Maybe a better solution would be to add an extra column that is automatically set to 1 on each row. As soon as there is an element that is not null change it to a 0.
then
If(drEntitity.rows[i].coulmn[8] = 1)
{
dtEntity.Rows.Add(drEntity);
}
else
{
//don't add, will create a new one (drEntity = dtEntity.NewRow();)
}