Agriculture Reference
In-Depth Information
Madla et al. investigated the use of MALDI-MS for determination of pesti-
cides [76]. The technique enabled the detection of 12 of 15 tested compounds below
their maximum residue limits (MRLs) and good linearity was observed for responses
of analytes in the concentration range of 0.001
50mg/kg. However, different
matrices (either CHCA or DHB) had to be used to achieve acceptable sensitivity
and the method was not evaluated for real food matrices.
A promising approach to discrimination of
-
fish species differing by commercial
value was reported by Mazzeo et al. [74]. Following a simple and rapid sample
extraction procedure with 0.1% aqueous formic acid (the overall time requirements
for sample preparation were below 15min per sample), highly speci
c MALDI mass
spectrometric pro
les containing biomarkers identi
ed as parvalbumins (
(fish muscle
proteins) were obtained from 25
fish species. Interestingly, the biomarkers exhibited a
remarkable stability, as the heat-treated sample extracts provided mass spectra
identical to those obtained for untreated samples. These results indicate that the
method might be applicable to the authenticity control of cooked
fish products as well
as to raw
fish-based commercial foods.
Calvano et al. used MALDI-TOFMS as a tool for the detection of adulteration of
extra virgin olive oil (EVOO) with hazelnut oil based on the pro
le of phospholipids
(PLs) [77]. Hazelnut oil is frequently used to adulterate olive oil due to its chemical
similarity to olive oil in terms of triacylglycerols, sterols, and fatty acids composition.
The authors developed a rapid and selective extraction procedure using an ionic liquid
(arising from tributylamine and
-cyano-4-hydroxycinnamic acid) to isolate the PL
fraction from subject oil. An identical ionic liquid was also used as the MALDI matrix.
Such an experimental setup enabled a signi
α
cant increase of PL signal and elimination
of ions formed from other oil components. With regard to distinct differences between
PL concentrations in olive oil (30
-
60
μ
g/kg) and hazelnut oil (10
-
20 g/kg), detection of
adulteration levels as low as 1% was possible.
Garcia et al. developed a MALDI-based robust method for high-throughput forensic
screening of milk powder adulteration by cheap vegetable oils and fats based on the
pro
le of triacylglycerols [78]. With regard to simple sample preparation (sample
shaken with
n
-hexane for 1min followed by centrifugation for 2min) and direct
examination without prior chromatographic separation, the proposed method showed
signi
cant time-saving advantages compared with traditional methods using GC or LC
(overall procedure time below10min per sample). Additionally, themethod also has the
potential for identi
cation of the type of material used for adulteration.
2.3.2 Headspace (Solid-Phase Microextraction)-Mass Spectrometry E-Nose
The electronic nose based on themass detector referred to asHS-MS andHS-SPME-MS
e-nose (also referred to as a chemical sensor) is able to carry out analyses in very short
times and with minimum sample preparation. In this instrumental setup, the volatile
compounds are extracted from the headspace above the sample. Headspace methods
include static headspace, dynamic headspace (purge and trap), and SPME [84].
SPME offers several important features including (i) fast analysis by reduction of
sample preparation, (ii) minimization of the use of solvents, (iii) unattended operation
