Oz wrote:

Just to give you some idea I have visited a site where they could test
at these levels. They had three areas, with separate doors to the
outside and staff from each area were not allowed to touch each other
until their shift had finished. This was because if one of the 'low
level detection' area walked through the 'high level' area (where the
test applications were made) then they would totally trash the analysis
just from particles they picked up walking through.

This doesn't make sense. Analytical labs which are set up to detect extremely
small quantities of substances have to keep the samples isolated from all
possible contaminants and that will include keeping them isolated from
contamination by the people who are working on them.

Also it doesn't require particularly sophisticated equipment or test conditions
to detect pesticides on at the levels which are present on vegetables which are
purchased by consumers. A gas chromatograph fitted with an electron capture
detector will do it for many although combined gas chromatography/mass
spectrometry may be required for unequivocal identification of some compounds.

--
Mike Humberston
Barnes, London

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