Simultaneous Preconcentration Of Trace Amounts Research Articles

Graphene oxide-packed micro-column solid-phase extraction combined with flame atomic absorption spectrometry for determination of lead (II) and nickel (II) in water samples

A sensitive and simple method has been established for simultaneous preconcentration of trace amounts of Pb (II) and Ni (II) ions in water samples prior to their determination by flame atomic absorption spectrometry. This method was based on the using of a micro-column filled with graphene oxide as an adsorbent. The influences of various analytical parameters such as solution pH, adsorbent amount, eluent type and volume, flow rates of sample and eluent, and matrix ions on the recoveries of the metal ions were investigated. Using the optimum conditions, the calibration graphs were linear in the range of 7–260 and 5–85 μg L−1 with detection limits (3Sb) of 2.1 and 1.4 μg L−1 for lead and nickel ions, respectively. The relative standard deviation for 10 replicate determinations of 50 μg L−1 of lead and nickel ions were 4.1% and 3.8%, respectively. The preconcentration factors were 102.5 and 95 for lead and nickel ions, respectively. The adsorption capacity of the adsorbent was also determined. The method was successfully applied to determine the trace amounts of Pb (II) and Ni (II) ions in real water samples. The validation of the method was also performed by the standard reference material.

CLOUD POINT EXTRACTION PROCEDURE FOR FLAME ATOMIC ABSORPTION SPECTROMETRIC DETERMINATION OF HEAVY METALS IN SURFACE SEDIMENTS OF CHAOHU LAKE, CHINA

A cloud point extraction (CPE) procedure for the simultaneous preconcentration of trace amounts of Cd(II), Pb(II), Cu(II), Co(II) and Ni(II) ions as a prior step to their determination by flame atomic absorption spectrometry (FAAS) has been developed. This developed method is based on the formation of hydrophobic complexes of these metals with the chelating agent 1-(2thiazolylazo)-2-naphthol (TAN), which then are entrapped in situ into micellar media of non ionic surfactant octylphenoxypolyethoxyethanol (Triton X-114). Several important variables that affect the complexation and extraction efficiency were investigated and the analytical characteristics of the method were obtained. The interference effect of some anions and cations was also tested. under the optimized conditions, the detection limits for three times the standard deviations of the blank were 1.12, 2.78, 0.77, 1.90 and 1.36 .g/L for Cd(II), Pb(II), Cu(II), Co(II) and Ni(II), respectively, were obtained. The proposed method has been successfully applied to the determination of metal ions in surface sediment samples with satisfactory results.

Potential of sawdust as a green and economical sorbent for simultaneous preconcentration of trace amounts of cadmium, cobalt, and lead from water, biological, food, and herbal samples.

Application of treated sawdust with NaOH as a green and economical sorbent for simultaneous preconcentration of trace amounts of Cd(II), Co(II), and Pb(II) ions from liver, lettuce, fish, and water as test samples with complicated matrices was investigated. Various parameters, such as effect of pH and contact time, breakthrough volume, type, and concentration of eluent and interference of ions were studied. The sorption was quantitative in the pH of 5.0 to 7.0 and desorption occurred instantaneously with 5.0mL of mixed solutions of ethanol and 2.0mol/L HNO3 -HCl and the amount of ions was measured by using flame atomic absorption spectrometry. Linearity was maintained at 3 to 500μg/L for cobalt, 5.0 to 800μg/L for lead, and 2.0 to 300μg/L for cadmium in the original solution. The relative standard deviation was less than 1.80% (n= 6, with concentration of 0.3mg/L for cadmium and 0.5mg/L for lead and cobalt). Detection limits and maximum capacity of the sorbent for Co (II), Cd (II), and Pb (II) in the original solution were 0.86, 0.50, and 1.7μg/L and 28.5, 30.6, and 47.3mg/g, respectively. The results for spiked real samples, effect of interfering ions, and adsorption capacity indicated that the applicability of this method for lead preconcentration is better than cadmium and cobalt preconcentration from complicated matrices. Practical Application: Sawdust can be applied as a green and economical sorbent for simultaneous preconcentration and solid-phase extraction of metal ions from food and environmental samples with complicated matrices.

SDS-coated Sepabeads SP70-modified by 4-[(E)-3-phenylallylidene) amino] benzenethiol as new efficient solid phase for enrichment and determination of copper, nickel, chromium, and zinc ions in soil, plants, and mint water samples

A sensitive and simple method based on modification of Sepabeads SP70 by 4-((E)-3-phenylallylidene) amino) benzenethiol for the simultaneous preconcentration of trace amounts of copper (Cu), nickel (Ni), chromium (Cr), and zinc (Zn) ions in some real samples has been reported. The metal ions which are retained as respective complexes on solid phase were eluted with 8 ml of 4 M nitric acid. The influences of different analytical parameters including pH, ligand amount and Sepabeads SP70 and SDS amount, eluting solutions, and sample volume on metal ions recoveries were investigated. The effects of matrix ions on the retentions of the analytes were also examined. The recoveries of analytes were generally >95% with RSD between 0.74 and 0.88. The proposed method has been successfully applied for the determination of these metals in some real samples with complex matrices.

Application of Dithizone-Modified TiO2 Nanoparticles in the Preconcentration of Trace Chromium and Lead from Sample Solution and Determination by Inductively Coupled Plasma Atomic Emission Spectrometry

A new method using dithizone-modified TiO2 nanoparticles (nanometer TiO2-DZ) as solid-phase extractant has been developed for the simultaneous preconcentration of trace amounts of chromium and lead prior to their measurement by inductively coupled plasma atomic emission spectrometry (ICP-AES). The preconcentration conditions of the analytes, including the effects of pH, sample flow rate and volume, elution conditions and interfering ions on the recovery of the analytes were investigated. At pH 5, the adsorption capacity of the nanometer TiO2-DZ was found to be 5.8 mg g−1 and 22.5 mg g−1 for Cr and Pb, respectively. According to the definition of IUPAC, the detection limits (3σ) of this method for Cr and Pb were 0.38 and 1.72 ng mL−1, respectively. The proposed method was applied to the determination of trace chromium and lead in foodstuffs, plants and water samples with satisfactory results.

Nanometer-size titanium dioxide microcolumn on-line preconcentration of trace metals and their determination by inductively coupled plasma atomic emission spectrometry in water

A new method using a microcolumn packed with nanometer TiO 2 as solid-phase extractant has been developed for the simultaneous preconcentration of trace amounts of Cu, Mn, Cr and Ni prior to their measurements by inductively coupled plasma atomic emission spectrometry (ICP-AES). Effects of pH, sample flow rate and volume, elution solution and interfering ions on the recovery of the analytes have been investigated. The adsorption capacity of nanometer TiO 2 was found as 0.108, 0.149, 0.039 and 0.034 mmol g −1 for Cu, Cr, Mn and Ni, respectively. The separation of analytes can be achieved from water samples with a concentration factor of 50 times. The method has been applied for the determination of trace elements in biological sample and lake water with satisfactory results.