Simultaneous pre-concentration of Pb and Sn in food samples and determination by atomic absorption spectrometry (original) (raw)
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Food chemistry, 2015
A relatively rapid, accurate and precise solid phase extraction method is presented for the determination of cadmium(II) and lead(II) in various food and water samples. Quantitation is carried out by flame atomic absorption spectrometry (FAAS). The method is based on the retention of the trace metal ions on Dowex Marathon C, a strong acid cation exchange resin. Some important parameters affecting the analytical performance of the method such as pH, flow rate and volume of the sample solution; type, concentration, volume, flow rate of the eluent; and matrix effects on the retention of the metal ions were investigated. Common coexisting ions did not interfere on the separation and determination of the analytes. The detection limits (3σb) for Cd(II) and Pb(II) were found as 0.13 and 0.18μgL(-1), respectively, while the limit of quantification values (10σb) were computed as 0.43 and 0.60μgL(-1) for the same sequence of the analytes. The precision (as relative standard deviation was lowe...
Journal of the Iranian Chemical Society, 2018
This paper established a new, rapid and sensitive method for the ultra-trace determination of lead, cadmium and nickel in food and environmental samples preconcentrated by dispersive solid-phase extraction (DSPE) combined with surfactant-assisted dispersive liquid-liquid microextraction (SA-DLLME) prior to graphite furnace atomic absorption spectrometry. SBA-15/Met was synthesized and used as a new efficient sorbent for the extraction of metal ions in DSPE. It was characterized by TEM and TGA techniques. After DSPE step, stripped metal elements were complexed with dithizone, and then, the complexes were extracted into carbon tetrachloride by using SA-DLLME. A conventional nonionic surfactant, triton X-100 was used as a disperser agent. Under the optimized conditions, the limit of quantifications was found to be 2.5 ng L −1 for Pb 2+ , Cd 2+ and 5.0 ng L −1 for Ni 2+. The limits of detection were 1.5 ng L −1 for Ni 2+ and 0.75 ng L −1 for Pb 2+ and Cd 2+ , with enrichment factor of 1650. The optimized method exhibited a good precision level with relative standard deviations (RSDs%) values of 4.9, 5.2 and 5.0% for 1 μg L −1 Pb 2+ , Cd 2+ and Ni 2+ , respectively (n = 7). Application of the proposed method to the analysis of fish-certified reference material produced results that were in good agreement with the certified values.
Arabian Journal of Chemistry, 2011
A sensitive cloud point extraction procedure(CPE) for the preconcentration of trace lead prior to its determination by flame atomic absorption spectrometry (FAAS) has been developed. The CPE method is based on the complex of Pb(II) ion with 1-(2-pyridylazo)-2-naphthol (PAN), and then entrapped in the non-ionic surfactant Triton X-114. The main factors affecting CPE efficiency, such as pH of sample solution, concentration of PAN and Triton X-114, equilibration temperature and time, were investigated in detail. A preconcentration factor of 30 was obtained for the preconcentration of Pb(II) ion with 15.0 mL solution. Under the optimal conditions, the calibration curve was linear in the range of 7.5 ng mL À1 -3.5 lg mL À1 of lead with R 2 = 0.9998 (n = 10). Detection limit based on three times the standard deviation of the blank (3S b ) was 5.27 ng mL À1 . Eight replicate determinations of 1.0 lg mL À1 lead gave a mean absorbance of 0.275 with a relative standard deviation of 1.6%. The high efficiency of cloud point extraction to carry out the determination of analytes in complex matrices was demonstrated.
Analytica Chimica Acta, 2000
A method for the simultaneous determination of cadmium and lead in foodstuffs by electrothermal atomic absorption spectrometry (ETAAS) with a transversely heated graphite atomizer (THGA) and Zeeman-effect background corrector is proposed. The samples (0.500 g) were digested to clear solutions with 5.0 ml concentrated nitric acid in a closed vessel microwave oven. Among various chemical modifiers tested, the best recovery and repeatability results were obtained with a 0.5% (w/v) NH 4 H 2 PO 4 + 0.03% (w/v) Mg(NO 3) 2 mixture. The pyrolysis and atomization temperatures for the simultaneous determination of cadmium and lead were 750 and 1600 • C, respectively. Tests carried out with several individual concomitants were performed and did not reveal significant interference on cadmium and lead atomization. Characteristic masses were 1.46 pg for cadmium (RSD = 4.0%) with 8.0% for reproducibility and 36.7 pg for lead (RSD = 2.6%) with 2.0% for reproducibility. The detection limits obtained were 0.38 pg (n = 20, 3δ) for cadmium and 9.3 pg (n = 20, 3δ) for lead. The relative standard deviations based on five measurements for each of the reference solutions (0.25-4.0 g Cd 2+ l −1) and (2.5-40 g Pb 2+ l −1) were always lower than 6.0%. The reliability of the entire procedure was confirmed by spike-tests or analysis of certified reference material (CRM) as spinach (No. 1570a) and bovine liver (No. 1577b) from NIST.
Journal of Hazardous Materials, 2011
The phase-separation phenomenon of non-ionic surfactants occurring in aqueous solution was used for the extraction of lead (Pb 2+ ) from digested blood samples after simultaneous complexation with ammonium pyrrolidinedithiocarbamate (APDC) and diethyldithiocarbamate (DDTC) separately. The complexed analyte was quantitatively extracted with octylphenoxypolyethoxyethanol (Triton X-114). The multivariate strategy was applied to estimate the optimum values of experimental factors. Acidic ethanol was added to the surfactant-rich phase prior to its analysis by flame atomic absorption spectrometer (FAAS). The detection limit value of Pb 2+ for the preconcentration of 10 mL of acid digested blood sample was 1.14 g L −1 . The accuracy of the proposed methods was assessed by analyzing certified reference material (whole blood). Under the optimized conditions of both CPE methods, 10 mL of Pb 2+ standards (10 g L −1 ) complexed with APDC and DDTC, permitted the enhancement factors of 56 and 42, respectively. The proposed method was used for determination of Pb 2+ in blood samples of children with kidney disorders and healthy controls.
A cloud point extraction (CPE) method was developed for the separation and preconcentration of trace amounts of lead is combined with flame atomic absorption spectrometry (FAAS) to determine trace amounts of lead in brine water. The method is depended on the formation of the hydrophobic complex between Pb(II) and (APDC) followed by its extraction into a Triton X-114 using surfactant. The parameters such as pH of sample, concentrations ofAPDC and Triton X-114, equilibrium temperature, and equilibrium time, which affect both complexation and extraction, are optimized. Under the selected optimum conditions, and use of matrix modifying agents enable us to develop the direct method for determination Pb in brine water. The accuracy of the method was % (96)while the detection limit was found to be (0.1122 ppm) for preconcentration of 1.0 ml sample,for the determination of Pb(II) is obtained.
Applied Sciences, 2019
The cloud point extraction (CPE) method was successfully used for the isolation and pre-concentration of ultra-low concentration of Pb prior to its determination by flame atomic absorption spectrometry (FAAS). Lead(II) reacts with methyl 4,20-diisobutyl-2,5,8,16,19,22- hexaoxo-7,17-dipropyl-3,6,9,15,18,21-hexaaza-1(2,6)-pyridinacyclo-docosaphane-10-carboxylate (DLNL) as chelating agent in the presence of octylphenoxypolyethoxyethanol (Triton X-114) as a nonionic surfactant giving a surfactant-rich phase chelate which could be used for CPE. Factors affecting the CPE such as solution pH, concentrations of the chelating ligand and surfactant, temperature of equilibration, and time were optimized. The efficacy features of the proposed protocol such as linear range, lower limit of detection, pre-concentration, and progress factors were evaluated. The method revealed a wide linear range in the range of 7–250 ng/mL of Pb2+ with a limit of detection of 5 ng/mL using FAAS. Validation of the ...
CLEAN - Soil, Air, Water, 2009
The phase-separation phenomenon of non-ionic surfactants occurring in aqueous solution was used for the extraction of lead(II) and zinc(II). After complexation with 3-[(4bromophenyl) (1-H-inden-3-yl)methyl]-1 H-indene (BPIMI), the analytes were quantitatively extracted to a phase rich in Triton X-114 after centrifugation. Methanol acidified with 1 mol/L HNO 3 was added to the surfactant rich phase prior to its analysis by flame atomic absorption spectrometry (FAAS). The concentration of bis((1H-benzo [d] imidazol-2yl)ethyl)sulfane, Triton X-114, pH and amount of surfactant were all optimized. Detection limits (3 SDb/m) of 2.5 and 1.6 ng/mL for Pb 2+ and Zn 2+ along with preconcentration factors of 30 and an enrichment factor of 32 and 48 for Pb 2+ and Zn 2+ ions were obtained, respectively. The proposed cloud point extraction was been successfully applied for the determination of these ions in real samples with complicated matrices such as food and soil samples, with high efficiency.