New possibilities of matrix‐assisted laser desorption ionization time of flight mass spectrometry to analyze barley malt quality. Highly sensitive detection of mycotoxins

Abstract

The occurrence of mycotoxins in agricultural commodities is a major health concern for livestock, humans, and the environment. Barley and subsequently malt quality is of fundamental importance to obtain good quality beer. Classical methods of analysis often require tedious, laborious, and expensive processes. Matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) instrumentation enables highly sensitive and fast analysis and/or detection using a very small sample. The possibilities of MALDI-TOF MS for he identification and/or detection of trichothecene mycotoxins (deoxynivalenol (DON) and nivalenol (NIV), respectively) in barley malt were examined, and it was found that almost all classical MALDI matrices failed to ionize the compounds being studied. This detailed study of the ionization conditions and the search for unconventional matrices led to the discovery of suitable MALDI matrices, which enable ionization of trichothecene mycotoxins. These were: fine powdered synthetic diamond, sodium azide, or hydrazine hydrate. It is possible to detect 8.5 x 10(-12) mol (2.5 ng) of deoxynivalenol or 64 x 10(-12) mol (20 ng) of nivalenol in just 1 microL of barley malt extract (equivalent to 600 microg of DON in 1 kg of barley malt). The procedure developed enables fast determination of DON and NIV in barley, malt, or similar products.

Mass spectrometry of nanodiamonds

“…Diamond nanocrystals absorb UV light26 which suggests that they can be used as a matrix in matrix‐assisted laser desorption/ionization (MALDI) time‐of‐flight mass spectrometry (TOF MS). Common diamond powder has recently been described as a suitable matrix for the MALDI analysis of mycotoxins 27, 28. The use of NDs as a MALDI support for the detection of proteins has also been reported recently 29, 30…”

The defense response in Arabidopsis thaliana against Fusarium sporotrichioides

“…The type B trichothecenes, such as DON, were detected by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) [25]. Thus, we then established a method for quantification of T-2 toxin using MALDI-TOF MS. We tested sodium azide as a matrix for detecting T-2 toxin.…”

Mass spectrometry in multi-mycotoxin and fungal spore analysis

“…In a malt sample infected with Fusarium, but fieldtreated by fungicides, 393.5 ± 8.6 µg kg -1 DON was found, compared to 528.0 ± 84.0 µg kg -1 by HPLC analysis. Blechová et al (2006) conducted a similar study on DON and NIV, but did not achieve LOQs lower than 600 µg kg -1 for DON in barley malt. The first MALDI-TOF application for fumonisin B 1 was not a direct analysis of the mycotoxin itself, but the diazotization product of its deamination in contaminated feed, as identified by Lemke et al (2001).…”