$re = '/(?i)[0-9a-f]{8}-(?:[0-9a-f]{4}-){3}[0-9a-f]{12}/m';
$str = 'f36b9decc73e40bfb9a6250198a83fc0/SharePoint/source_28D4CE4DFC53AABB34B41E17BE9DEBBC/item__6761c90b-c1e0-4a91-b72c-e044e5b8cc56_1.0
F36B9DECC73E40BFB9A6250198A83FC0/SHAREPOINT/SOURCE_28D4CE4DFC53AABB34B41E17BE9DEBBC/ITEM__6761C90B-C1E0-4A91-B72C-E044E5B8CC56_1.0';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php