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: 3.55). 03/2005; 65(4):960-4. DOI: 10.1016/j.talanta.2004.08.027
Source: PubMed


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.

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    • "In Brazil, cadmium content of salts was 0.01-0.03 μg/g [31], and in a study by Soylak et al., it was 0.014-0.030 μg/g in refined and unrefined table salt samples from Turkey, Egypt and Greece [30]. "
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    ABSTRACT: Table salt is the most commonly used food additive. Since most of the salt consumed in Iran comes from mines, contamination with heavy metals is a health concern. The commonest salt purification method in Iran is washing with water. But recently, some industries have turned to recrystallization method. The present study aimed to determine the level of essential and non-essential heavy metals in the table salt refined with recrystallization and washing methods. Thirty eight pre-packed salt samples were directly collected from retail market in Shiraz (22 samples refined with recrystallization method and 16 with washing method). The level of lead, cadmium, copper, zinc, nickel and cobalt was determined using Voltammetric method. Daily intakes of lead and cadmium as well as their weekly intakes were calculated. The levels of lead, cadmium, copper, zinc, nickel and cobalt in recrystallized samples were 0. 30 +/- 0.26, 0.02 +/- 0.02, 0.11 +/- 0.06, 0.34 +/- 0.22, 0.15 +/- 0.19 and 0.008 +/- 0.007 mug/g, respectively, and also 0.37 +/- 0.27, 0.017 +/- 0.021, 0.19 +/- 0.18, 0.37 +/- 0.20, 0.13 +/- 0.23 and 0.037 +/- 0.06 mug/g in washed salt samples. The calculated weekly intake of lead and cadmium was 0.216 and 0.014 mug /kg, respectively for the recrystallized and 0.2653 and 0.0119 mug/kg for the washed salts. All values for toxic metals were lower than the permitted maximum for human consumption as prescribed by Codex and Institute of Standards and Industrial Research of Iran. Only 0.8652-1.0612% of lead and 0.17-0.2% of cadmium PTWIs are received via salt consumption weekly.
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    • "Therefore, due to the daily consumption of table salt, any contamination in salt even in low level could create health risks to the consumers. Recently, incidence of heavy metal contamination in table salt has been investigated worldwide (1-5). "
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    ABSTRACT: Lead, cadmium, mercury and arsenic are the most important heavy metals which may cause health risks following consumption of contaminated foods. Table salt is one the mostly used food additive with unique place in food consumption. Although purified table salt is expected to have lower level of contamination, some Iranians still prefer to use rock salt. Use of rock salt for food purposes has been banned by Iranian health authorities. In this study, heavy metal contamination of table salt consumed in Iran has been investigated. One hundred samples of rock and refined table salts were analyzed using atomic absorption spectrophotometeric methods for the presence of toxic heavy metals. The mean concentration of tested tracer metals including Cd, Pb, Hg and As was 0.024, 0.438, 0.021 and 0.094 μg/g, respectively. The concentrations of tested heavy metals were well below the maximum levels set by Codex. However, no statistically significant difference was found between contamination of rock salt and refined salt to heavy metals.
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    ABSTRACT: A novel manganese dioxide (MnO2) resin is suitable for the determination and decontamination of lead isotopes (208Pb, 207Pb, 206Pb) in aqueous solutions at trace concentrations. This is desirable due to the toxic nature and high abundance of lead in the environment. Current techniques are both time consuming, expensive and not suitable for low-level lead decontamination. The MnO2 resin has been demonstrated to pre-concentrate with extraction efficiency above 90% for a range of pH values, and with a mean extraction of 92.5% from fresh waters at a flow rate of 100 ml min−1. The lead distribution coefficient is 1.3 × 104 (pH 7) with tolerance to calcium and sodium. Adsorption isotherms have been investigated and the resin shown to follow the Langmuir adsorption isotherm with a saturation point of 41.5 mg per g of MnO2 resin.
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