The Buffer Solution Vial cap is composed of two parts (purple and white). 

Remove the entire cap. Stir the swab into the Buffer Solution, ensuring that the swab head is fully submerged by tilting the vial. 

Twist the swab back and forth 20 times in the Buffer Solution. Roll the swab head against the inner wall of the vial to release the liquid from the swab, then discard the swab.