The Drug Testing Lab follows on finding both Greenhouse Control Room code locations in Resident Evil 2.
There you'll have to solve the Dispersal Capsule puzzle, and also pick up a new key item - the Signal Modulator.
Looking for something else? Visit our Resident Evil 2 walkthrough for more help.
Dispersal Capsule puzzle solution in the Drug Testing Lab
To reach the puzzle, first find the Greenhouse Control Room code locations then head from into the Greenhouse, go left then left again. Get the Herbicide Synthesis File from the table, and approach the workshop in the corner.
The aim is to create the exact amount of solution for the capsule, indicated by the red line.
There are three tubes - small, medium and large - and three buttons to control them. The left-most button moves the contents of the middle tube into the left one, while the middle and right buttons allow you to rotate the tubes round.
To solve the dispersal capsule puzzle, first combine the two halves so all of the solution is in one tall tube on the left:
Swap the two columns round and move the contents of the large tube into the medium one on the left.
Rotate the tubes so they go from small to medium to large, and move solution from the medium to the large, so all three tubes have solution in descending order.
Now rotate the tubes so the large tube (but the one with the least solution) and the small tube (the one with the most solution) are on the left and middle respectively.
Combine the two to move the solution up to the red line.
Completing this gives you the Dispersal Cartridge (Solution). As per the note, we're not done yet - you need to cool it next.
How to use the Signal Modulator and cool the Dispersal Capsule
Head back down to B1 via the Greenhouse, and head to the Lounge. Clear any enemies in the way, and investigate the Signal Modulator in your inventory. It needs to be tuned to the same signal as on the wall, MURF.
Use the shoulder buttons to move it to MURF, and change the dials to Green 2 O'Clock and Red 4 O'Clock.
Insert it into the wall to power up this area. Head north to the Server Room, which acts as a safe room - use the Typewriter and Item Box if you need it.
When ready, go south of B1 to the Low-Temp Testing Lab. There is a PC on the south side you can interact with for the Wayne Li's Inbox File. Enter the Low-Temp Testing Lab and insert the pesticide into the machine to cool it down.
Now make your way back to the Greenhouse Control Room - you may encounter more of those ivy zombies along the way - and enter the cooled pesticide into the machine so you can access the west side of the Greenhouse and get the Senior Staff wristband upgrade.
Combine it with your ID Wristband, and now you can access the West Area of the Laboratory.
Of course, things aren't that simple. As soon as you get it, Mr X will smash through the glass behind you. Sprint out of there and back to the Lobby - being sure to check out the computer in the Presentation Room you can now access for the Bryon Cartwright's Inbox File - and you should get away without fighting him.
Playing the DLC? Check out our list of Ghost Survivors Mr Raccoon locations. Elsewhere, our full Resident Evil 2 walkthrough explains every aspect's of Leon and Claire's campaigns, including C4 Detonator and Battery locations, Heart Key location, how to stop Mr X, the Clock Tower puzzle, Sherry block puzzle in the Orphanage, the Power Panel Parts puzzle solution, how to escape the Incinerator and the Chess Plug puzzle solution. Not only that, we also provide all Locker Code solutions, the Leon Desk puzzle solution, all Resident Evil 2 Safe Codes and Portable Safe solutions and the Hiding Place locations.
You're done with the East Wing for now - time to head back to the Main Shaft. Before you go to the West Area, now you have the Signal Modulator, you can access the panel in the Nap Room in the North Area.
Tune it to MUF first (Red at 4 O'Clock, and Green at 6 O'Clock) to get the Hip Pouch upgrade (the last of the game) as well as the Wayne Li's Note file.
It's time to wrap things up. When you're ready, head to the West Area, where you'll face the G Tyrant Stage 3.