How to prepare 800,000 units of penicillin skin test solution. The first step is to take one penicillin and then add 4ml of saline to dissolve the penicillin powder completely. A 1ml syringe is generally used to prepare penicillin. Use a 1ml syringe to draw 0.1ml of liquid, then draw 0.9ml of saline to prepare 1ml of solution. Remove 0.9 ml and retain 0.1 ml. Then draw 0.9 ml of saline to prepare a 1 ml solution. Remove 0.9ml again and retain 0.1ml, then draw 0.9ml of saline to prepare a 1ml solution. At this time, the penicillin skin test solution has been configured, and if a skin test is needed just inject 0.1ml into the patient’s forearm intradermally.