Determination of cadmium and lead in table salt by sequential multi-element flame atomic absorption spectrometry
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.
- "Consequently, cadmium removal has been given great priority in the last decade (Lu and Yan 2004; Lemos and. Baliza, 2005; Fang et al., 2005; Amorim et al., 2005; Davis et al., 2006). Owing to the co-existence of various heavy metal ions in industrial effluents or other water resources, selective removal of toxic metal ions attracts much attention in both industries and researches. "
[Show abstract] [Hide abstract] 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.0Comments 3Citations
- "In Brazil, cadmium content of salts was 0.01-0.03 μg/g , 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 . "
[Show abstract] [Hide abstract] ABSTRACT: Aims: In this study, the heavy metal contamination of consumable table salt, both unrefined and refined, was investigated. The provisional tolerable weekly intake (PTWI) of heavy metals just by edible salt, of the Isfahan population, was also estimated. Materials and Methods: Twenty samples of salt, including 15 refined and five unrefined were analyzed. Precision of the analysis was assured through repeated analysis of the five samples, which had a great demand in the city. The heavy metal content in the samples was analyzed with Flame Atomic Absorption Spectrometry (AAS) and Inductively Coupled Plasma (ICP). The PTWI of the metals was calculated by a formula and by using the Iranian average body weight. Results: The mean and standard deviations of cadmium (Cd), lead (Pb), arsenic (As), mercury (Hg), copper (Cu), and zinc (Zn), in refined table salts were 0.15 ± 0.02, 0.57 ± 0.1, 0.69 ± 0.09, 0.061 ± 0.008, 0.87 ± 0.11, and 6.34 ± 1.08 µg/g, and those in the unrefined ones were 0.16 ± 0.02, 0.61 ± 0.13, 0.63 ± 0.07, 0.058 ± 0.004, 0.86 ± 0.06, and 7.53 ± 2.93 µg/g, respectively. A PTWI via salt consumption was in the range of 0.8 – 3.1 percent. Conclusions: There was a significant difference between the heavy metal concentrations and their guideline values. Estimation of the health risk due to heavy metals was not possible as PTWI showed total intake of a metal by total food consumption during a week. Therefore, it was important to assess the public health risks arising from the presence of these toxic contaminants in the foods consumed by the population of Iran.0Comments 9Citations
- "µg/g,  and 0.024 µg/g.  Lead level was found to be in the range of 0.386 – 0.853 µg/g, which was lower than the guidelines. However, the average of its concentration in the refined salts was slightly higher than that in the unrefined ones [18,19] (P value <0.001). Amorim et al. reported that the lead content of the salts was up to 0.106 µg/g.  In Tehran salt it was reported to be in the range of 0.87 – 1.6 µg/g  and 0.438 µg/g.  The arsenic and mercury levels of the investigated salts were in the range of 0.511 – 0.894 µg/g and 0.05 – 0.08 µg/g, respectively. Their highest level was found in a refined sample, however, its mean concentration was lower than the guidelines"