Hello comrades!
Colud you please share your experiance at checking dispernsing volume? How do you do it? What devices do you use or methods? At my job we have Echo that we can check volume beatwen 2-60 uL, and also VolumeCheck for larger volumes, but I’m just wondering about other options.
Thanks!
I recommend checking out the ISO 23783 documents for guidance on volume checks. The ISO 23783 guidelines consist of three parts that are specific to automated liquid handling systems (ALHS):
The ISO 23783 Part 2 document is most pertinent to your questions as it applies to all ALHS accounting for a wide variety of technologies and tests that can be performed to assess pipetting performance. There are a lot of approaches, each has its pros and cons, sensitivities, volume ranges, etc.
At Hamilton, we employ several of these measurement methods depending on the pipetting technology and needs.
The VeriPlate is something new we showcased at SLAS that will launch soon and is part of our larger Hamilton Pipetting Excellence initiative. This link will get you access to the whitepaper I recently co-authored with my colleagues. Also, see here for the Liquid Handling Reference guide that includes a section on measuring liquid transfers.
Liquid handling in general and verification of said liquid handling as it pertains to automation are topics that have been of great interest and even passion of mine throughout my career. In addition to the tools Hamilton provides, we also have active collaborations with vendors such as Artel so our customers have many options based on their specific needs. I am very eager to hear everyone’s thoughts in this thread!
Hi Eric,
Thanks for this wealth of information! When I go to download the white paper, however, I get a “404 not found” error. Is this on my end or are others experiencing this as well?
I see the issue - it was working before! I let the marketing and website team know and will update you when it’s been corrected.
UPDATE: It’s been fixed!
Thanks, Eric!
Volume verification has been a critical issue in our operations for decades. It’s great to see more solutions enter the marketplace to help us with quality of results.
In my view, volume verification is divided into two camps.
Reference methods deliver a static reading of liquid handler performance at a given point in time. You validate your liquid handler periodically and then proceed with your assays hoping that the performance level you measured previously remains fairly consistent. Examples of reference methods are the various dye-based routines and capillary measurements.
Real-time, in-line solutions measure your actual samples in the process microplate with your system fluids. These can be run on every plate in an assay and data recorded for each well in every plate, at every addition/aspiration if you desire. This results in actionable in-process data which can then be utilized to facilitate true ratiometric dilutions, flag liquid handler/device errors, audit incoming levels, and so on. Examples of in-line solutions are acoustic measurement, ultrasonic, conductive/capacitive pipet tip, pressure-based, and optical.
I’m working with Meniscense, https://www.meniscense.com/, who launched their VolumeSense production device at SLAS 2024. The VolumeSense uses optical interferometry to provide a high-resolution and non-contact means for volume measurement, in-line with your method.
We at Synthace use the Artel - they have verification for 96 and 384 well plates.
There are also many articles published from liquid handling manufacturers that use the Artel to prove their accuracy and precision specs.
But before we started using the Artel we did simple Tartrazine and plate reader readouts. Easy and cheap solution for measuring precision but not for accuracy.
Out of curiosity why are you using the echo for 60uL dispenses? That’s going to take a very long time…
My lab recently implemented routine gravimetric verifications using Matrix tubes and an XL20 to weigh individual tubes. We were getting accuracy and precision results <8% and <5% respectively until recently. Something has changed however and our results are deviating significantly from expected across several Hamilton STARs. We just received a new lot of tips and I’m wondering if that could be a factor. Has anyone else had precision and accuracy drops between tip lots? We are still on CO-RE I, but using CO-RE II tips.
This is greatly dependent on what you’re transferring, how you specifically test your accuracy and precision, if your XL20 is accurately weighing samples, etc. Have you tried testing the same samples with different lots and comparing your results?
I would recommend bumping our your topic to the Hamilton (Venus) category to get better visibility as those who work there are extremely responsive to this forum.
Our method is basically just weighing empty matrix tubes individually, then pipetting DI water directly into the tubes and reweighing them.
Initially we had some issues with the accuracy of the scale, but addressed those by warming up the instrument longer and adding a scale test prior to use.
Unfortunately I only have one lot of tips at the moment. I just ordered more to do a comparison.
I’ll reach out on the Venus form if I can’t get this sorted soon. 
Just a thought, have you taken into account lab humidity and temperature? That can affect your pipetting results.
In our testing of CORE II tips on CORE I hardware with Artel we didn’t notice a significant difference. It would be worth while to get another lot of tips to test.
The new shipment of tips worked perfectly, first try. (Still CORE II tips on a CORE I head) But it is the same lot and I am really reluctant to blame the tips at this point. I need to do further comparative testing to really say.
When I evaluated the lab humidity and temperature I did notice that it was different, especially compared to when the method was developed. But they humidity and temperature are not extreme. For example this is when the method was developed:
Do you think that’s enough of a difference to effect the accuracy?
We are also having an issue where one particular Hamilton will sometimes, once in every 160 tip pickups, fail to pick up the entire rack of 10ul tips with the CO-RE I head. I will randomly fail to pick up ~15-20 tips out of 96. Different tips each time. I’ve tried to recreate the failure and haven’t been able to. Everything is aligned and passing checks.
If you look at a particular day in April, it looks like your temperature range is tighter compared to August. (The graph temperature scale is different). Your humidity in April also looks tighter but swings down and up over the month.
From your data it looks like your average is about the same across months and considering a new shipment of tips but same lot did not cause issues then I don’t think the swing in temperature and humidity caused your routine gravimetric verification to fail.
From your comment about the tip pick up issue, I have seen a stuck up tip in the tip rack cause the CORE head to fail to pick up some of the tips in a random pattern. Typically it ends up in a crash or the CORE head ends up smashed tips. Also unlikely but the tip carrier insert with the two prongs is missing/not seated, or a tip rack not seated well will cause tip pick up issues with the CORE head.
For your routine gravimetric tests that failed, was it underdispensing? If it was it might be that the tip was picked up but wasn’t forming a good seal around the channel for whatever reason.
