As Yappy stated, you can use split. You should also take a look at the explode() function.
Something you might want to consider... I see that your string ends with a separator. This will result in the final value of your array being NULL. To avoid this, first trim your string, then do the explode():
$sep = "|";
$string = trim($string, $sep);
$array = explode($sep; $string);
If you ever need to put them back together, use implode().
Hope that helps!