The future of mycotoxin analysis

							Techniques            We investigate the tools behind the data or new applications for common methods




                              The future of mycotoxin analysis
                              IN MYCOTOXIN ANALYSIS, WELL ESTABLISHED METHODS BASED ON CHROMATOGRAPHIC PRINCIPLES ARE HOLDING

                              THEIR GROUND, BUT A TRANSITION TO MULTITOXIN AND RAPID METHODS CAN BE OBSERVED. ALSO, A NUMBER OF

                              NEW TECHNIQUES SUCH AS BIOSENSORS ARE RAPIDLY EMERGING SAY RUDOLF KRSKA AND ELVIRA WELZIG.




                              F
                                    or close surveillance of mycotoxins in the food                 European Mycotoxin Awareness Network (EMAN,
                                    chain, analytical methods have been developed                   www.mycotoxins.org). Overestimation can sometime be a
                                    and refined since the 1960s1. Because mycotoxins                drawback, and ELISA’s may be influenced by matrix
                              are compounds of different chemical structure and                     composition. In the past several years, test kits based on
                              physicochemical properties, specific detection methods                the mostly indirect competitive principle for field use
                              have evolved using well established techniques on the                 have emerged. First, dipsticks were developed, but the
                              basis of liquid (LC) or gas chromatography (GC) with                  consecutive dipping of the small strip into several solu-
                              appropriate detectors such as fluorescence detection                  tions was soon found impractical and they were
                              (FLD), UV detection, flame ionisation detection (FID),                replaced by lateral flow devices (LFD). These are also
                              electron capture detection (ECD) and mass spectrometry                often, wrongly, named dipsticks, but they are based on
                              (MS). Although the methods are usually optimised for                  competitive test principles using stained antibodies with
                              one target mycotoxin, or at best a group of closely                   either latex particles or colloidal gold as the label. LFDs
                              related mycotoxins as for instance the B-trichothecenes,              are available for aflatoxins and deoxynivalenol (DON).
                              multimycotoxin methods are highly desired. Because LC
                              with tandem mass spectrometry (LC-MS/MS) has been                     EMERGING TECHNIQUES
                              progressing strongly, the simultaneous determination of               In order to further cut down costs and time, new ana-
                              up to 40 different mycotoxins is now feasible2.                       lytical techniques are enthusiastically incorporated into
                              Sophisticated LC-MS/MS equipment does not require                     mycotoxin analysis. However, it is often a long way
                              sample clean-up especially when isotope labelled inter-               from the bench to commercially available products.
                              nal standards are used. However, the conditions during                Biosensors such as fluorescence polarisation immunoas-
                              sample preparation and chromatographic separation are                 say (FPI) and surface plasmon resonance (SPR) have
                              often a compromise, and even LC-MS/MS is not com-                     reached this point. Some of the most interesting emerg-
Prof Dr Rudolf Krska is       pletely devoid of matrix interferences in the form of                 ing techniques for the detection of mycotoxins in
the head of the Center
                              signal suppression. In spite of its immense potential, it             grains are non-invasive methods such as Fourier
for Analytical Chemistry
at the IFA-Tulln, Austria.    will take some time for LC-MS/MS to be implemented in                 Transform mid-infrared spectroscopy with attenuated
After his degree in chem-     routine analysis because of the high investment costs.                total reflection (ATR) or near infrared transmission
istry at the Vienna           Apart from new chromatographic columns that are fre-                  spectroscopy, reducing sample preparation to an
University of Technology,
                              quently introduced to mycotoxin analysis, clean-up has                absolute minimum. However, major restrictions of spec-
he started his postdoc-
toral studies in the field    undergone considerable development. Nowadays,                         troscopic techniques include high matrix dependence
of mycotoxin analysis at      immunoaffinity columns, SPE material in disposable                    and lack of appropriate calibration material. This
Health Canada in Ottawa.      plastic cartridges and MycoSep® columns are available                 already alludes to the topic of quality assurance in lab-
Krska has been coordina-
                              commercially for all major mycotoxins.                                oratories dealing with mycotoxin analysis. Several
tor of several European
Commission funded proj-                                                                             measures are now available including the regular par-
ects dealing with the cer-    ELISA AND DIPSTICKS                                                   ticipation in proficiency testing organised by, for
tification of reference       A number of rapid methods, based on immunochemical                    example, FAPAS (www.fapas.com) and, although not
materials for the myco-
                              techniques, mostly do not require any clean-up or ana-                complete by far, a good range of (certified) reference
toxins, with more than 35
participating laboratories    lyte enrichment. Enzyme linked immunosorbent assays                   materials (C)RM. Both matrix RM and calibrant CRM
since 1998. Since 2002        (ELISA) have become one of he most useful tools for the               are offered especially for aflatoxins and Fusarium tox-
he has also been head of      rapid monitoring of mycotoxins, especially for the                    ins. A complete list of available CRMs is available from
the Christian Doppler
                              screening of raw materials. The great advantages of                   COMAR (www.comar.bam.de) enabling traceability and
Laboratory for Mycotoxin
Research in Tulln.            micro-plate (MTP)-ELISAs are speed, sensitivity, speci-               comparability of analytical results in mycotoxin analy-
                              ficity, easy operation, and high sample throughput                    sis. <-
                              achieved by full automation by means of robots. A list
                              of commercial immunological test kits (and specifica-                 References 1-2 are available on request.
                              tions) for the analysis of mycotoxins is compiled by the              Photo: USDA



                                                  FEED ● MIX vol.14 no.1 2006   W W W. AG R I WO R L D . N L   -9