Abstract
A new sensitive and accurate solid-phase extraction method for preconcentration of trace amounts of cadmium and lead in various environmental samples prior to flame atomic absorption spectrometry determination has been developed. The proposed method is based on the utilization of multiwalled carbon nanotubes in combination with 5-benzyl-4-[-chlororbenzylidene amine]-4H-1,2,4-triazole-3-thiol (BCBATT) as a solid-phase sorbent with the aid of ultrasonication. The effect of the preconcentration parameters was investigated. Good recoveries ranging from 95% to 102% with relative standard deviations of 3.2% and 2.8% for Cd$^{2+}$ and Pb$^{2+}$, respectively, were obtained, indicating high accuracy and precision. The limits of detection were 0.2 and 0.5 $\mu $g/L for Cd$^{2+}$ and Pb$^{2+}$, respectively. The preconcentration factor was 100. The validation of the proposed preconcentration procedure was performed using certified reference materials with satisfactory and compatible results. The proposed method was applied to various real environmental samples for determination of Cd$^{2+}$ and Pb$^{2+}$ concentrations and satisfactory results were obtained.
Highlights
In environmental samples, heavy metals are considered to be hazardous materials due to their toxicity for animals and humans even at low concentration levels. 1 Trace levels of cadmium and lead metals have acute and chronic effects on humans and other living organisms when accumulated in various tissues and can cause harmful gastrointestinal, cardiovascular, hematological, renal, kidney, and reproductive effects
The determination of trace levels of Cd 2+ and Pb 2+ ions as important heavy metals in environmental samples is a very significant goal for chemists working in the fields of analytical chemistry and environmental analytical chemistry. 2−4 Flame atomic absorption spectrometry (FAAS) has been widely used for estimation of heavy metals in environmental samples. 5,6 trace quantities of analytes lower than the limit of detection of FAAS and the coexisting ions’ interference are two limitations in FAAS estimations
The use of multiwalled carbon nanotubes (MWCNTs) as Solid-phase extraction (SPE) sorbents to preconcentrate trace levels of metal ions is a relatively significant field of environmental analytical chemistry. 27,28 MWCNT surfaces may be filled with a number of ligands to promote adsorption capability and functionality, and a suitable chelating agent is generally necessary. 28−40 The elution of the analytes and the choice of the eluting solvent is the final stage of SPE for obtaining a significant enrichment factor and high recovery of adsorbed metal ions on MWCNTs
Summary
Heavy metals are considered to be hazardous materials due to their toxicity for animals and humans even at low concentration levels. 1 Trace levels of cadmium and lead metals have acute and chronic effects on humans and other living organisms when accumulated in various tissues and can cause harmful gastrointestinal, cardiovascular, hematological, renal, kidney, and reproductive effects. Solid-phase extraction (SPE) is an important and widespread method for the separation and preconcentration of trace quantities of metal ions in environmental samples with complex matrices because of its notable advantages, such as speed, simplicity, low cost, reusability of the adsorbent, and environmentally friendly and high enrichment factors. 28−40 The elution of the analytes and the choice of the eluting solvent is the final stage of SPE for obtaining a significant enrichment factor and high recovery of adsorbed metal ions on MWCNTs. Based on our survey of the literature, a newly synthesized Schiff base, 5-benzyl-4-[-chlororbenzylidene amine]-4H-1,2,4-triazole-3-thiol (BCBATT) was used as a chelating agent in combination with MWCNTs for the first time in this work as an effective sorbent for the separation and enrichment of trace quantities of Cd 2+ and Pb 2+ in various food and water samples. The effects of different experimental variables on both analyte ions’ recoveries were estimated quantitatively
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