$re = '/ \s*(( )?[0-9]+(?:\.\d+)?(?:\s*(?:l[ lb ]|lb))?(, )?)+\b/';
$str = '<br><span style="font-size: 15px;"><span style="color: #000000;">• 8.5 lb, 25.4 lb 8.5 lb, 25.4 lb 8.5 lb, 25.4 lb</ ';
preg_match_all($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