HPLC CHROMATOGRAPHY HINTS and TIPS FOR CHROMATOGRAPHERS [HPLC Feb 28, 2015 · (3) Wash Vial Usage and/or Sample Vial Selection: If you are using a modern high-pressure, “Flow-Through” design autoinjector (e.g. Aijiren , , , ), then carryover is rarely an issue as these modern injectors use a high pressure pump to aspirate and inject the samples directly into the flow path