Why would they have had to notice this? What is it in your vast police investigative experience that would lead you to believe that all evidence is collected from a crime scene immediately?
It appears to have been handled in accordance with the procedures that I have read. However, some of the links provided by halides1 suggest there are other ways of handling evidence.
Always with the "47 days" meme. What is so magical about the number 47? Would is have made a difference if the evidence was collected 47 minutes after the crimescene was sealed? 47 hours? 47 weeks?
You may want to take up your case regarding the inadmissibility of the bra clasp with halides1. On his site, he clearly accepts that it should be admitted as evidence and that all DNA sources should be identified. In part this is because he believes one of the other DNA sources might be the real killer:
"[It] is difficult to see why the three individuals who deposited DNA on the clasp should not be considered potential suspects."
(Source:
http://viewfromwilmington.blogspot.com/2010/01/meredith-kerchers-bra-clasp.html )
It is not difficult for most of us to understand why the DNA of those three individuals were not challenged by the defence teams. They were female and one of them was almost certainly Amanda. He states as much in the comments section.
I wonder if he suspects Filomena was the real killer.