Validation of cleaning of the sampler

Hi everyone!
Can anyone tell me how I can spend validation of cleaning of SAMPLER?
The sampler is used to selection of active substances and accessory materials (in all about 100 items).
What approaches can I used to define: critical product and acceptance criterion of its residual content?
Or in other words, how I can carry out of risk assessment of pollution of next active substance or accessory material?
Perhaps, someone of you faced with this problem.

I apologize for the bad English!