Analytical methods and recent developments in the detection of melamine

https://doi.org/10.1016/j.trac.2010.06.011Get rights and content

Abstract

Melamine (MEL) is an emerging contaminant in milk, infant formula and pet food, and is the subject of much recent research. This review focuses on analytical methods for detecting MEL residue.

We present and discuss the advantages, the disadvantages and the applicability of methods, including common techniques [e.g., capillary electrophoresis, high-performance liquid chromatography (HPLC), LC with mass spectrometry (LC-MS), LC with tandem (LC-MS2), gas chromatography with MS (GC-MS), matrix-assisted laser desorption/ionization MS (MALDI-MS), nuclear magnetic resonance spectroscopy, vibrational spectroscopy, chemiluminescence analysis and immunoassay] and several novel detection methods.

We propose that the new generation of analytical methods for detecting MEL requires development of powerful analytical devices, combination of multiple techniques, and application of new materials.

Introduction

The detection of melamine (2, 4, 6-triamino-s-triazin, MEL) in food products has been the subject of much recent research. MEL is a synthetic compound, commonly used as an industrial chemical in the production of MEL-formaldehyde polymer resins for laminates, coatings, commercial filters, glues or adhesives, and plastics and flame-retardants [1]. Because it contains 66% nitrogen, MEL was added to cattle feed as a non-protein nitrogen (NPN) source in 1958, but its use was discontinued in 1978, because it is incompletely hydrolyzed in ruminants [2].

However, because the Kjeldahl method that measures total nitrogen content as an indication of protein levels is non-scientific, unethical manufacturers deliberately added MEL to food and food-related products (e.g., milk, infant formula, frozen yogurt, biscuits, candy, coffee drinks, and pet food) to boost the nitrogen level and to reduce costs [3], [4]. Although MEL has low toxicity, it may lead to kidney stones, eventual renal failure, and ultimately death, when it forms an insoluble compound (see Fig. 1) with the analog cyanuric acid (CYA) [5], [6], [7]. Pathogenesis may be through formation of high-molecular-weight network complexes by self-association of MEL-CYA, which has poor aqueous solubility and precipitates in renal tubules, causing urinary system damage and ultimately death [8], [9].

In 2004, an outbreak of food adulteration with MEL led to renal failure in dogs and cats in Asia [10]. In the spring of 2007, pet food adulterated with MEL was blamed for the illness or death of thousands of dogs and cats in the USA [11].

In September 2008, the occurrence of kidney stones in thousands of infants across China captured the attention of the world. According to a report from the Ministry of Health (MOH), in the People’s Republic of China, more than 54,000 infants and young children were hospitalized, and at least six children died in this incident [4], [12]. An investigation revealed that the illnesses resulted directly from consumption of milk, infant formula, or related dairy products adulterated with MEL, so rapid, widely available, cost-effective methods for detecting MEL in various substances are of paramount importance.

In this review, we present an overview of the advanced analytical methods for measuring MEL and analog contaminants in various foods. We try to be comprehensive and highlight new developments, and discuss theoretical and technical aspects of methods for MEL-contaminant screening and confirmation. We also preview trends and new detection methods based on new materials.

Section snippets

Sample preparation

Food samples are typically complex matrices that are difficult to analyze because of the abundance of proteins and carbohydrates. Effective isolation and extraction of MEL and analogs from complex matrices is necessary prior to MEL determination. The main objectives of sample treatment, including extraction, preconcentration, and derivatization, are to achieve lower limits of detection (LODs) by removing matrix constituents that may affect detection or enrichment of analytes [13]. However,

Background contamination and analysis of melamine

In 2007, MEL was found in pet-food products, and led to kidney toxicity in dogs and cats in the USA. Later, MEL contamination was found in milk-based products in China. Because China is a major exporter of milk products and ingredients, the events created a widespread food-safety scare. Reports of MEL-contaminated foods manufactured in the USA and other countries occurred in subsequent months [26].

These MEL-contamination incidents prompted the US Food and Drug Administration (FDA), the European

Modern instrument analytical methods

To date, CE, HPLC, LC-MS, LC-MS2, GC-MS, MALDI-MS, NMR spectroscopy and vibrational spectroscopy techniques have been the most important published methods.

Immunoassay

Immunoassays and related immunochemical analytical procedures [e.g., ELISA, immunochromatographic assay (ICA), and fluorescence polarization immunoassay (FPIA)] have been widely used to detect various residues in foods and environment. However, ICA and FPIA have not been reported so far for MEL.

The use of ELISA for the determination of MEL has been reported in only a few papers. A comparison was made between three commercial ELISA test kits [i.e. Abraxis Melamine Plate kit (5005B), Abraxis

Novel detection methods

Recently, sensor technology has been widely used for the detection of residues in foods because of its sensitivity, rapidity, simplicity and cost effectiveness. Sensors have also been developed for the analysis of MEL and its analogs including MIP-based and NP-based sensors.

Conclusion and trends

The recent reports summarized in this review show that many methods have been developed for detecting MEL residues in various matrices. The different methods each have their advantages, disadvantages, and requirements for sample preprocessing of complex samples.

HPLC will continue to be widely used for MEL detection, and it will certainly be combined with other techniques.

GC-MS is an important and ideal method for detecting trace samples. GC-MS generally purifies and resolves samples, and

References (80)

  • E.Y. Chan et al.

    Lancet

    (2008)
  • H.H. Yang et al.

    Talanta

    (2009)
  • J.G. Xia et al.

    Food Control

    (2010)
  • J.P. Toth et al.

    J. Chromatogr.

    (1987)
  • H. Miao et al.

    Biomed. Environ. Sci.

    (2009)
  • J. Li et al.

    J. Chromatogr., A

    (2009)
  • E.A.E. Garber

    J. Food Prot.

    (2008)
  • Z.Y. Wang et al.

    Anal. Chim. Acta

    (2010)
  • W. Chen et al.

    Biosens. Bioelectron.

    (2009)
  • L. Li et al.

    Food Chem.

    (2010)
  • C.F. Peng et al.

    Biosens. Bioelectron.

    (2009)
  • W. Ma et al.

    Biosens. Bioelectron.

    (2009)
  • H.L. Xie et al.

    Anal. Chim. Acta

    (2009)
  • World Health Organization, 1–4 December 2008, Executive Summary (Accessed at:...
  • G.L. Newton et al.

    J. Anim. Sci.

    (1978)
  • World Health Organization, September-October 2008 (Accessed at:...
  • Oxford University Press, Sci. Daily [online], 16 October 2008 (Accessed at:...
  • Michigan State University, Sci. Daily [online], 13 December 2007 (Accessed at:...
  • University of Guelph, Sci. Daily [online], 3 May 2007 (Accessed at:...
  • R.L.M. Dobson et al.

    Toxicol. Sci.

    (2008)
  • C.T. Seto et al.

    J. Am. Chem. Soc.

    (1990)
  • C.A. Brown et al.

    J. Vet. Diagn. Invest.

    (2007)
  • US Food and Drug Administration, 2007 (Accessed at:...
  • Ministry of Public Health of China, 23 January 2009 (Accessed at:...
  • Y. Yuan et al.

    Crit. Rev. Anal. Chem.

    (2008)
  • W.C. Andersen, S.B. Turnipseeed, C.M. Karbiwnyk, M.R. Madson, 2008 (Accessed at:...
  • S. Michael, A.J. Krynitsky, 1 June 2010 (Accessed at:...
  • E. Esteban, 1 December 2006 (Accessed at:...
  • M.S. Filigenzi et al.

    J. Agric. Food Chem.

    (2008)
  • S. Turnipseed, C. Casey, C. Nochetto, D.N. Heller, 2007 (Accessed at:...
  • Standardization Administration, People’s Republic of China, 7 October 2008 (Accessed at:...
  • X.L. Zhu et al.

    J. Agric. Food Chem.

    (2009)
  • S.A. Tittlemier et al.

    J. Agric. Food Chem.

    (2009)
  • R.A. Yokley et al.

    J. Agric. Food Chem.

    (2000)
  • W.H. Zhou et al.

    Fenxi Ceshi Xuebao

    (2009)
  • L. He, Y. Su,Y. Zheng, X. Huang, L. W, Y. Liu, Z. Zeng, Z. Chen, J. Chromatogr., A 1216 (2009)...
  • J.R. Ingelfinger

    New Engl. J. Med.

    (2008)
  • Ž. Černova et al.

    Chemija

    (2009)
  • Z.J. Chen et al.

    J. Agric. Food Chem.

    (2009)
  • N. Yan et al.

    J. Agric. Food Chem.

    (2009)
  • Cited by (182)

    • Aptamer-based analysis of food contact material migrants

      2023, Aptamers for Food Applications: Safety, Authenticity, and Integrity
    • Co-exposure of melamine and cyanuric acid as a risk factor for oxidative stress and energy metabolism: Adverse effects on hippocampal neuronal and synaptic function induced by excessive ROS production

      2022, Ecotoxicology and Environmental Safety
      Citation Excerpt :

      Melamine (MEL, 2,4,6-triamino-1,3,5-triazine), a synthetically produced chemical, is widely used for the manufacture of plastics, laminates, glues, fertilizers, kitchenware, adhesives and other products (Sun et al., 2010).

    View all citing articles on Scopus
    View full text