How about using some standard SQL string compariuson functions/operators? Like "<>", "LIKE", "INSTR" - you choose one. Something like:
Code:
...
if l_buffer LIKE '#%' then
  insert into TEST ...
end if;
...
or
Code:
...
if INSTR(l_buffer,'#') > 0 then
  insert into TEST ...
end if;
...
or ...... I mean, totaly basic SQL functions/operators.