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New sensitive method for chromium speciation analysis: No hexavalent chromium in dairy and cereal products

(24.08.2016)


Background:
Chromium is released to the environment mainly as a result of its widespread industrial use. Chromium exists in a variety of oxidation states, the trivalent (Cr(III)) and hexavalent (Cr(VI)) states being relatively stable and largely predominant. These two states differ markedly with respect to chromium bioavailability, absorption, mode of action and toxicity.

Since hexavalent chromium is classified as genotoxic and carcinogenic, its presence in food cannot be tolerated. However, since Cr(VI) is a strong oxidant, it is well accepted that due to the presence of organic matter, foodstuffs of plant and animal origin cannot contain significant amounts of Cr(VI). Despite such general agreement, several researchers have reported the presence of Cr(VI) in biological materials including food such as tea and bread (see the EVISA News below).

However, the results of these studies have recently been the object of controversy. Indeed, a group of researchers from the Jozef Stefan Institute in Ljubljana (Slovenia) found that former studies indicating the presence of hexavalent chromium in foodstuffs such as tea or bread based solely on the alkaline extraction of chromium are biased. Using a highly selective approach of the hyphenated technique of LC-ICP-MS for chromium speciation analysis they proved that the reported hexavalent chromium is just an artifact of a technique not sufficiently selective to differentiate between trivalent and hexavalent chromium (see the EVISA news below). More recently, using an on-line speciation technique by ion chromatography–inductively coupled plasma mass spectrometry (IC–ICPMS), a group of French and Spanish researchers could not find Cr(VI) in any of the samples investigated. However, their method lacked sensitivity (LOQ of 3 µg/L in dairy products and 30 µg/kg in other foodstuffs).

The new study:

A group of French researchers now optimised their methodology for chromium speciation analysis of food samples with respect to extraction efficiency and detection power. The method was optimised by using an experimental design and validated for the determination of Cr(VI) in different food materials such as dairy products and cereal products. The method developed was free from interferences possibly associated with chloride and organic or inorganic carbon and proved satisfactory with respect to linearity, specificity, sensitivity, accuracy, repeatability and intermediate precision. Using on-line hyphenation between  high-performance ionic chromatography with inductively coupled plasma mass spectrometry limits of quantification could be significantly improved compared to former approaches and ranged from 0.6 µg/kg in dairy products to 0.8 µg/kg in cereal products. Despite the method’s very high sensitivity, Cr(VI) was not found in any of the studied samples including those of high chromium content. The authors believe that their results confirm the results of the most recent studies using an on-line speciation method, and invalidates older studies that found traces of Cr(VI) in food by using a less specific off-line speciation method.

The original study:

Fanny Hernandez, Fabienne Séby, Sandrine Millour, Laurent Noël, Thierry Guérin, Optimisation of selective alkaline extraction for Cr(VI) determination in dairy and cereal products by HPIC–ICPMS using an experimental design, Food Chem., 214 (2017) 339–346. doi: 10.1016/j.foodchem.2016.07.099


Used Instrumentation and materials:


HPLC-ICP-MS
Thermo Scientific: HPIC pump: ICS 5000
Thermo Scioentific: ICP-MS: iCAP Q
Anton Paar: Microwave digestion system: Multiwave 3000
Agilent Technologies: ICP-MS: 7700 x

Certified reference material ERM-CE278k (mussel tissue)


Related Studies (newest first):

Véronique Vacchina,  Inmaculada de la Calle, Fabienne Séby, Cr(VI) speciation in foods by HPLC-ICP-MS: investigation of Cr(VI)/food interactions by size exclusion and Cr(VI) determination and stability by ion-exchange on-line separations, Anal. Bioanal. Chem., 407 (2015) 3831–3839. doi: 10.1007/s00216-015-8616-3

B. Novotnik, T. Zuliani, J. Scancar, R. Milacic, Content of trace elements and chromium speciation in Neem powder and tea infusions. J. Trace Elem. Med. Biol., 31 (2015) 98–106. doi: 10.1016/j.jtemb.2015.04.003

Shizhong Chen, Shengping Zhu, Yuanyuan He, Dengbo Lu, Speciation of chromium and its distribution in tea leaves and tea infusion using titanium dioxide nanotubes packed microcolumn coupled with inductively coupled plasma mass spectrometry, Food Chem., 150 (2014) 254–259. doi: 10.1016/j.foodchem.2013.10.150

Breda Novotnik, Tea Zuliani, Janez Scancar, Radmila Milačič, Chromate in food samples: an artefact of wrongly applied analytical methodology?, J. Anal. At. Spectrom., 28 (2013) 558-566. DOI: 10.1039/c3ja30233d

Shahryar Abbasi, Atousa Bahiraei, Ultra trace quantification of chromium(VI) in food and water samples by highly sensitive catalytic adsorptive stripping voltammetry with rubeanic acid, Food Chem., 133 (2012) 1075–1080. doi: 10.1016/j.foodchem.2012.02.003

Khakhathi L. Mandiwana, Nikolay Panichev, Svetlana Panicheva, Determination of chromium(VI) in black, green and herbal teas, Food Chem., 129 (2011) 1839–1843. doi: 10.1016/j.foodchem.2011.05.124

M.E. Soares, E. Vieira, M.L. Bastos, Chromium speciation analysis in bread samples, J. Agric. Food Chem., 58 (2010) 1366–1370. doi: 10.1021/jf903118v

Abayneh A. Ambushe, Robert I. McCrindle, Cheryl M. E. McCrindle, Speciation of chromium in cow's milk by solid-phase extraction/dynamic reaction cell inductively coupled plasma mass spectrometry (DRC-ICP-MS), J. Anal. At. Spectrom., 24/4 (2009) 502-507.
DOI: 10.1039/b819962k

Maria Elisa Soares, Elsa Vieira, Maria de Lourdes Bastos, Chromium Speciation Analysis in Bread Samples, J. Agri. Food Chem., 2009. DOI: 10.1021/jf903118v

Róbert Kovócs, Aron Béni, Roland Karosi, Csilla Sógor, József Posta, Investigation of chromium content in foodstuffs and nutrition supplements by GFAAS and determination of changing Cr(III) to Cr(VI) during baking and toasting bread, Food Chem., 105 (2007) 1209–1213. doi: 10.1016/j.foodchem.2007.02.030

Estela Figueiredo, M. Elisa Soares, Paula Baptista, Marisa Castro, M. Lourdes Bastos, Validation of an Electrothermal Atomization Atomic Absorption Spectrometry Method for Quantification of Total Chromium and Chromium(VI) in Wild Mushrooms and Underlying Soils, J. Agric. Food Chem. 2007, 55, 7192-7198. doi: 10.1021/jf0710027

N. Panichev, T, K. Mandiwana, M. Kataeva, S. Siebert, Determination of Cr(VI) in plants by electrothermal atomic absorption spectrometry after leaching with sodium carbonate, Spectrochim. Acta B, 60 (2005) 699– 703. doi: 10.1016/j.sab.2005.02.018

Maria E. Soares, Maria L. Bastos, Margarida Ferreira, Selective Determination of Chromium (VI) in Powdered Milk Infant Formulas by Electrothermal Atomization Atomic Absorption Spectrometry after Ion Exchange, J. AOAC International, 83/1 (2000) 220-223.

J. Lameiras, M.E. Soares, M.L. Bastos, M. Ferreira, Quantification of total chromium and hexavalent chromium in UHT milk by ETAAS, Analyst (London), 123/10 (1998) 2091-2095. DOI: 10.1039/a804700f



 Related EVISA Resources

Link Database: Chromium as an essential nutrient
Link Database: ATSDR: Toxicological Profile for Chromium
Link Database: More about Cr(III)/Cr(VI)
 Link Database: Toxicity of hexavalent chromium (chromate)
 Link Database: Methods for chromium speciation analysis
Link Database: All about hexavalent chromium
Link Database: Legislation related to chromium
Brief summary: ICP-MS: A versatile detection system for trace element and speciation analysis
Brief summary: LC-ICP-MS - The most often used hyphenated system for speciation analysis
Brief summary: Standard methods for chromium speciation analysis
Material Database: Certified reference materials for Cr(VI)



 Related EVISA News

April 26, 2015: Hexavalent chromium in food ?
March 12, 2013: Chromate in food samples: an artefact of wrongly applied analytical methodology
November 15, 2009: Hexavalent chromium found in bread
May 17, 2007: Hexavalent Chromium in Drinking Water Causes Cancer in Lab Animals


last time modified: August 24, 2016



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