The invention relates to a method for operating a furnace, wherein a starting material comprising at least one metal element is molten, wherein the starting material is heated by at least one burner that is operated with a fuel volume flow of a fuel and an oxidant volume flow of an oxidant. The receive rate of incoming packets varies as congestion in the network causes variation in the amount of time for a packet to traverse the network before being placed into the JAB. Each mobile station shifts to a mode periodically receiving signals from the base stations if no signals are transmitted and received for a predetermine period. This prevents the sample from remaining in the connecting part, thereby reducing sample carry-over and improving the accuracy of analysis. A bottom surface of the end cap reflects or diffuses light within the interior of the end cap inwardly with respect to the first light detector andor the second light detector.