26 Handbook of herbs and spices
permissible levels therefore the method selected to be used must have appropriate
sensitivity. In addition, having short analysis time, ease-of-use, being a reliable, less
interfering, and inexpensive substance are other important factors (Ahmed, 2000;
Lombaert, 2002).
The technical infrastructure of the laboratory is also very important for the selection
of the method. For example, thin layer chromatography (TLC) can be considered as
an appropriate method due to its low initial investment. However, the application and
evaluation of the method is very difficult. Evaluation should be made with a densitometer.
Thus the visual errors in the determination of the equivalent mycotoxin to the standard
should be eliminated. During an interlab study with 28 participating laboratories, on
DON analysis of agricultural products, it was reported that the results from TLC were
considerably lower than the average value (p = 0.01) (Josephs et al., 2001). In fact,
thin layer chromatography is suitable for confirmation of positive samples (De Nijs
and Notermans, 2000).
Almost all analytical procedures consist of the similar basic steps which include:
∑ extraction
∑ purification and clean-up
∑ separation, detection and determination
∑ confirmation.
Not all methods for mycotoxins in foodstuffs incorporate a cleanup step. In particular,
ELISA methods may not require any cleanup (Scott, 2002). However, Yu et al.,
(1998) developed and used immunoaffinity columns (IAC) for the cleanup of CPA
extracts prior to ELISA analysis of corn, peanuts, and mixed feed (Dorner, 2002).
ELISA is a useful tool for screening purposes before LC or GC.
The analytical methods for mycotoxins include thin layer chromatography (TLC),
high performance liquid chromatography (HPLC) or reversed phased liquid
chromatography (LC), enzyme-linked immunosorbent assay (ELISA), and, more
recently, by tandem mass spectrometry (MS) (Scott, 2002; Trucksess, 2000; Ventura
et al., 2004). Aflatoxins, ochratoxin A, deoxynivalenol and zearalenone can be
determined by fluorescence detection after chromatographic separation (De Nijs and
Notermans, 2000). Gas chromatography (GC) has also been used for many mycotoxin
analysis especially for the identification and quantification of multiple trichothecenes
in foods (Lombaert, 2002).
Capillary electrophoresis (CE) may be used as an alternative technique to analyse
mycotoxins (Cancalon, 1995; Martin et al., 2005). A particular type of CE, micellar
electrokinetic capillary electrophoresis or micellar electrokinetic capillary
chromatography (MECC) has been used for aflatoxin, cyclopiazonic acid, citrinin,
griseofulvin, mycophenolic acid, ochratoxin A, patulin, penicillic acid, and
sterigmatocystin analyses (Cancalon, 1995; Martin et al., 2005). The method has
several advantages such as more rapid analysis, reduced amount of organic solvents,
smaller sample volume, and increased efficiency and resolution (Martin et al., 2005).
According to a survey of the literature, HPLC was the leading approach, followed by
TLC and ELISA in mycotoxin analyses in herbs and spices (Table 1.1). In addition,
a single study was found on liquid chromatography-tandem mass spectrometry in
medicinal herbs in the literature (Ventura et al., 2004).
Ventura et al., (2004), extracted aflatoxins in Rhammus purshiana which is a
medicinal herb, with methanol:water and tested by liquid chromatography and detected
by mass spectrometry single quadruple using an electrospray ionisation source (LC-