Hi, I am just getting started with our Hamilton Star and fairly new to liquid handling in general.
My current workflow requires dispensing 4µl of critical reagent to each well of a 96-well plate. My first thought was to use a single channel with a 50µl tip and repeat dispense to a single row at a time. I could divide my reagent into 8x tubes and use all 8 channels to do the same for all 8 rows simultaneously. Is there a way to aspirate into all 8 channels from a single tube in series fashion?
I’d imagine this is not a unique or particularly challenging problem. How would you go about it? Thanks!
For your first approach, you can have an initial step that uses a high-volume tip to transfer the volume you need to a 12-column reservoir, then use the 8 channels from there so you don’t have to do individual aspirate steps if speed is valuable
For the second approach, there are probably more elegant/straightforward ways to do it but you might be able to do the following:
Create a sequence with your tube position repeated 8 times
Pick up tips
Aspirate from your synthetic duplicated sequence (set sequence counting to manually if you need several aspirate loops)
Dispense as required.
I haven’t used this before so your mileage may vary, but from a quick test on VENUS, it doesn’t error out in simulation. Unsure how it behaves physically though
So yeah I arrived at the 2nd approach pretty soon after posting and it worked in the simulator. I was initially overcomplicating things trying to use a loop variable on the channel selection which failed outright. The simulator shows the aspiration as a single step so I am a little concerned it is actually going to do the right thing, but I am planning to setup a water test shortly.
Depending on the reagent that you are looking to transfer, this may work but it unfortunately may also not work. Hamilton has an NGS assay ready workstation where this is always the first approach with delicate and expensive reagents like master mixes and enzymes. And similarly, transfer volumes can be anywhere from 1uL to 12uLs but the dead volume provided in the kit prohibits aliquoting the reagent off to 8 separate tubes (1 tube for each row basically).
It sounds wise to use just 8 tips and multi-dispense from a single tube that has been adjusted to be 8 sequence positions - VENUS will be able to aspirate from it just fine. And while each channel has to move out of the way of the next channel to aspirate from the same tube the time saved on the multi-dispense part is significant. But the issue that arises is that each previous channel to aspirate sits longer waiting for the entire aspirate step to complete before it can move on to dispense. The channels that sit the longest (channel 1 most likely) may have unreliable dispense volumes with the subsequent multi-dispense.
With the NGS assay ready workstation utilizing expensive kits and expensive reagents, it often becomes a better solution to just perform single dispenses. The time it takes to aliquot is then a significant cost, but it often proves to be less of a cost than poor dispensing leading to a failed assay and a wasted NGS kit.
Sometimes the multi-dispensing does work though, so what you are seeing work in simulation could be worth a shot.
It depends on the level of automation and flexibility you want. Off the top of my head, here’s what I would do:
Place 8 empty tubes on the deck.
Place the 96-well plate on the deck.
Place the tube containing the critical reagent on the deck.
Pick up a 1 mL tip, move to the critical reagent, pre-wet the tip 3 times, then aspirate approximately 550 µL of critical reagent (using Surface Empty). [1mm below surface]
Dispense 65 µL into each of the 8 tubes (using Surface Empty, 0.5 mm from the bottom).
Your 8 tubes containing the critical reagent are now ready.
Pick up 50 µL tips on your 8-channels.
Aspirate 50 µL into each tip (pre-wet 3 times, surface part, before aspiration).
If drippy stuff, use anti droplet control. (If glycerol, you should be ok).
Dispense 1 µL back into the source tube (the first dispense is often less accurate). Alternatively, you can use larger-volume tips if you want to dispense a larger priming volume.
Perform consecutive dispenses into all wells (12 × 4 µL) using Surface Part .
Dispense any remaining reagent back into the corresponding critical tubes.
That only works if you have a full 96-well plate. If I had a partial 96-well plate, I would add a user prompt asking for the number of wells and stop the sequence accordingly.
If you’re cherry-picking, I would use the 96-well plate editor instead.
Additionally, if you are working in a regulated environment where precision and accuracy matter, you should create a custom liquid class for your reagent.
This process involves gravimetry. You can do it manually, but if you plan to perform it frequently, the Hamilton LVK is the way to go ($21K USD, worth every penny).
Its nice to know I can load each channel sequentially but between the sequential wait time error and multidispense error factors, I think Matt is right that single dispense would be the better solution.
If we end up needing to scale much beyond 2-4 plates at a time then it would be a reasonable choice to split the reagent up into 8 tubes as Kevin suggests.
