$re = '/\b(?:(?:[CDEFGAB](?:b|bb|m)*(?:\#|\#\#|sus|maj|min|aug)*[\d\/]*(?:[CDEFGAB](?:b|bb|m)*(?:\#|\#\#|sus|maj|min|aug)*[\d\/]*)*),?)+(?=\s|$|(?:<.*>))(?![[:blank:]]\w)/';
$str = 'G,C,D
A,B,C
E,C,D';
preg_match_all($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