How is cross contamination prevented between samples?
The rinsing and cleaning of the electrode, burette tips and rod stirrer after a titration is essential to avoid any cross contamination with future samples. This equipment is rinsed efficiently by very fine water droplets from three spray nozzles. The waste and rinsing solution is aspirated off completely. It is important to stress that these rinsing and aspirating times can be changed, for example, one may want to aspirate the sample totally then spray and aspirate simultaneously for say 10 seconds and then aspirate only for a further 5 seconds. Special beakers can be assigned to each separate sample rack, which enables the correct, ongoing routine electrode maintenance to take place between titrations and of course at the very end of the automated sample run.
