I’m running into an issue with my Echo 650 where DMSO is spilling when transferring from a 384 PP source plate to a 384 LDV destination plate. I’m transferring 9000 nL (2.5 nL droplets) per well, which is under the rated max volume for the LDV plate (~12 µL).
The thing is, I don’t see this problem when transferring directly from PP to a standard 384 assay plate at comparable volumes. It only happens when the LDV plate is the destination.
I’m using the LDV as an intermediate plate for serial dilutions — the low dead volume makes it ideal so I’m not wasting compound. But I can’t get the volume in there cleanly via acoustic transfer.
A few details:
Echo 650
Source: 384 PP, 100% DMSO
Destination: 384 LDV
Transfer volume: 9000 nL per well
Fluid class: DMSO
My suspicion is that the practical max destination volume for DMSO in the narrow LDV wells is lower than the rated spec due to DMSO’s lower surface tension, but I haven’t been able to find documentation on this.
Has anyone run into this? Is there a known max destination volume for DMSO specifically in LDV plates? Or is something else going on here?
Any suggestions for getting ~9 µL of DMSO into an LDV plate (acoustically or otherwise) would also be appreciated. Thanks!
9uL will be a super slow dispense via the Echo. What’s that take? Like 60mins per plate?
Such a large volume will be much more easily achieved with a disposable tip liquid handler. Bravo would be my choice, but Beckman, Tecan, Hamilton, anything really is going to be better than an Echo for this purpose. The downside is that you will need to use up disposable tips, unless you do it with a fixed tip Tecan 8 channels at a time.
For reference the highest volume we’d ever dispense on an Echo was 1uL. You could have better luck with doing this dispense in smaller increments on the Echo. I’m not positive that an Echo will be lowering the transducer to follow the source liquid level as it dispenses. With 9uL the liquid level is going to have a marked change and the transducer will need refocusing on the meniscus. To test that theory you could do nine 1uL dispenses and see if the DMSO is still seeping out of the destination plate.
Thank you so much. And yes it is about 10 minutes per plate. I am new to this, and the nine 1uL dispenses is a good test and I will try it today. We are also working on getting a Bravo up and running.
I think the Bravo is your ideal solution if you already have one. Even if it’s just a 96ST head you can still work with 384-well plates. And the Bravos will easily hit the small wells of a 384LDV plate. We used to use Bravos to dispense into 1536-well plates (with a bit of trouble).
Don’t forget to survey the destination plate between the transfers, to get the most diagnostic info. (Skip first couple of transfers, as thickness of the liquid column will not be sufficient for reliable results). Also, pay attention that the environment in which you are operating the plates is as dry as possible.
My suggestion for such a large volume is to use a Thermo Multidrop Combi nl reagent dispenser. It is very reliable and accurate and no need for disposable tips. Also, if your Echo is part of a Tempo platform, the integration of the Combi nl is rather straightforward and the device does not take up much space.
We have a few setups like this and to date we are very happy with the performance. Note that we only transfer DMSO with the Combi nl and usually for backfilling or to prepare the Fix plates. It saves a lot of time on the platform.
We are planning to use Combi nL with DMSO only, and I wanted to ask about maintenance.
From what I’ve read, the system needs to be cleaned at the end of each working day after finishing experiments for example by running a cleaning routine, priming, and emptying the tips with a solution. Could you please share how you usually handle the daily maintenance?
I would really appreciate hearing about your experience and any recommendations you might have.
Since the Combis we have with the Echos are exclusively used with DMSO and on a daily basis, sometimes overnight, we do not run a deep clean too often. What we do is a thorough priming before first use in a run.
In other projects where I’ve used it with other reagents, I was cleaning it daily with Micro 90 1% in MQ water ~25mL, then MQ water 25mL and finally 70% EtOH 25mL. You could simply prime those volumes or have a protocol that transfers that onto a low profile trough to collect the liquid. After that I primed with a dry bottle to flush all remaining EtOH out to get the tubes and leave it as dry as possible. To dispense the 25mL I put a 50mL Falcon inside the Combi nl tube, to reduce dead volume and so I only needed 1 Combi bottle.
There are some things here that don’t seem to add up. 9uL/well (3600 drop/ well, 3.5mL total for all 384 wells) will take on the order of 2.3 hours for a 650 to complete a plate (definitely not 10 minutes). Did you mean to say 900nL/well? 900nL should take about 15 minutes with the 650.
Also, the 14uL is the max volume for the Echo to dispense from a 384 LDV plate. There is not a spec for what volume it can hold when inverted as a destination plate. There is a threshold where fluids can drip from an inverted destination plate depending on fluid properties and surface area of the plastic. Surfactants will lower the dripping threshold. You can do an empirical test for that dripping threshold. Simply run a gradient of increasing volume across the plate. Invert the plate over a Kimwipe and stay below the volume for the destination wells where you see dripping.