Page 28 - Volume 5, Issue 2, July 2012
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© Benaki Phytopathological Institute
Laboratory of Pesticide Residues, National Reference
Laboratory, Department of Pesticides Control and
Phytopharmacy, Benaki Phytopathological Institute,
8 St. Delta str., GR-145 61 Kifissia (Athens), Greece.
Corresponding author:
Hellenic Plant Protection Journal
5:
57-64, 2012
Validation of single residue methods for the determination
of dithiocarbamates and inorganic bromide residues in plant
products
E. Bempelou, K.S. Liapis and G.E. Miliadis
Summary
The use of pesticides in agricultural practice is still inevitable. However, public concern on
food safety has made the surveillance of plant products for the determination of pesticide residues ab-
solutely necessary. Multiresidue methods are usually applied for this purpose, although certain com-
pounds require specific methods, the single residues methods. Being focused on those compounds in
the present study, we validated two analytical methods for the determination of dithiocarbamate fun-
gicides and bromide ion, in plant products using gas chromatography with flame photometric detec-
tor (FPD) with sulphur filter and electron capture detector (ECD), respectively. The determination of di-
thiocarbamates was based on the release of carbon disulfide after heating of the sample with aquatic
solution of tin (II) chloride, while the corresponding for bromide ion was achieved after derivatization
to 1-bromopropanol-2 and 2-bromopropanol-1 in an acidic propylene oxide solution, and the use of
3-bromo-1-propanol as internal standard for quantification. Validation parameters, namely trueness,
precision, sensitivity and linearity were evaluated for both methods and validation procedures were
carried out at 2 to 3 concentration levels with 5 replicates each according to the requirements of SAN-
CO Document 10684/2009. The highest level of validation was that of the EU MRL, while the limit of de-
termination was the successful lowest validated level. The two methods are characterized by good ac-
curacy, precision and sensitivity and are considered as suitable for routine analysis in accordance to the
requirements of the European Commission.
Additional keywords
: dithiocarbamates, inorganic bromide, residues
most usually perfomed by application of
multiresidue methods. However, there are
certain compounds that are not suitable for
multiresidue determination, as they have
physicochemical properties significantly dif-
fering from the majority of pesticides. These
compounds need specific methods for their
determination, the single residue meth-
ods (SRMs). The validation process for each
of those methods in representative matri-
ces provides the evidence that the meth-
od is fit for purpose. Bromide in agricultur-
al products is appearing as the degradation
product of various fumigants, mainly meth-
yl bromide ion. It is therefore required to de-
termine by a SRM the total bromide residues
in its inorganic form, i.e. bromide ion. Dithio-
carbamates on the other hand are not stable
at the extraction step used in multiresidue
analysis and therefore require an SRM.
Introduction
The widespread consumer concern for food
safety and quality has highly increased now-
adays and pesticide residues in agricultural
commodities have been the subject of strict
regulations. Certainly, the use of pesticides
according to good agricultural practices
(GAPs) is not expected to cause problems of
public concern in health and environmen-
tal areas. However, in the case of inappropri-
ate treatments undesirable residues can be
detected on vegetables or other plant prod-
ucts after harvest.
Pesticide detection in plant products is
