Agriculture Reference
In-Depth Information
and ADONs in SPE-puri
water extracts of barley and malt. The use of
sodium azide matrix provided good reproducibility and relatively low limits of
detection ranging from 0.6 to 0.9
ed acetonitrile
-
g/ml. The authors also explored the capability
of the method to quantify DON in naturally contaminated malt based on external
calibration. The results for DON obtained by MALDI
μ
-
TOFMS and the reference
HPLC
g/kg, respectively.
Work published by Catharino et al. [68] described the MALDI
-
MS/MS method were 507
±
9 and 780
±
124
μ
-
TOFMS protocol
for screening a
atoxins (AFB1, AFB2, AFG1, and AFG2) in peanuts at concentra-
tions as low as 50 fmol. The use of an ionic liquid matrix (triethylamine
-cyano-4-
hydroxycinnamic acid solution in methanol) enabled the acquisition of interference-
free mass spectra. The target mycotoxins were isolated from the samples by a
procedure based on extraction with an aqueous
-
α
-
methanol solution containing potas-
sium chloride and chloroform and puri
ed with the use of CuSO
4
and diatomaceous
earth (Celite).
An interesting MALDI
TOFMS approach to qualitative analysis of gliotoxin was
reported by Davis et al. [69], who developed a single-pot derivatization strategy using
sodium borohydride-mediated reduction of gliotoxin followed by immediate alkyla-
tion of exposed thiols by reaction with 5
´
-iodoacetamido
-
uorescein to yield a stable
H]
+
product, diacetamido
uorescein-gliotoxin, of molecular mass 1103.931 Da ([M
+
ion). Unlike free gliotoxin, this product was readily detectable by MALDI
TOFMS at
concentrations above 530 fmol. Although demonstrated only for the analysis of
Aspergillus fumigatus
culture supernatants, the above strategy may also be applicable
to analysis of extracts of food and feed.
Marchetti-Deschmann et al. [70] used MALDI
-
TOFMS to classify closely related
Fusarium
species responsible for
Fusarium
head blight disease of crops based on the
analysis of intact spores. The spore suspensions were directly embedded into a
MALDI matrix without laborious sample cleanup or enrichment steps and the surface-
associated compounds were analyzed by MALDI
-
TOFMS. These mass spectra were
used to develop partial least-squares discriminant analysis (PLSDA) models for
sample classi
-
cation. The authors demonstrated the potential to build a database for
accurate
Fusarium
species identi
cation and for fast response in the case of infection
in the corn
TOFMS was used to identify resistance-
associated proteins in response to
Aspergillus
eld. In another study, MALDI
-
avus
infection under drought
stress [71]. MALDI
cation of
conjugates of mycotoxins with proteins, which can also be used in analytical
applications, such as immunogens for production of selective antibodies [72,73]
or as biomarkers of intoxications with mycotoxins [74].
-
MS is also frequently used for detection and identi
8.4.2 Ambient Ionization Mass Spectrometry
Novel ambient desorption ionization techniques such as direct analysis in real time
(DART) and desorption electrospray ionization (DESI) hold great potential in high-
throughput analysis of food. Various techniques and principles have been described in
other chapters. Only a few applications were described for the analysis of mycotoxins
in food and feed with the use of ambient ionization MS.
