A molybdenum-based precipitate is prepared according to a process including the first step of forming a crude precipitate by pH adjustment to 6. Two ends of the tube are transfixed respectively with a USB flash disk and an LED illuminating assembly. The seat 20 comprises a first part 32 projecting forwards with respect to the horizontal axle 24, and a second part 30 projecting towards the underframe 12. The first diffusion layer has a surface on which a second contact region connected to a reference voltage terminal is formed. The technician retrieves a urine sample in a sample cup, seals it, and disposes of the used collection unit.