interface
function GetSerialNumber(const PathName: string): string;

implementation

function GetSerialNumber(const PathName: string): string;
var
SN, MCL, FSF: DWORD;
begin {GetSerialNumber}
  if GetVolumeInformation(PChar(PathName), nil, 0, @SN, MCL, FSF, nil, 0) then
  Result := Format('%x-%x', [LongRec(SN).Hi, LongRec(SN).Lo])
  else
  Result := '';
end;