Concentrate hard: Improving FAAS

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  • Published: Jun 15, 2013
  • Author: David Bradley
  • Channels: Atomic
thumbnail image: Concentrate hard: Improving FAAS

Concentrating on heavy metal

Put your faith in FAAS for waterway environmental testing, preconcentrating heavy metals with nickel complex co-precipitate. Photo of Cottenham Lode and All Saints Church by David Bradley

A new preconcentration procedure for flame atomic absorption spectrometric (FAAS) determinations of heavy metals in food and water is both quick and simple to carry out. It exploits a nickel(II)/alpha-benzoin oxime precipitate to co-precipitate Cr(III), Cu(II), Fe(III), Pb(II), Pd(II) and Zn(II) ions from a sample.

Chemists Coşkun Özdemir, Şerife Saçmacı and Şenol Kartal at Erciyes University, in Kayseri, Turkey, explain that metals are an important component of toxic pollution as well as critical contaminants of food and water supply. Of course, natural processes such as erosion, volcanic activity, forest fires etc can lead to accumulation of soluble metals in the environment there are toxic effects measured at even low levels from anthropogenic sources.

Toxic and essential

They point out that even those metals considered essential to life, including zinc, copper and iron, are problematic at higher levels. By contrast cadmium, chromium and lead have no vital biological role and always represent a toxic issue above a certain threshold. The effects of toxic metals and toxic levels of essential metals are varied and disparate with health risks from asthma and allergy to cancer and neurological damage. It is important, therefore, to have straightforward and easy to carry out analytical tests for a wide range of metals for sample testing in environmental research and monitoring, food quality control and medical diagnostics.

Coprecipitation

Özdemir and colleagues have now turned to a co-precipitate compound, nickel(II)-alpha-benzoin oxime that allows them to improve the pre-concentration of various important metal ions prior to FAAS analysis. The co-precipitate dissolves in a small quantity of concentrated nitric acid without heating making it easy to handle in pre-preparation. The co-precipitation step takes less than thirty minutes. This, the team says, is the first time this compound has been used in this context and it shows what they describe as "good collecting ability" for this application with recovery of the target analyte metal ions being around 95% under optimised working conditions.

The team describes their approach as fast, precise and economic and of wide utility because it works not only with aqueous solutions but to food samples too. The detection limits they were able to achieve with this preconcentration method were superior to many other preconcentration/separation methods commonly employed in analytical laboratories. Moreover, their approach does not suffer from the interferences that plague conventional procedures.

Related Links

Analyt Methods 2013, online: Coprecipitation procedure for the determination of some metals in food and environmental samples by flame atomic absorption spectroscopy

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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