"To obtain a sample" means to get or gather a small portion or representation of something. It could be collecting a small amount of liquid, substance, or data for testing or analysis. Full definition
Or an employee in a biological laboratory obtaining samples of highly toxic or contagious agents to use as a weapon. (aaas.org)
In addition, your veterinarian can obtain a diagnosis of ear mites by obtaining a sample from your kitten's ears and looking under a microscope using mineral oil as a base. (veterinarianelkinspark.com)
If needed, the student will also assist in obtaining samples for diagnostic tests, and will be involved in the discussion about how to best move forward with your pet's care. (vetmed.ucdavis.edu)