Hi Catherine,

If the patient information leaflet and ICD detail this I think it should be fine - as these documents will receive ethical approval, and the REC will raise any concerns they have with you. The key would be that the data or samples used should be anonymised for any future use and this should be explained to the volunteer. It's very unlikely that future use would receive ethical approval if patient identifiers were to be included without consent.
A separate generic consent document isn't unworkable, but a simple paragraph in the ICD should suffice.

Best wishes,

Rob