1. Locate the board shown in the image, this will indicate which pipe you'll be looking for. This is in the scientist's lab found on the first level after ziplining up using the boat entrance. The name of the sample is the one described as having the highest purity.

2. Locate the graph shown in the second image, this will indicate which colour pipe you'll be looking for. Found on the same level as the scientist's lab in the admin office. The colour of the sample is the colour of the line with the highest peak on the graph.

3. Use the name of the sample from the board and the colour from the graph to find the correct sample. The oil tanks can be found on the level above the lab and admin lab joined onto the break room.