Plumb job for polymer: Takes the lead

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  • Published: Apr 15, 2013
  • Author: David Bradley
  • Channels: Atomic
thumbnail image: Plumb job for polymer: Takes the lead

Chemical imprint

Lead-imprinted polymer particles. Credit: Food Chem/Elsevier/Behbahani et al

Researchers in Iran have used flame atomic absorption spectrometry (FAAS) to test a novel imprinted polymer designed to absorb contaminating lead ions from fresh fruit and vegetables for effective and inexpensive safety analysis and quality control.

Mohammad Behbahani, Akbar Bagheri, Mani Salarian, Laleh Adlnasab and Kobra Jalali of the Shahid Beheshti University, Evin, and colleagues Omid Sadeghi and Mohsen Taghizadeh of Islamic Azad University, Shahr-e-Rey Branch, in Tehran, have created polymeric particles imprinted with lead(II) ions. The synthesis, carried out in acetonitrile solvent using 2-vinylpyridine as a functional monomer, ethylene glycol dimethacrylate as the cross-linker, 2,2'-azobisisobutyronitrile as the initiator and diphenylcarbazone as the ligand. In a final step, the lead ions are released from the polymer particles using hydrochloric acid. Thus imprinted the particles can be used like a highly specific sponge for lead particles present in materials to which they are subsequently added.

Lead analysis

As we have discussed several times in the SpectroscopyNOW and SeparationsNOW ezines, lead is an insidious environmental and health hazard for millions of people across the globe who are exposed to polluted air, contaminated water and food grown on soils with higher than acceptable levels of this toxic metal. The main hazards associated with chronic exposure to small, but detrimental concentrations of lead, are damage to the organs, heart, intestine, kidneys, reproductive system, bone and to the nervous system, particularly the developing brains of children. Lead is also a proven carcinogen.

Along with cadmium, mercury, nickel and arsenic, exposure is a real and ongoing threat to the health and lives of many people. The World Health Organisation sets 10 micrograms per litre as an upper safe threshold for lead concentration in drinking water. There is thus a pressing need to develop efficient, effective and accessible technology for removing lead ions from water and for testing food products that may have been contaminated. The team reports that analytical work on lead usually involves FAAS, electrothermal atomic absorption spectrometry (ETAAS), graphite furnace atomic absorption spectrometry (GFAAS), inductively coupled plasma atomic emission spectrometry (ICP-AES), and inductively coupled plasma mass spectrometry (ICP-MS).

Simplification

These approaches are often costly, require sophisticated laboratory conditions and complex preparation of samples. The development of a lead-selective extractant could simplify considerably the preparation and resulting accuracy of tests based on atomic fluorescence spectrometry. The team has used suspect contaminated water samples, fish (bartail flathead), rice, vegetables and herbs (parsley, basil and mint) to demonstrate proof of principle.

The team carried out batch experiments to investigate sorption and desorption steps with their imprinted polymer. Extraction of lead(II) ions from spiked solutions and real samples was undertaken and FAAS used to determine lead content. The detection limit once processing was optimised was found to be 0.42 nanograms per millilitre of sample, the team reports with a standard deviation of 2.1 per cent. The team found that the same batch of imprinted polymer particles could be used again and again without loss of efficacy.

Related Links

Food Chem, 2013, 138, 2050-2056: "Synthesis and characterisation of nano structure lead(II) ion-imprinted polymer as a new sorbent for selective extraction and preconcentration of ultra trace amounts of lead ions from vegetables, rice, and fish samples"

Article by David Bradley

The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

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