Determination of cadmium and lead in table salt by sequential multi-element flame atomic absorption spectrometry.

Instituto de Química, Núcleo de Excelência em Química Analítica da Bahia, Grupo de Pesquisa em Química Analítica, Universidade Federal da Bahia, Campus Universitário de Ondina, Salvador 40170-290, Bahia, Brazil.
Talanta (Impact Factor: 3.5). 03/2005; 65(4):960-4. DOI: 10.1016/j.talanta.2004.08.027
Source: PubMed

ABSTRACT In the present paper, a simultaneous pre-concentration procedure for the sequential determination of cadmium and lead in table salt samples using flame atomic absorption spectrometry is proposed. This method is based on the liquid-liquid extraction of cadmium(II) and lead(II) ions as dithizone complexes and direct aspiration of the organic phase for the spectrometer. The sequential determination of cadmium and lead is possible using a computer program. The optimization step was performed by a two-level fractional factorial design involving the variables: pH, dithizone mass, shaking time after addition of dithizone and shaking time after addition of solvent. In the studied levels these variables are not significant. The experimental conditions established propose a sample volume of 250mL and the extraction process using 4.0mL of methyl isobutyl ketone. This way, the procedure allows determination of cadmium and lead in table salt samples with a pre-concentration factor higher than 80, and detection limits of 0.3ngg(-1) for cadmium and 4.2ngg(-1) for lead. The precision expressed as relative standard deviation (n = 10) were 5.6 and 2.6% for cadmium concentration of 2 and 20ngg(-1), respectively, and of 3.2 and 1.1% for lead concentration of 20 and 200ngg(-1), respectively. Recoveries of cadmium and lead in several samples, measured by standard addition technique, proved also that this procedure is not affected by the matrix and can be applied satisfactorily for the determination of cadmium and lead in saline samples. The method was applied for the evaluation of the concentration of cadmium and lead in table salt samples consumed in Salvador City, Bahia, Brazil.

  • [Show abstract] [Hide abstract]
    ABSTRACT: We demonstrate the application of an ionic liquid-based ferrofluid to the dispersive solid phase extraction of lead(II) using PAN as the chelator. The ionic liquid contains silica nanoparticles with a magnetic core as the dispersion medium, and its use results in improved stability of the colloidal dispersion and a complete extraction of lead(II) within a few seconds. In addition, there is no need for centrifugation. Specifically, the effect of different variables on the extraction of lead(II) was studied using an experimental design. Lead(II) was quantified by AAS. Under optimized conditions, the calibration graph for lead(II) is linear in the range from 5 to 372 mu g L-1, the relative standard deviation is 1.34 % (for n = 7), the limit of detection is 1.66 mu g L-1, and the enrichment factor is 200. The maximum adsorption capacity of sorbent was calculated to be 10.7 mg g(-1), and adsorption follows a Langmuir isotherm.
    Microchimica Acta 11/2014; 181(15-16):1833-1841. DOI:10.1007/s00604-014-1254-1 · 3.72 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We report on a new sorbent for preconcentration of cadmium and lead ions that is based on triazine-functionalized magnetite nanoparticles that were prepared by direct silylation of magnetic nanoparticles with 3-aminopropyltriethoxysilane-2,4-bis(3,5-dimethylpyrazol)-triazine. The sorbent was characterized by IR spectroscopy, X-ray powder diffraction, scanning electron microscopy, thermal and elemental analysis. The sorbent was applied to the preconcentration of lead and cadmium ions which then were quantified by FAAS. The effects of sample pH value, extraction time, of type, concentration and volume of eluent, and of elution time were optimized. The limits of detection are 0.7 ng mL(-1) for Pb(II) ion and 0.01 ng mL(-1) for Cd(II). The effects of potentially interfering ions often found in real samples on the recovery in the determination of cadmium and lead ions in real samples were also investigated. The accuracy of the method was confirmed by analyzing the certified reference materials NIST 1571 (orchard leaves) and NIST 1572 (citrus leaves). Finally, the method was successfully applied to the determination of cadmium and lead ions in some fruit samples.
    Microchimica Acta 11/2014; 181(15-16):1781-1788. DOI:10.1007/s00604-014-1223-8 · 3.72 Impact Factor
  • Source