Agriculture Reference
In-Depth Information
its production and by-products of food technologies are frequently contaminated. For
instance, the occurrence of
Fusarium
mycotoxins was reported at high concentrations
in samples of dried distiller
s grains with solubles (DDGS). This material represents a
valuable by-product of the ethanol production process and is used for feeding
livestock. Last but not least, mycotoxins are also analyzed in nonfood/feed biological
matrices, such as urine, blood, and feces to monitor their occurrence and metabolic
transformations
in vivo
[22,23]. Given this range of target analytes and matrices, it is
clear that no single extraction process will be optimal for all analytes in all matrices.
Therefore, a range of extraction techniques have been developed, differing in their
speci
'
city, complexity, and speed. In Section 2.3, we discuss several common
extraction protocols.
8.2.3 Extraction of Mycotoxins
The use of optimal extraction procedures is dictated by the physicochemical properties of
the target mycotoxins and the matrix they are in. Similar to other contaminants discussed
in this topic, solid
liquid extraction (SLE) is the most frequently applied approach to
extract mycotoxins from sample matrices. The choice of suitable extraction solvents is
crucial to ensure suf
-
cation. In procedures that
aim to isolate only a single analyte or a small group of related mycotoxins, the
composition of the extraction mixture can be adjusted for optimum recovery. Never-
theless, with regard to current trends aimed at the simultaneous determination of
numerous mycotoxins, which largely differ in physicochemical properties, solvent
mixtures allowing generic extraction of analytes are required. A number of extraction
solvents, including methanol, chloroform, acetone, ethyl acetate, and acetonitrile, and
their mixtures have already been employed for the extraction of mycotoxins. Among
various solvent combinations, themixture of acetonitrile andwater in ratios ranging from
84:16 to 75:25 (v/v) represents the most ef
cient recoveries, and thus accurate quanti
cient extraction solvent commonly used.
Additionally, in order to improve recoveries of some acidic mycotoxins, formic or acetic
acid is frequently added to the extraction mixture [4,5,17,18]. The generic extraction
strategy called
“
dilute-and-shoot,
”
which uses only pure solvents without any further
puri
cation, is nowadays commonly applied for the extraction of a wide range of
mycotoxins [24]. The ef
ciency of extraction is usually improved by integrating shaking,
sonication, or mixing into the extraction procedure. Alternatively, a combination of the
above techniques is used.
Among various methods for the extraction of mycotoxins described in the
literature, the QuEChERS (i.e., quick, easy, cheap, effective, rugged, and safe)
protocol is probably one of the most relevant to high-throughput analysis. Since
its original introduction for pesticide residues analysis [25], QuEChERS has already
been used in numerous modi
cations to extract other chemical contaminants from
various food matrices [26]. The QuEChERS procedure combines sample extraction
from a mixture of an organic solvent (usually acetonitrile) with water and transfer of
analytes into an organic layer with simultaneous separation of aqueous and organic
phases induced by the addition of salts. The crude organic extract can be subsequently
puri
ed with the use of dispersive solid-phase extraction (dSPE) to remove undesired
