During the conduct of an OECD 106 Adsorption – Desorption using a Batch Equilibrium Method study, an additional peak in the HPLC data was identified by Joanne Gilbert, Environmental Fate Study Director, from the Smithers Harrogate laboratory in the UK.
Using LC-MS/MS, the component of the new peak was determined to be an isomer of the parent compound. It was noted that the isomer was only present in samples that had spent some time exposed to lab lighting, other variables were controlled. To determine if the laboratory lighting was indeed the cause of the isomerization Joanne evaluated isomer formation in the presence of standard laboratory light. Samples stored in the dark did not contain detectable amounts of the isomer whereas in the presence of standard laboratory lighting isomerization occurred, The isomerization in light can be exacerbated by the presence of soil.
The investigation provides reason for caution regarding isomerization of test material under standard laboratory conditions, especially in light of the new guidance from EFSA regarding the evaluation of plant protection products that contain stereoisomers.
To learn more about this topic or to see an overview presentation of Joanne's research for SETAC Europe, visit our poster presentation page.