The preparation, validation and certification of the aflatoxin content of two peanut butter reference materials

Opinion: Multi-Mycotoxin Reference Materials

The analysis of mycotoxins in food and feed using liquid chromatography coupled with mass spectrometry is considered advantageous because the hyphenated technology enables simultaneous determination of multiple mycotoxins. Multi-mycotoxin analysis requires special consideration of quality control parameters to ensure proper evaluation of data quality for all target mycotoxins in method development and routine sample analysis. Mycotoxin matrix reference materials, especially certified reference materials, are stable and homogeneous matrices with certified traceability, concentrations, and uncertainty for mycotoxin(s) of interest. The use of these reference materials for single mycotoxin analysis has been a well-accepted practice and should be extended to multi-mycotoxin analysis. This opinion piece discusses the following essential metrological and operational components to improve data quality: (1) purposes of multi-mycotoxin reference materials; (2) comparison of reference materials, certified reference materials, and in-house quality control materials; (3) advantages of using reference materials for multi-mycotoxin analysis; (4) current trends and challenges of multi-mycotoxin reference materials. Potential applications of reference materials discussed here can improve routine mycotoxin determination and will lead to better accuracy and consistency of results. Quality control processes that incorporate reference materials in the field of mycotoxin analysis ensure successful development and implementation of liquid chromatography mass spectrometry-based multi-mycotoxin methods.

Overview of mycotoxin methods, present status and future needs

This article reviews current requirements for the analysis for mycotoxins in foods and identifies legislative as well as other factors that are driving development and validation of new methods. New regulatory limits for mycotoxins and analytical quality assurance requirements for laboratories to only use validated methods are seen as major factors driving developments. Three major classes of methods are identified which serve different purposes and can be categorized as screening, official and research. In each case the present status and future needs are assessed. In addition to an overview of trends in analytical methods, some other areas of analytical quality assurance such as participation in proficiency testing and reference materials are identified.

Application of the assay of aflatoxins by liquid chromatography with fluorescence detection in food analysis

HPLC using fluorescence detection has already become the most accepted method for the determination of aflatoxins due to its several advantages over other analytical methods. Both normal- and reversed-phase HPLC can be used. However the reversed-phase HPLC methods are more popular. Liquid chromatographic determination of aflatoxins using fluorescence detection and its application in food analysis is reviewed in this article.

Analysis of mycotoxins in food and feed: certification of DON in wheat and maize

Worldwide there are either statutory limits or in some instances advisory guidelines for the maximum levels of mycotoxins in foods and feeds. These limits which have been agreed for the protection of human health and as standards for trade are often set at surprisingly low levels in view of both the problems of sampling and the abundant evidence of the difficulties of mycotoxin analysis, particularly so when approaching the limits of detection. Improved methodology for mycotoxins and improvements in performance even of expert laboratories have, however, been achieved through intercomparison exercises organised by the EC Measurement and Testing programme (formerly BCR). On a wider scale, participation in proficiency testing through schemes such as the UK Food Analysis Performance Assessment Scheme (FAPAS) have indicated that between 10 and 40% of laboratories experience difficulties in obtaining satisfactory results in monitoring mycotoxins. Reference materials provide an important means of checking method performance. BCR has made a unique contribution in the production and certification of maize and wheat reference materials naturally contaminated with the Fusarium mycotoxin 4-deoxynivalenol (DON), which has now been available for purchase for some 2 years.

The development of five animal feed reference materials, certified for their aflatoxin B1 content

The development of three peanut meal and two compound feed reference materials and the certification of their aflatoxin B1 content is described. The materials were prepared and certified within the Measurements and Testing Programme of the Commission of the European Communities as part of a broad activity to improve accuracy and agreement of results of measurements on food and agriculture. RM 262 (peanut meal) was prepared from uncontaminated peanut products. RM 263 and RM 264 (peanut meals) were prepared from naturally contaminated peanuts which were blended with uncontaminated ones, to achieve the desired aflatoxin B1 mass fractions. RM 375 and RM 376 (compound feeds) were made by blending decontaminated dairy feed together with commercial feed ration and contaminated dairy feed with several feed compounds, respectively. Details are given of the preparation and the investigations to verify homogeneity and stability of the materials. The certification exercise was carried out by 17 laboratories using a variety of extraction and clean-up procedures. Most laboratories used liquid chromatography as the determinative step, although operating under a variety of chromatographic conditions. A few laboratories applied thin layer chromatography with densitometric quantification. Peanut meal RM 262 was certified as containing aflatoxin B1 at a mass fraction of < 3 micrograms/kg, RM 263 at 43.3 +/- 2.1 micrograms/kg and RM 264 at 204 +/- 10 micrograms/kg. Compound feed RM 375 was certified as containing aflatoxin B1 at a mass fraction of < 1 micrograms/kg and RM 376 at 9.2 +/- 0.5 micrograms/kg. The materials can be employed either to establish or confirm a calibration curve, or to check the performance of a method.

Recent advances in analytical methods for mycotoxins

Recent advances in analytical methods are reviewed using the examples of aflatoxins and trichothecene mycotoxins. The most dramatic advances are seen as being those based on immunological principles utilized for aflatoxins to produce simple screening methods and for rapid specific clean-up. The possibilities of automation using immunoaffinity columns is described. In contrast for the trichothecenes immunological methods have not had the same general impact. Post-column derivatization using bromine or iodine to enhance fluorescence for HPLC detection of aflatoxins has become widely employed and there are similar possibilities for improved HPLC detection for trichothecenes using electrochemical or trichothecene-specific post-column reactions. There have been improvements in the use of more rapid and specific clean-up methods for trichothecenes, whilst HPLC and GC remain equally favoured for the end-determination. More sophisticated instrumental techniques such as mass spectrometry (LC/MS, MS/MS) and supercritical fluid chromatography (SFC/MS) have been demonstrated to have potential for application to mycotoxin analysis, but have not as yet made much general impact.