PLpgSQL FOR IN EXECUTE question

Consider the following PLpgSQL code fragment

FOR this_record IN
EXECUTE ''SELECT ''       || quote_ident($1)       || ''FROM ''       || quote_ident($2)
LOOP   list := list || '', '' || this_record.$1 ;
END LOOP;

As expected, accessing a field via this_record.$1
does not work.
Can it be done otherwise?

Regards, Christoph