MINISTRY OF EDUCATION AND
TRAINING
VIETNAM ACADEMY
OF SCIENCE AND TECHNOLOGY
GRADUATE UNIVERSITY SCIENCE AND TECHNOLOGY
-----------------------------
Pham Tuan Linh
STUDY AND DEVELOPMENT OF QuEChERS GC/MS 3 SIM
TECHNIQUE TO ANALYSE MULTI PESTICIDE RESIDUES
IN SOIL
Major: Analytical Chemistry
Code: 62.44.01.18
SUMMARY OF ANALYTICAL CHEMISTRY DOCTORAL THESIS
Hanoi, 2019
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This thesis is completed at: Graduate University Science and
Technology – Vietnam Academy of Science and Technology.
Science instructor 1: Assoc.Prof.Dr. Vu Duc Loi
Science instructor 2: Assoc.Prof.Dr. Nguyen Hong Khanh
Reviewer 1:
Reviewer 2:
Reviewer 3:
The thesis will be presented to the scientific council
at Graduate University Science and Technology – Vietnam Academy
of Science and Technology
at …..… h .., date …… month …….. , 2019
The thesis can be found at:
- Library of Graduate University Science and Technology
- National library of Vietnam
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INTRODUCTION
1. The urgency of the thesis
Nowadays, more than1500 different kinds of pesticides have
been used, classified based on chemical structure (chlorinated,
phosphorus, Carbamate, Pyrethroid ...) or by application (insecticide,
fungicide, herbicide ...)
In Vietnam, more and more different pesticides are used in
agriculture (increased from 189 substances in 2003 to 437 substances
in 2010).
Pesticides have been known to be contaminants that persist
for a long time in the environment. So over time, there will be
residues of many different pesticide in the soil.
Pesticides accumulated in the soil can be transferred to
humans via the food chain, being potentially harmful to human
health. Thus, the level of pesticide residues in the agricultural soil
needs to be monitored as farmers switch to organic farming (green
and safe agriculture)
Currently, pesticide residues in soil is determined separately
for each substance group, with different procedures, so increasing
costs, extend the analysis time and analysis process becomes more
complicated.
Therefore, the project "Study and development of
QuEChERS GC / MS 3 SIM technique to analyze multi pesticide
residues in soil" was carried out, in order to reduce the analysis time,
minimize the number of analytical steps, use fewer reagents in
smaller amounts and provide high recovery
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2. Scope of thesis
Develop a rapid and simple method for analysis of multi-residue
pesticides, including organophosphate, organochlorine, carbamate,
and pyrethroid compounds in soil, with sample preparation based on
QuEChERS technique and determination by GC-MS.
3. Main contents of thesis
- Survey and select optimal conditions to analyze multi pesticides on
GC / MS system: injection mode, temperature program, parameters
for mass spectrometry.
- Investigate optimization of processing samples including
extraction, cleaning and enrichment: solvent and extraction time,
influencing factors, cleaning agents.
- Verification of analytical methods: determination of linear range,
calibration curve, detection limit and quantitative limit, recovery
coefficient and repeatability of the method.
- Apply the optimal procedure to analyze 30 soil samples and
compare results with 04 laboratories at Vietnam and Korea
4. New contributions of the thesis
- This is the first study in Vietnam to apply the QuEChERS method
for multi-residues pesticides analysis in the soil
- d-SPE has been applied instead of soxhlet extraction, so the
sample preparation time has been reduced from 24 h to 25
minutes, consuming only 15 ml solvent (the popular methods
consume at least 300ml of solvent)
- With a single run, 103 pesticides in soil have been analyzed (the
latest publication, only 42 pesticides in the soil were quantified)
- In quantitative step, only GC/MS is used (in publications,
GC/MS/MS is analytical method usually selected)
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OVERVIEW CHAPTER 1.
Pesticides (herbicides, fungicides or insecticides) are
environmental pollutants often found in soil, water, atmosphere and
agricultural products, and may exist in harmful levels, posing an
environmental threat. Even low levels of pesticide can cause adverse
effects on humans, plants, animals and ecosystems. The application
of pesticides has increased appreciably during the past few decades,
resulting in a potential risk for the human health. Over 95% of
sprayed pesticides reach a destination other (usually soil
environment) than their target. So, the determination of pesticide
residues in soil has been rising in demand.
The analysis of pesticide residues in soil consists of sample
preparation and the instrumental determination. The aim of the
sample preparation is to isolate the trace amounts of analytes from a
large quantity of complex matrices and eliminate the interferences
from the soil matrix as much as possible. Typical sample preparation
steps include the homogenization, extraction, and clean-up.
Due to the low concentration levels of pesticide in soil, a
technique strong enough to extract bound residues is necessary. The
most common of these techniques are mechanical agitation by
shaking, sonication, microwave energy, and liquid-solid extraction
(e.g.: Soxhlet extraction; accelerated solvent extraction, pressurized
liquid extraction, and, supercritical fluid extraction). The most
popular clean-up methods are based on the solid phase extraction
technique using florisil cartridges. These established methods are
effective, yet time consuming (taking as long as 1,5day), complicated
and expensive.
