages 1869-1879
Josefa R. Baena, Mercedes Gallego and Miguel Valcárcel

Abstract: A new method for the speciation of inorganic lead and trialkyllead compounds involving the selective separation of the analytes in a continuous system and their subsequent introduction into a flame atomic absorption spectrometer was developed. The proposed flow system consists of two units. In the first unit, total inorganic lead at concentrations from 8 to 200 ng mL-1 is continuously precipitated as lead chromate and the filtrate, containing trialkyllead cations, is collected in a vessel, the precipitate then being dissolved in diluted acid and driven to the instrument. In the second unit, trimethyllead (TML+) and triethyllead (TEL+) cations at ng mL-1 levels are complexed with sodium diethyldithiocarbamate and retained on a C-60 pre-conditioned fullerene column; the mixture of both species was resolved by conditioning the sorbent column with n-hexane or isobutyl methyl ketone solvents. Detection limits of 1-2 ng mL-1 can be achieved by using a sample volume of 50 mL. Special attention was given to the reliability and robustness of the global flow injection method in assessing its applicability to both types of organolead compounds and inorganic lead present in different proportions. Trimethyllead provides the poorest results as consequence of its low adsorption constant on C-60; however, the three different types of species (Pb2+/TML+/TEL+) can be effectively determined in proportions from 1:1:1 to 30:12:1 with relative errors less than 10%.

"Online Separation And Preconcentration Of Cadmium, Lead And Nickel In A Fullerene (C60) Minicolumn Coupled To Flow Injection Tungsten Coil Atomic Absorption Spectrometry"
Anal. Chim. Acta 1998 Volume 368, Issue 3 Pages 255-263
Marcia M. Silvaa, Marco A. Z. Arrudab, Francisco J. Kruga,*, Pedro V. Oliveirac, Zilvanir F. Queiroza, Mercedes Gallegod and Miguel Valcárceld

Abstract: A flow system was coupled to a W coil electrothermal atomizer (150 W) for online separation and pre-concentration of Cd, lead and Ni based on the formation of DDC complexes and sorption into a minicolumn packed with fullerene C60. Three way solenoid valves used for sample and reagents management as well as the W coil power supply were controlled by a computer running a program written in Visual Basic, which was employed in synchronism with the original software of the atomic absorption spectrometer. The fullerene column (5 mm length, 2 mm internal diameter) was inserted into the tip of the autosampler arm, and elution was performed by sampling 35 µL of MeOH from the autosampler cup. With 3.0 mL of sample (loading time of 60 s) enrichment factors ranging from 100 to 150 were achieved. The detection limits for Cd, lead and Ni were 2.2, 23 and 75 ng L-1, respectively. No interference effects were observed on Cd, lead and Ni pre-concentration in the presence of up to 106 fold concentrations of Na, K, Ca or Mg. Application of t-test to the results obtained by the proposed method and the certified values of Cd, lead and Ni in five water reference materials did not reveal significant differences at the 5% probability level.
Cadmium Lead Nickel Environmental Blood Spectrophotometry

"Preconcentration Of Copper Traces On C60-C70 Fullerenes By Formation Of Ion Pairs And Chelates"
Anal. Chem. 1995 Volume 67, Issue 15 Pages 2524-2529
Yaneira Petit de Pena, Mercedes Gallego, and Miguel Valcarcel

Abstract: Solutions of copper(II) nitrate containing 1-125 ng/ml Cu(II) of pH 4 were pumped through a flow injection manifold (illustrated) and mixed with a carrier solution (described) to give bis[(2,9-dimethyl-1,10-phenanthroline)Cu(I)]-SDS, (I), bis[(1,10-phenanthroline)Cu(II)]-SDS2, (II), [tetrakis(thiocyanato)Cu(I)]-(dodecyltrimethylammonium bromide)3 (III) or pyrrolidinedithiocarbamate-Cu(II) chelate (IV). Hydroxylamine hydrochloride was added to Cu(II) solutions to promote the formation of Cu(I) ion-pairs or chelates I and III. The latter or II and IV were adsorbed on C60 (>99.4%) or C60/C70 (~e;17:3) fullerenes contained in micro-columns (described). Complexes were desorbed with MIBK and analyzed by AAS at 324.7 nm. Calibration graphs were linear for 5-80 ng/ml, 3-60 ng/ml, 7-125 ng/ml and 1-30 ng/ml of Cu complexed as I-IV respectively, pre-concentrated on C60 fullerenes. The corresponding detection limits and RSD were 2, 1, 3 and 0.5 ng/ml and 2.2, 3, 2 and 1.9%. Similar analyzes were obtained with pre-concentration on C60/C70 (17:3). The effects of foreign ions are discussed.
Copper(II) Spectrophotometry