PHPID: 35688476100

$str = '"nama : ratna","umur : 19",
"nama : dono","umur : 20",
"nama : santi","umur : 13",
"nama : alexande agung","umur : 31",
"nama : subroto hadikusumo","umur : 22"';
$arr= explode(',', $str);
foreach($arr as $vars){
    $e = explode(':', $vars);
    if(trim($e[0])=='"nama')
        $data[] = $vars;
}

echo implode(', ', $data);