The present paper proposes an on-line preconcentration procedure for lead determination in Ilex paraguariensis (St. Hilaire) samples by ultrasonic nebulization associated to inductively coupled plasma optical emission spectrometry (USN-ICP-OES). It is based on the precipitation of lead(II) ion on a minicolumn packed with polyurethane foam using 2-(5-bromo-2-pyridilazo)-5-diethylaminophenol (5-Br-PADAP) as precipitating reagent. The collected analyte precipitate was quantitatively eluted from the minicolumn with 20% (v/v) nitric acid. An enhancement factor of 225-fold was obtained (15 for USN and 15 for preconcentration). The detection limit (DL) value for the preconcentration of 10.0 ml of sample was 40.0 ng/l. The relative standard deviation (R.S.D.) was 3.0% for a Pb concentration of 1 microg/l, calculated from the peak heights obtained. The calibration graph using the preconcentration system for lead was linear with a correlation coefficient of 0.9997, at levels near the detection limits up to at least 100 microg/l. The preconcentration procedure was successfully applied to the determination of lead in mate tea samples.
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"These authors found high concentration of B and higher Mn concentration than those in other plants used for infusion. According to Marchisio et al. (2005), pre-concentration of Pb was necessary for its *Corresponding author. Email: firstname.lastname@example.org "
[Show abstract][Hide abstract] ABSTRACT: Toxic and nutrient elements were investigated in yerba mate (Ilex paraguariensis) from South America. Fifty-four brands of commercialized yerba mate from Argentina, Brazil, Paraguay and Uruguay were analyzed for Al, Ba, Ca, Cu, Fe, K, Mg, Mn, P, Sr, and Zn, using inductively coupled plasma optical emission spectrometry (ICP-OES), and Li, Be, Ti, V, Cr, Ni, Co, As, Se, Rb, Mo, Ag, Cd, Sb, La, Ce, Pb, Bi and U using inductively coupled plasma mass spectrometry (ICP-MS). Antimony, Se, Ag and Bi were not detected in any sample whereas the limits of detection (LODs) of these elements were 0.19, 0.40, 0.003 and 0.001 g g(-1), respectively. Analysis of variance (ANOVA) revealed that the concentrations of Cd, Ti, Ni, As, Mo, U, Li and Be in yerba mate were not statistically different regarding to country of origin, while those of the other investigated elements differed.
Full-text · Article · Jun 2015 · Food Additives and Contaminants: Part B Surveillance
[Show abstract][Hide abstract] ABSTRACT: The concentrations of copper, manganese, zinc, iron and aluminum in commercial powdered soup samples produced in Turkey were determined using flame and graphite furnace atomic absorption spectrometry. We compared wet, dry and microwave digestion procedures for the digestion of the soup samples. The microwave digestion procedure for the soup samples was demonstrated to be most effective due to its simplicity and quick results. The accuracy of the method was checked against a standard reference material (SRM 8418 Wheat Gluten). Contents of investigated trace metals in soup samples ranged between 0.41 and 4.78 μg/g for copper, 1.29 and 49.4 μg/g for manganese, 1.26 and 22.5 μg/g for zinc, 4.62 and 61.7 μg/g for iron, and 6.86 and 547.7 μg/g for aluminum. The results were compared with values reported in the literature.
Full-text · Article · Mar 2006 · Journal of Food and Drug Analysis
[Show abstract][Hide abstract] ABSTRACT: The first publication on the use of polyurethane foam (PUF) for sorption processes dates back to 1970, and soon after the material was applied for separation processes. The application of PUF as a sorbent for solid phase extraction of inorganic analytes for separation and pre-concentration purposes is reviewed. The physical and chemical characteristics of PUF (polyether and polyester type) are discussed and an introduction to the characterization of these sorption processes using different types of isotherms is given. Separation and pre-concentration methods using unloaded and loaded PUF in batch and on-line procedures with continuous flow and flow injection systems are presented. Methods for the direct solid sampling analysis of the PUF after pre-concentration are discussed as well as approaches for speciation analysis. Thermodynamic proprieties of some extraction processes are evaluated and the interpretation of determined parameters, such as enthalpy, entropy and Gibbs free energy in light of the physico-chemical processes is explained.
Full-text · Article · Jan 2007 · Spectrochimica Acta Part B Atomic Spectroscopy