The 800,000 unit penicillin skin test solution is prepared by first taking a penicillin and then adding 4 ml of saline to completely dissolve the penicillin powder. Usually a 1ml syringe is used to prepare penicillin. A 1ml syringe is used to draw 0.1ml of liquid and then 0.9ml of saline to prepare a 1ml solution. Remove 0.9 ml and retain 0.1 ml. then draw 0.9 ml of saline to prepare a 1 ml solution. Another 0.9 ml is removed, 0.1 ml is retained, and another 0.9 ml of saline is withdrawn to make 1 ml of solution. At this time the penicillin skin test solution has been configured, if you need to do a skin test on the patient’s forearm intradermal injection of 0.1 ml can be.