Agriculture Reference
In-Depth Information
in licorice root after sodium bicarbonate (0.13M) and methanol (9:1, v/v) extraction
and immunoaf
nity cleanup. A detection limit as low as 0.01 ng/g of OTA in matrix
was reported.
8.4.4
Immunochemical Methods
Immunochemical screening assays represent an important group of high-throughput
tools for analyzing mycotoxins in various biological matrices, including food and feed.
These techniques are characterized by rapid sample preparation and minimal time of
analysis [17]. Because of their high selectivity provided by speci
c antibodies, their
relative simplicity, and
field portability, immunochemical methods are widely
employed in industry and for purposes of agricultural control to obtain instant
information on contamination with mycotoxins [81,82]. The predominant immuno-
chemical techniques are based on ELISA, lateral
flow devices (LFD), and surface
plasmon resonance (SPR) technology [83]. Similar to the previously discussed
techniques, the trends in this
field are toward the development of rapid multimycotoxin
screening methods with improved detection limits, decreased matrix effects, and
simpli
ed operation [81,83]. Several comprehensive reviews have recently been
published by Zheng et al. [15], Goryacheva et al. [81] and Maragos et al. [84]. The
following sections provide an overview of current applications of and future trends in
immunochemical methods.
8.4.4.1 Enzyme-Linked Immunosorbent Assay
The microtiter plate ELISA is the most frequently applied rapid method for the
analysis of mycotoxins. Both direct and indirect ELISA kits are commercially
available for a variety of mycotoxins. The ELISA kits are usually intended for the
analysis of a
atoxins, fumonisins, trichothecenes, OTA, and ZON in cereals (maize,
wheat, and oats), nuts, milk or cheese (AFM1), and feed. The majority of studies
employing ELISA are aimed at monitoring mycotoxins in raw materials and food
products. Additionally, new synthetic antigens and monoclonal antibodies for other
mycotoxins, such as citrinin, are continuously being developed [85]. Other new
polyclonal antibodies and ELISA kits for determination of tenuazonic acid in
flour [86], trichothecene mycotoxin verrucarin A in indoor environments [87], and
a
atoxins in herbal medicine products [88] have been recently introduced.
The main disadvantage of ELISA tests is the existence of antibody cross-reactivity
to matrix or structurally related mycotoxins, which can produce overestimation or
false positive results. Therefore, LC
rmation of positive results
obtained by ELISA is often performed. Although there is good agreement between
data generated by ELISA and instrumental techniques for some matrices (cereals and
rice), this trend cannot be generalized. To provide more accurate results, each lot of
ELISA kits should be characterized by the producer in terms of cross-reactivity and
recovery and this respective information should be provided to the users and declared
on the product [89]. Currently, no ELISA kits that enable simultaneous determination
of multiple mycotoxins are available.
-
MS-based con
