Solid phase methods for the identification of an analyte in a biological medium, such as a body fluid, using bioluminescence are provided. 06 to 4% by weight of dissolved tetramethylammonium hydroxide, the weight percentage being based on the complete weight of the respective test solution, a constant removal rate at 50\xb0 C. The engagement system is attached to the airframe and is capable of engaging the physical connector system to connect the number of battery pods to the airframe. The inlet port is positioned below the elongate vertical portion and the outlet port is positioned below the flared portion such that bodily liquid traveling from the inlet toward the outlet is forced around the flared portion to cause air bubbles in the bodily liquid to be re-circulated back toward the inlet port. An arrangement for determining an instantaneous position of the tap comprises a first evaluation circuit designed to determine a first measurement value representative of the first partial impedance, and a second evaluation circuit designed to determine a second measurement value representative of the second partial impedance.