Pesticide Analytics: Sample Preparation

Pesticides

Pesticide Analysis - An important building block in the quality assurance of foodstuffs

Pesticides are plant protecting products and products for combating parasites. They are used in agricultural cultivation or after the harvest as, among other things, insecticides, herbicides or fungicides to protect the crop and the harvested materials from parasites, weeds and fungal infestations and from decay in general.

In Switzerland, the maximum levels of pesticides are regulated by the Ordinance of the Swiss Federal Department of Home Affairs (EDI) on Foreign Substances and Ingredients in Food Products (FIV). Depending on the category of product and on the pesticide, special limit values exist for Switzerland, or reference is made to the European Regulation No. 396/2005, whose maximum levels are interpreted as being tolerance levels according to the Ordinance on Foreign Substances and Ingredients in Food Products (FIV) in Switzerland.

Pesticides must, in accordance with the Swiss legislature, be present in or on foodstuffs only in harmless and technologically unavoidable quantities. To guarantee the safety of your foodstuffs, the product-specific legal regulations must be complied with. Expertise and competent consultation are an indispensable part of this.

Are you looking for an accredited contract laboratory in Switzerland to test the safety of your products? Do you want to know if your products are marketable in relation to their pesticide residues? 

Using the most modern GC/MS-MS and LC/MS-MS techniques, we will analyse your products for more than 400 different pesticides – quickly, competently and reliably. Investigation for specialised individual pesticides is also possible.

 

We will be happy to advise you.

Read on here for more information or contact us.


What is understood to be a pesticide?

The use of pesticides can protect the crop from herbivores and parasites
The use of pesticides can protect the crop from herbivores and parasites

Currently more than 1400 chemical active substances are included in the group of pesticides. They can be divided according to their intended purpose or according to their chemical classification.

Distinctions are made chemically between polar and non-polar substances. Their structure has a direct influence on their degradation time (in respect of the retention period) in the environment and hence also on the possible accumulation path and concentration intensity in the food chain. For the foodstuff industry, organochlorine pesticides, organophosphoros pesticides, synthetic pyrethoids, pesticides containing nitrogen, phenyl urea pesticides, carbamates and a diverse range of individual substances play a particularly important role.

In practice these are often referred to as herbicides, insecticides, fungicides, acaricides, growth regulators, preservatives, synergists and seed treatments.

Why are pesticides used?

Pesticides are used primarily as plant protection products and to combat parasites. The sustainable protection of plants is in the foreground here. Avoiding loss of yield in agricultural production due to a diverse range of parasites, micro-organisms and weeds is an applied science and helps to guarantee the food supply. At the same time, the use of plant-protecting active substances also minimises further reaching risks to health such as the contamination of foodstuffs with mycotoxins.

The problems arising from pesticide residues in the food chain

Minimisation of pesticide residues should be strived for, but sometimes “cocktails of active substances” must be used to provide comprehensive protection for the product.
Minimisation of pesticide residues should be strived for, but sometimes “cocktails of active substances” must be used to provide comprehensive protection for the product.

Pesticides generally exhibit a defined acute and chronic toxicity. They are partially accumulated in the human body and can as a result be harmful to health. In the food processing industry, the principle of minimisation is strived for: “As much as necessary, but as little as possible.”
A minimisation of the resides is required to reduce the risks to health.

This basic principle is in reality fairly hard to put into practice. Because individual pesticides exhibit a high level of selectivity, so-called “active-substance cocktails” must be used for a variety of product groups to protect the products comprehensively against the many types of infestation that could occur at the same time.

This can then cause problems for the consumer, if too high levels of an active ingredient, or limited amounts of too many different active ingredients remain in the parts of the product that are intended to be consumed. This is the case if the active ingredient cannot be degraded quickly enough by the plant, or if it is not removed sufficiently from the raw products by the cleaning process.

The foodstuff industry is aware of this and, as a result, more stringent standards have been introduced internally, primarily by the retail trade in collaboration the producers and product manufacturers to protect the consumer. UFAG LABORATORIEN functions as a supportive force for the efforts of the industry and can provide support as a competent partner. The outstanding expertise is shown not only in the usage of scientifically and technically modern methods and devices, but also in the reliable and competent evaluation of analysis results according to the currently applicable legal regulations and technical knowledge.

Foodstuff safety: Statutory regulations

A contamination or an inferiority of the product is present when the tolerance value of the foodstuff has been exceeded. If however a limit value is exceeded, then the foodstuff is considered to be unfit for human consumption and is, as a result, not marketable.

This is regulated by the Swiss Federal Department of Home Affairs (EDI) in their Ordinance on Foreign Substances and Ingredients in Food Products (FIV) in which the respective tolerance and limit values for evaluation of the product for different foodstuffs can be found. Reference is often made to the European Regulation No. 396/2005, whose maximum levels are assessed as being tolerance levels in Switzerland. Fundamentally, in the evaluation of pesticides, the individual substances are assessed in a product-specific manner.

The foundations for the legal tolerance and limit values are the scientific risk assessments that are based on internationally harmonised concepts. Toxicological risks can be estimated from the results of extensive animal studies and these can be translated into so-called ADI (acceptable daily intake) values and an ARD (acute reference dose). The ADI gives information about the concentration that is seen as being harmless when the product is consumed on a lifelong basis. The ARD however defines which concentration must not be exceeded at any time.

Indirect sources of entry

Cross-contamination from pesticides is possible when pesticides are used on neighbouring fields and transfer occurs
Cross-contamination from pesticides is possible when pesticides are used on neighbouring fields and transfer occurs

Producers and distributors sometimes wonder how specific pesticides could possibly get into their products, when these pesticides are not used in their processes.

The following indirect sources of entry could possibly be the reason for this.

  • Pesticides can get into animal products from fodder
  • Quaternary ammonium compounds (QACs) can be spread from disinfectants used for cleaning facilities and can get into fresh fruit and vegetables For milk products, entry is possible directly via the milk (e.g. teat disinfection)
  • Glyphosate which accumulates in the ground and is absorbed by a number of different plants during growth
  • Perchlorates from organic fertilisers
  • Cross-contamination from pesticides being used in neighbouring fields
  • Cross-contamination during transportation

What are the challenges for pesticide analysis?

As a result of the globalisation of the foodstuffs market, the monitoring of foodstuffs for pesticide residues and their degradation products faces particular challenges. This can affect products imported from NON EU countries as there may be partially different legal regulations in their respective lands of origin.

It is possible that pesticides are used that are not permitted in Switzerland or in the EU – or that the limit value for pesticides that are authorised is exceeded. This particularly affects agrumes, exotic foods and vegetable products.

To guarantee the highest possible level of product safety, multi-methods are used to investigate the pesticides named in the Swiss Ordinance on Foreign Substances and Ingredients in Food Products and in the EU Regulations.

Methods of analysis

The list of known pesticides is continually being increased to include additional substances. To guarantee the safety of a foodstuff, it is important to use a wide range of analyses. A suitable spectrum of methods must cover all relevant pesticides and this must be regularly expanded to include new substances.

Multi-methods

Sample preparation for pesticide analysis
Sample preparation for pesticide analysis

A variety of pesticides and pest control products can be investigated with so-called multi-methods. Depending on the sample matrix, different methods of processing are used: e.g. The QuEChERS method for foodstuffs that contain little fat (<10 %) or DFG S19 for high fat foodstuffs or raw materials.

Afterwards, analysis is performed using the GC-MS/MS and LC-MS/MS method.

Individual methods

Individual methods are necessary for a few, mainly highly polar compounds. They require particular analytic conditions and cannot be measured within a multi-method. The reason for this lies either in the extraction method which is not compatible with multi-methods, or in the detection (e.g. longer measurement times or other chromatographic conditions).

Control parameters that are recorded with individual methods

Compounds Use Foodstuffs
Bromide Insecticides Salads, tomatoes, peppers, cereals
Methyl bromide Preservatives Cereals
Phosphines  Preservatives Cereals
Chlormequat/mepiquat Growth regulators Cereals, tomatoes, carrots, wine
Dithiocarbamate Fungicides Fruit, vegetables, cereals
Ethephon Growth regulators Apples, cereals, citrus fruits
DDAC, BAC Quaternary ammonium compounds (tensides, disinfectants) Bananas, mangoes, citrus fruit
Glyphosate Herbicide Cereals
Fenbutatine oxide Acaricide Apples, tomatoes, cereals, citrus fruit

 

 

Examples from the EU Regulation No. 788/2012

 

Matrix-specific requirements on pesticide analysis: e.g. in baby foods

In both the Swiss Ordinance on Foreign Substances and Ingredients in Food Products (FIV) and its European equivalent, the Commission Directive 2003/13/EC, very low tolerance and limit levels for pesticides in the range of 0.003 - 0.010 mg/kg were passed, for the protection of infants and small children. Compliance with and monitoring of these limits in raw materials and end products accordingly is difficult. Here as well, only through the use of the latest methods of analysis can the necessary sensitivity of detection and safety of the results be achieved. Suitable LC-MS/MS and GC-MS/MS systems guarantee selective detection of the substance and its quantification. There are also specific requirements on the determination limits of the investigated parameters in the analysis of pesticides in organic products. Additional products and foodstuffs also require different methods of analysis (e.g. fats and oils). Please feel free to contact us if you have any questions.

For reliable test results: Recommendations for taking the sample

Samples from a variety of vegetables and fruits for pesticide determination
Samples from a variety of vegetables and fruits for pesticide determination

To obtain reliable test results, there is more to be done that just the technically correct implementation of the analysis. Great importance should also be placed on suitable sampling methods. Many products are subject to regulations on how representative sampling should be achieved.

Things to be avoided include selective sampling from just one carton or just one location, e.g. when testing for quality is being performed on a complete shipload or from a single field.

A representative and sufficient sample size is a requirement for a meaningful and significant result. In connection with this, it should be ensured that individual component parts are analysed separately from each other. So for example, if a mixture of vegetables is being offered for sale, the individual vegetables must be checked for their marketability in relation to their pesticide contents. Therefore, for each individual product, there must be a sufficient sample size available (typically approximately 1 kg).

Who should have tests carried out?

Agricultural companies and foodstuff producers should have tests for pesticides carried out:

By testing the produced foodstuff for pesticides, consumers and intermediary distributors will be shown that the legal regulations have been complied with.

Testing for pesticides by distributors, suppliers and the food trade:
By performing testing, it will be documented that the product is purchased, supplied and sold again at a consistently high quality and that all of the legal regulations have been conformed with.


Our services in detail:

Determination of pesticides using GC
Determination of pesticides using GC
  • Consultation on the determination of pesticides
  • Testing for polar and non-polar pesticides using QuEChERS multi-method
  • Testing for sprout inhibitors
  • Testing for growth regulators
  • Testing for individual pesticides upon suspicion
  • Additional services are according to the directory of services or upon request

contact person

sales for foodstuffs

Jörg Freudenberger State Certified Graduate Food Chemist

Tel. +41 58 434 42 00 Fax +41 58 434 42 01 service@ufag-laboratorien.ch

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