Centrifuge for 15 min at 13,000 rpm discard the supernatant. Wash the pellet with 700μl of cold 70% ethanol to dissolve the remaining salts and dislodge from the tube wall by tapping the tube gently with your finger tips. If the pellet is white, salts may still be present. Try to disaggregate the pellet and wash again with 70% ethanol at room temperature.