Agriculture Reference
In-Depth Information
2.3.1.3 MALDI-MS in High-Throughput Analysis of Food
As can be seen in Table 2.3, MALDI-MS has been used to tackle various aspects of
food analysis, such as food authenticity control or analysis of natural components and
contaminants. Although most of the applications aim at qualitative analysis (screen-
ing, pro
fingerprinting), quantitation with MALDI is also possible with the
use of suitable internal standard [70,71]. In the following paragraphs, several
examples of the use of MALDI-MS for high-throughput food analysis are presented.
It is obvious that with work
ling, and
cant time reduction
can be achieved. Although sample pretreatment and MALDI matrix preparation
may be in some cases more time consuming compared with procedures involved
with conventional techniques, the increase in sample throughput is enabled by a
considerably lower analysis time (typically 1min versus tens of minutes in case of
HPLC
ows employing MALDI-MS, a signi
MS).
In a study by Catharino et al., MALDI-TOFMS was used to rapidly screen for
multiple a
-
atoxins in peanuts [73]. To minimize matrix-related ions, an ionic liquid
(triethylamine-
α
-cyano-4-hydroxycinnamic acid solution in methanol) was employed
as the MALDI matrix. In order to eliminate the formation of multiple ions of target
analytes, thus increasing the sensitivity of measurement, a 10 mM solution of NaCl
was added to the sample prior to analysis. As a result, only [M
Na]
+
adducts of
+
target a
atoxins were observed and LODs of 50 fmol were achieved. Only a single ion
was detected at
m
/
z
101, which was not interfering with signals of target a
atoxins. An
example of mass spectra obtained for both a standard and real peanut samples are
provided in Figure 2.4. The authors predicted that the proposed method would be
easily applicable to other mycotoxins and matrices.
Figure 2.4.
MALDI-TOF mass spectrum using triethylamine-
α
-cyano-4-hydroxycinnamic acid ionic
liquid as the matrix of (a) an equimolar mixture of aflatoxins B
1
,B
2
,G
1
, and G
2
(25 pg of each analyte);
(b) an equimolar mixture of a
atoxins B
1
,B
2
,G
1
, and G
2
(25 pg of each analyte spiked with 1
μ
l of a NaCl
solution (10mM); (c) aflatoxins detected as their Na
+
adducts from fungus-contaminated peanuts. Ref. [73],
Figure 2, p. 8156. Reproduced with permission of American Chemical Society.
