Methods Used for Pesticide Residue Analysis in Estonia

1
Methods Used for Pesticide Residue Analysis in
Estonia

• Peeter Laumann, Ilona Honga, Ülle Püü
• - HPI Tartu Laboratory
• - HPI Central Laboratory
• - ECCPP Laboratory for Residues and
  Contaminants

2
In Estonia, pesticide residue analysis are
carried out in three laboratories

• Estonian Control Center of Plant Production
  Laboratory for Residues and Contaminants in Saku
  under the Ministry of Agriculture, and is
  analysing mostly samples of plant origin and
  cereals,
• Health Protection Inspectorate Central Laboratory
  in Tallinn,
• Health Protection Inspectorate Tartu Laboratory
  in Tartu, both under the Ministry of Social
  Affairs, and are analysing samples of plant
  origin, animal origin (fatty) and drinking water

3
GC multi-residue method for analysing pesticide
residues in samples of plant origin

• Used for determination of pesticide residues from
  samples of plant origin and cereals, method
  varies slightly within these three laboratories
  and the principle is
• extraction of pesticide residues from homogenized
  sample (with ethyl acetate in Tartu,
  acetone/ethyl acetate/cyclohexane in Central and
  acetone/dichloromethane in Saku Laboratory),
• GPC (SX-3) clean-up using cyclohexane/ethyl
  acetate 11 v/v as eluent,
• additional clean-up with SPE minicolumns in case
  of difficult matrices,
• GC determination,
• With this method up to 145 pesticide residues can
  be determined.

4
Saku Laboratory follows the traditional scheme
using GC-s with selective detectors (ECD, NPD)
for routine analysis and GC/MSD (EI) for
confirmation of positive findings HPI
laboratories are using GC/MSD (EI) for all
routine analysis.

• Principles of determination with GC/MSD/EI
  (quadrupole)
• Using SCAN-mode, retention time of the compound
  is located and mass-spectrum is recorded
• From that spectrum 3 characteristic m/z values
  are choosen for SIM-mode method
• Compounds are grouped by retention time and in
  every group these 3 m/z values are recorded for
  each compound
• Finally we get specific window for each
  compound, where only these 3 m/z values are
  recorded during the analyse

5
Advantages and disadvantages of using GC/MSD for
multiresidue determination

• Advantages
• Pesticides with different heterogroup and
  structure can be analysed
• Qualitative determination is more trustfull
• Analyse is less time-consuming and more
  comfortable for the chemist

• Disadvantages
• Difficulties with some pesticides
• Analyse is bit more expensive (instrument itself,
  reagents, maintenance)

6
HPLC multi-residue method for analysing pesticide
residues in samples of plant origin

• Used for determination of some pesticide residues
  from samples of plant origin and the principle
  is
• extraction of homogenized sample with alkalysed
  ethyl acetate,
• GPC (SX-3) clean-up using cyclohexane/ethyl
  acetate 11 v/v as eluent (SPE clean-up in Saku
  Laboratory)
• HPLC determination with DAD.
• With this method 4 pesticide residues can be
  determined.

7
GC multi-residue method for analysing pesticide
residues in samples of animal origin

• Used for determination of OC pesticide residues
  and some PCB isomer residues and the principle
  is
• extraction of fat from homogenized sample with
  cyclohexane,
• GPC (SX-3) clean-up of the fat using
  cyclohexane/ethyl acetate 11 v/v as eluent,
• GC/ECD for routine analyses, GC/MSD for
  confirmation,
• With this method up to 21 OCP pesticide residues
  and 7 PCB isomer residues can be determined.

8
GC multi-residue method for analysing pesticide
residues in drinking water

• Used for determination of mostly OC pesticide
  residues and the principle is
• extraction and clean-up of the sample with
  Speedisk? cartridges,
• GC/ECD for routine analyses, GC/MSD for
  confirmation,
• With this method up to 21 pesticide residues can
  be determined.

9
Spectrophotometrical determination of
dithiocarbamate residues in samples of plant
origin

• Used for determination of dithiocarbamate
  residues and the principle is
• hydrolysing dithiocarbamates to CS2 in acidic
  media,
• CS2 forming yellow complex with Cullens reactive,
• spectrophotometrical determination of the
  complex-containing solution,
• With this method sum of 5 dithiocarbamate
  pesticide residues can be determined.

10
Quality assurance

• All three laboratories are accredited according
  to ISO 17025 by Estonian accreditation body - EAK
• Tartu Laboratory was in 2000-2002 accredited
  according to ISO 17025 also by Danish
  accreditation body - DANAK, accreditation was
  canceled this winter by the request of laboratory
  due to financial problems
• All laboratories participiate in proficiency
  tests organized mostly by FAPAS and for last
  years also by EC