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New testing methods

SASA headquartersChemists at SASA have developed a new analytical method that significantly increases the number of chemicals sought in suspected poisoning incidents

Article by SASA for PAW Scotland

04/06/2010

The chemical diagnosis of suspected pesticide poisoning incidents involving victims, baits, suspicious substances and/or poisoning paraphernalia is extremely challenging because:

  • Hundreds of professional and amateur products are commercially available and currently approved for use in the UK.
  • Products withdrawn from use in the UK are still accessible.
  • New products are regularly introduced to the market.
  • Analytical methods, techniques and instrumentation used must be capable of the detection, unequivocal identification and quantitation of the poison.
  • Analytical methods, data and records must comply with rigorous Quality Assurance procedures and data can be presented, scrutinised and challenged in associated court proceedings.
  • Targeted chemicals must be extracted from a variety of test specimens which can be of biological origin (e.g. liver) or from inanimate objects such as knives, game bags and clothing or from suspicious substances present in unlabelled containers.

SASA testing methods montage

SASA's 'Animal Poisoning' target chemical inventory had remained unchanged for over a decade. Test specimens were routinely screened for the presence of 31 different chemicals using an established multi-residue method. However, this was in stark contrast to extensive development of our 'Pesticide Residues in Food' target chemical inventory which is continuously reviewed and updated due to changes in associated EU and UK legislation and policy. Consequently, analytical methods designed for the determination of 'Pesticide Residues in Food' have allowed us to screen for over 400 different chemicals that could remain in/or on fruit & vegetables.

Consideration of the above factors and the acute need to enhance the capability of the Wildlife Incident Investigation Scheme (WIIS) surveillance program in Scotland resulted in the development of a new WIIS multi- SASA analystresidue method that utilises Liquid Chromatography-Mass Spectrometry (LCMS). LCMS exploits the ability of Liquid Chromatography to separate target chemicals from other components that may be present in the sample extract and combines it with Mass Spectrometry which provides a spectral 'fingerprint' that is unique to the target chemical.

The new WIIS multi-residue method, which took 3 months to develop, has extended the 'Animal Poisoning' target chemical inventory to 148 different chemicals, has improved sensitivity and complies with the requirements of ISO/IEC 17025:2005: the global quality standard for analytical testing laboratories.
Application of the new WIIS multi-residue method has had the desired impact (Table 1) and was formally implemented in January 2010.

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Table 1. comparison of results obtained using the 'old' and 'new' WIIS analytical methods.
IncidentSpeciesTest specimenChemicals detectedChemicals detected
Old methodNew method
09059BuzzardStomach contentNoneIsoproturon 1
LiverNot testedIsoproturon
09070CatStomach contentNoneAldicarb 2
LiverNot testedAldicarb
10002Red kiteGullet contentCarbofuran & carbosulfanCarbofuran & carbosulfan 3
10044BuzzardStomach contentCarbofuran & carbosulfanCarbofuran & carbosulfan
LiverNoneCarbofuran
10058Peregrine FalconCrop contentNot usedAldicarb & aldicarb sulfoxide 4
10070CrowStomach contentNot usedCarbofuran & carbosulfan

Caution Poison

1 Isoproturon is a herbicide (weed killer) and a new addition to the WIIS chemical inventory: UK approval expired in 2009.

2 A residue of aldicarb was identified due to improved sensitivity of the new method. Aldicarb is an insecticide and not approved for use in the UK.

3 Quantitation of carbosulfan residues using the new method is much more robust and reliable than the old method. UK approval for carbosulfan expired in December 2008. Carbosulfan can break-down and generate carbofuran.

4 Aldicarb sulfoxide is a metabolite (degradation product) of aldicarb and a new addition to the WIIS chemical inventory.