[1] Northumbria Univ, Sch Appl & Mol Sci, Newcastle Upon Tyne NE1 8ST, Tyne & Wear, England
[2] AstraZeneca Ltd, Brixham Environm Labs, Brixham TQ5 8BA, Devon, England
[3] Zeneca Agrochem, Jealotts Hill Res Stn, Bracknell RG12 6EY, Berks, England
[4] Avecia, Manchester M9 8ZS, Lancs, England