Hello! Hoping someone has some ideas on a new problem we've been having. We are an environmental lab that runs EPA 200.8 with no He for drinking waters. This method is working. However when we use He mode for our other methods we cannot get it to calibrate. One or more internal standards just splits off way out of range during calibration. We have replaced pumped tubing and tubing going to and from the connector block. Cleaned the torch, nebulizer, cones, and ion lenses. Purged the cell for 30 minutes. Anyone have ideas or tips??