Determination of Cadmium, Zinc, Nickel and Cobalt in Tobacco by Reversed-Phase High-Performance Liquid Chromatography with 2-(8-Quinolylazo)-4,5-diphenylimidazole as a Chelating Reagent

Abstract

A sensitive and selective method has been developed for the simultaneous determination of cadmium, zinc, nickel and cobalt. The method is based on the chelation of metal ions with 2-(8-quinolylazo)-4,5-diphenylimidazole (QAI) and the subsequent reversed-phase (RP) high-performance liquid chromatographic separation and spectrophotometric detection of the metal chelates. The chelates were separated on an RP column with acetonitrile-water containing ethylenediamine tetraacetic acid and sodium acetate (pH 7.5). Though Zn(II) and Cd(II) chelates with azo compounds were generally labile in the RP column, these chelates with QAI were successfully detected. When analyses were carried out at 575 nm and at 0.001 absorbance unit full scale, the peak height calibration curves were linear up to 2.0 ng for Cd(II), 2.4 ng for Zn(II), 0.14 ng for Ni(II) and 0.72 ng for Co(II) in 100-µL injections, respectively; the detection limits (3σ, three times of the standard deviation for the blank signal) for Cd(II), Zn(II), Ni(II) and Co(II) were 4.8, 24, 2.4 and 7.2 pg in 100 µL of injected solution, respectively. The proposed method was successfully applied to the analysis of tobacco without any preliminary concentration or separation.

Liquid-Liquid Extraction and Liquid Chromatographic Studies on Interactions of Inorganic Anions with Coordinatively Unsaturated Copper(II) Complexes of Heterocyclic Azo Compounds

“…Although a related reagent of 2-(8-quinolylazo)-4,5-diphenylimidazole was studied as a precolumn derivatizing reagent for the separation of Cd, Zn, Ni, and Co at pH 7.5, the copper complex was not detected as a peak. 13 The stable species at such pH was CuR2 2+ , which gradually dissociated after separation from an excess ligand. The retention of a free ligand was also slightly enhanced in the presence of SCN -, due to more favorable distribution of the cationic species (HR + , pKa 4.1).…”

Mineral Contents of Selected Medicinal and Stimulating Plants in Ethiopia

“…The levels of essential and non-essential metals in linseed samples collected from five different sites (Bale, East Gojam, Shoa, South Wello and Tigray) in Ethiopia were determined by flame atomic absorption spectrometry. The levels (mg kg -1 ) of metals determined were in the ranges Na (242-614), K (6,494-6,755), Mg (2,679-3,118), Ca (540-744), Cr (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30), Mn (17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28), , Co (23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42), Ni (12-...…”

“…It is highly toxic and gets accumulated by tobacco plants. Most heavy metals cause a significantly serious damage on human health [31]. One of the main sources of toxic metals in our environment is tobacco smoke.…”

Determination of cobalt, nickel and iron at trace level in natural water samples by in-column chelation-reversed phase high-performance liquid chromatography

“…On the other hand, high-performance liquid chromatography (HPLC) is a promising technique for multielement determination of ultratrace metal ions as metal chelates, providing advantages in sensitivity, robustness, and cost-effectiveness (Takahashi et al 2008;Yang et al 2005Yang et al , 2004Zhang et al 2005;Yasui et al 2008;). HPLC with a convenient detector meets most of the analytical requirements of simultaneous metal determination such as separation, identification, and quantification of different species down to trace levels.…”