Investigations of the feasibility of producing a new natural matrix reference material for the analysis of pesticide residues in products of plant origin [Elektronische Ressource] / vorgelegt von Helena Saldanha

Your User Name

Informations

• Publié par: universitat_duisburg-essen
• Publié le: 01 janvier 2011
• Nombre de lectures: 50
• Langue: English
• Poids de l'ouvrage: 2 Mo

Extrait

Investigations of the feasibility of producing a new
“natural” matrix Reference Material for the analysis of
pesticide residues in products of plant origin







Dissertation
zur
Erlangung des Doktorgrades
des Fachbereiches Chemie
der Universität Duisburg-Essen
(Dr. rer. nat.)





vorgelegt von
Helena Margarida Saldanha
Coimbra, Portugal



Essen, November 2009


ii
This work was submitted on November 2009 and was accepted on the
11.06.2010 by the department of chemistry of the University of Duisburg-Essen,
Germany. The oral defence will be on the 7.7. 2010.



Vorsitzende(r): Prof. Dr. E. Spohr

1. Gutachter(in): Prof. Dr. A. Hirner

2. Gutacher(in): Prof. Dr. H. Emons







This work was carried out at the Institute for Reference Materials and
Measurements (IRMM) of the Joint Research Center (JRC), RM unit from
September 2005 - August 2008 and was financially supported by the
Commission of the European Communities.


I, Helena Saldanha, declare that this dissertation represents my own work,
except where due acknowledgement is made.

Helena Saldanha
________________________________________________Acknowledgements__
Dedicated to my Dear Parents, and to all my journeys back Home



Thank to the following persons, was this work possible to be initiated and carried out at IRMM, Geel,
Belgium. Still much in the R&D of CRM for pesticides in food matrices needs to be addressed and
accomplished.
Their academic support and personal sympathy lead me during my stay in Flanders and avoided me
slippery in the laboratory. Each one of them contributed in many ways both in my professional life and
personality.
My academic supervisors Prof. Dr. Hendrik Emons, Prof. Dr. Franz Ulberth and Prof. Dr. Alfred Vitalis
Hirner showed me by their example a way to lead independent scientific research. Their discussions and
patiente conversations fruitfully lead us to find a possible solution for every challenge we had to face.
In a later stage of this thesis work, the comments of Dr. Heinz Schimmel added a much value to it.
To Dr. Reinhard Zeleny and Dr. Jens Boertz, of the RM unit of IRMM for comments and final revisions.
In a everyday basis, Ing. Berit Sejeroe-Olsen, scientific knowledge on the GC instrumentation and
troubleshooting ally to her great ability to deal with her co-workers kept my motivation. Here I include all my
colleagues of the RM unit who filled my days with joy, in a context of freedom with personal responsibility to
make good use of it!
My grateful thanks to three pesticide experts, Dr Katerina Mastovska, Dr Darinka Stajnbaher, and Dr
Michaelangelo Annastassiades, whose encouragement and contribution helped this work to grow.
My stay abroad was always supported by the affection of my parents, my brother Pedro and my two
nieces, Catarina and Leonor, whose smiles fills our hearts. Maria, Te, Tio Ze Branco, Vasco. They patiently
await my every time return home.
In my thoughts are all those friends living abroad with all our memories. Carmen, Helena, Irene,
Marcella, Manoel Nogueira, Paola, a special though for you. A honor in the memory of my Grandparents,
Bernard A. Van Antwerp and Daniel Nazare, for their lively and courageous faith. To Ing. Ana Veiga de Macedo
and Ing. Celina Esteves Marques and their respective families, my former colleagues in Oporto who became the
close friends who never ask why.
I am also grateful to my past professors who always helped me to live and growth, with their lives and
experience. In chronological order from when I knew them, Prof. Ing. Cristina Luisa a friend since the
propedeutic year in Oporto, Catholic University of Portugal, School of Biotechnology. Prof. Dr. Shri K. Sharma,
Cornell University for all his willingness to learn from his young fellows and who have provided all the
conditions for an enriching, adventurous and enjoyable stay at Cornell Campus, Ithaca, USA and Prof. Colomba
Di Blasi with whom I spent three years at Universita Degli Studi di Napoli, Faculty of Engineering. A tribute for a
wonderful professional and brave person in guiding young scholars.
I cannot forget those often personal words of my Godparents, Tatyana Bonifacio, Edna Diaz, Dra
Dalila Lello Pereira da Costa, Dr Simoes and Maria de Fatima Leal, who all sits in the bay of Oporto.

“Bear in mind that the wonderful things you learn in your schools are the work of many generations, produced by
enthusiastic effort and infinite labor in every country of the world. All this is put into your hands as your inheritance in
order that you may receive it, honor it, add to it, and one day faithfully hand it to your children.
Thus we mortals achieve immortality in the permanent things we create in common.”

Albert Einstein in “address to a group of children, 1934”


_________________________________________________Table of Contents___
Table of contents

1. Introduction
1.1 History 2
1.2 Classification and toxicity of pesticides 3
1.3 Effects on the environment 5
1.4 Natural pesticides from plants and the future role of pesticides in agriculture 6
1.5 Physico-chemical characterization and environmental fate of pesticides 6
1.6 Legal framework regulating the analysis of pesticides in fruits and vegetables 15
within the European Union
1.6.1 EU coordinated monitoring programme 19
1.6.2 Monitored products/active substances 19
2 Determination of pesticide residues in food matrices-
-state of the art
2.1 Food matrix 24
2.2 Physico-chemical properties of pesticides 24
2.3 Solvents used as extractants in multi-residue methods for pesticide analysis. 25
2.4 Solvents and pesticide reference standards 28
2.5 Extraction procedures 29
2.6 Cleanupprocedur31
2.7 Analysis 33
2.8 Matrix effects 34
2.9 Injection techniques and its effect on matrix enhancement 37
2.10 Detection 39
2.11 Mass analyzers 39
2.12 Ionization techniques 40
2.13 Requirements for confirmation by mass spectometry 40
2.14 General requirements for quantification 42
2.15 Quality assurance/quality control aspects in pesticide residue analysis 43
2.16 Principal definitions and terminology related to reference materials 44
2.16.1 Reference Material (RM) 47
2.16.2 Certified Reference Material (CRM) 47
2.16.3 Metrological traceability 48
i ______________________________________________Table of Contents____
2.17 Development of a food based CRM 49
2.18 Commutability 55
3 Aim of the work
4 Experimental
4.1 Chemicals and consumables 61
4.2 Test materials 63
4.3 Analytical equipment 63
4.4 GC/MS operating conditions 64
4.5 Material processing equipment and operation conditions 65
4.6 Safety precautions and protection of the environment 66
4.7 Analytical procedure 66
4.7.1 First extraction step 68
4.7.1.1 Weighing 68
4.7.1.2 Solvent and ISTD addition 68
4.7.1.3 Extraction 69
4.7.1.4 Second extraction step and partitioning 69
4.7.2 Cleanup 70
4.7.2.1 Cleanupwith amino–sorbent ("Dispersive SPE" with PSA) 70
4.7.2.2 Cleanup with a mixture of amino–sorbent+GCB ("Dispersive SPE" with PSA + GCB) for 70
samples with high content of carotenoids or chlorophyll
4.7.2.3 Extract storage 71
4.7.2.4 Concentration of the end extracts and solvent exchange 71
4.7.3 Test for interference and recovery 72
4.7.4 Evaluation of results 72
4.7.4.1 Identification and quantification 72
4.7.5 Calibration 73
4.7.5.1 Preparation of individual stock and working standard solutions 73
4.7.5.2 Solvent–based calibration standards 74
4.7.5.3 Calibration in matrix 75
4.7.5.4 Calculations of the result 75
4.7.5.5 Measurement uncertainty 77
4.7.6 Measuring sequence and performance qualification. 78


______________________________________________Table of Contents____
5 Results and Conclusions
5.1 Optimization of the analytical method for the determination of pesticides in food 80
matrices
5.1.1 Method set-up 80
5.1.2 Calibration in solvent 83
5.1.3 Matrix interferences 88
5.1.4 Extent of matrix effects 94
5.1.5 Analyte protectants (AP) 100
5.1.6 LOQ/LOD 105
5.1.7 In-House method validation 106
5.1.7.1 Performance criteria 107
5.1.7.2 LOD/ LOQ 108
5.1.7.3 Calibration 108
5.1.7.4 Recoveries 112
5.1.7.5 Method repeatibility and Intermediate precision 117
5.1.7.6 Robustness 119
5.1.7.7 Stability of the extracts 119
5.1.7.8 Stability in solvent 123
5.1.7.9 Selectivity 122
5.2 Uncertainty budget 125
5.3 General conclusions 126
5.4 Remarks In-house validation 126
6 Trace analysis of EU priority pesticides in carrots baby
food by isotope dilution mass spectrometry: (matrix
effects) and uncertainty evaluations
6.1 Recoveries native/labelled compound 137
6.2 Conclusions 138
7 A natural matrix (carrot/potato baby food) candidate
Reference Material
7.1 Introduction and char