How to convert from a string to object attribute name?

I am trying to convert a string value into a name of an attribute that belongs to an object. For example, in the following code, I need all the string values in the column_array turned into attribute names. The names "student_identification", "email", etc. are actual column names of my Student table. In the real scenario, column_array will be set by the user (by ticking check boxes). And new_array will be replaced by csv, as I want the data go into a csv file.

At the moment I am really struggling at the following line:

   new_array << r."#{column_array[i]}"

I want "#{column_array[i]}" to be turned into the attribute name so I can access the data.

def exp_tst

  @records =  Student.find(:all, :conditions=> session[:selection_scope],
                                 :order => sort_order('laboratory_id'))

  column_array = ["student_identification", "laboratory_id", "email", "current_status"]

  new_array = Array.new()

  @records.each do |r|

    (0..(column_array.size-1)).each do |i|
       new_array << r."#{column_array[i]}"
    end
  end

end