Cannot retirieve single column from database. Laravel

I'm trying to retrieve single column from my table grades. For that I have used following code in my controller:

public function verify($id,$sid)
{

$grade=Grade::all('annual')->whereLoose('id',$id);
return $grade;

}

Where, annual is column name. But it is returning empty set of array []. Can anyone help me?

via Chebli Mohamed