save $_GLOBALS to a database field

Hello, I would like to record, on a database, the global variables $_POST and $_SERVER for each action that the user does that involves a modification of the database. I am just saving, say $_POST or $_SERVER (and others), as a string and putting it in a field on the database. However, when I try to get the info out of the database and access it as an XML (using the DOMDocument library) it becomes a pain to handle due to all the special characters (I think, as I haven't been able to get it to work), for example: Mozilla/5.0 (X11; Linux x86_64; rv:16.0) Gecko/20100101 Firefox/16.0 (I seem to need to replace all the "/"s) It's a pain, and I would like not to have to replace special characters with preg_replace if possible. Any suggestions? I have been having a lot of trouble with this. Thanks in advance, Ramiro