Hi,
I was just wondering about peoples experience and knowledge with liquid classes, specifically when one that exists can be used for other similar liquids and when a new one is needed.
An example of what i mean would be is are different classes necessary between say Human serum and cyno serum? and further to mouse serum? or serum and plasma?
Another example would be between say 2% BSA in PBS and 5% or 10% etc?
My final query is about the location when classing, in this case serum classes developed in Nevada is being used in the UK. Would we likely have to re class because of the environmental factors such as humidity or are this effect insignificant in volumes over 10 uL?
I know the obvious answer is to test it all myself but as liquid classing takes so long i was just curious to see what people thought before i poured hours into checking.
Thanks for any insight provided,
Ewan
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With large volume transfers, one liquid class is usually fine for something like 2, 5, 10% BSA in PBS. For example, I use the pre-programmed Glycerol liquid class with my mastermix that is only ~50% Glycerol and it works very well.
I don’t think you’ll need a new liquid class between serums unless you notice that they are considerably different from each other, but the only way to really know is to test it. There may be very small tweaks that you want to make for each serum type.
I do find that lower volumes (1-50ul) demand more tightly regulated liquid classes and this is where you will need to do some development work.
Using a defined liquid class in two different environments can be tricky depending on the building that the robot is house in. In Canada I have heard that some groups situated in older buildings use a different liquid class for winter and for summer (It’s extremely dry here in winter and very humid in the summer). My lab is in a newer building with proper enviromental controls. Our temperature is static and humidity stays at ~40% so I don’t have any issues when the seasons change.
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That’s great. Thanks Christina
Your questions are abswered easily, but the implications of the answers can get complex.
The percentages of whatever is in your liquids are irrelevant as long as they do not meaningfully change its physicsl properties. “Meaningful” in this regard means how many bubbles, standard deviations, etc. you are willing to accept.
In the same vein, environmental factors necessitate different liquid classes once they push your result into unacceptable territory. As an example, I know that some NGS protocols in Scandinavia run with Summer and Winter liquid classes because the difference in humidity is just that stark.
From a practical point: Always run a test method with the liquid and the liquid class you want to pair and see whether the results are okay. If not, start development.
Even more practical: Serum/plasma of different species is almost never meaningfully different. There is also no meaningful difference to the different BSA percentages that are used in PBS in normal laboratories. Once you get to non-pyhsiologically relevant levels you have to start liquid class development. Generally speaking, the standard liquid classes are fine for 80-90% of applications, which are about high throughput and documentsation, not pinpoint precision.
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Thank you for such a detailed answer.
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