Doing so will have significant computational overhead, you need to make sure you can do everything in time. You will have to go through the entire data multiple times, this is of the order O(n). Because you obviously can't do it without going through all data at least once and you need to do something with it too. Maybe you can save some time on automating send procedure - you can have a timer trigger interrupts regularly and then trigger transmission of the data with DMA. This will free up some computational power. If you need it that is, maybe you can handle it all the simpler way and still get it done. (you didn't even post MCU and frequency it operates on, as of writing this)
You can have either static or dynamic compression dictionary (what substitutes with what). If it's static, you can hardcode it on the receiving end to decompress. If it's dynamic, it will take more computation on MCU side to generate it and you will also need to transmit it as data to the receving side (PC), because it needs to decode it.
First, make a guesstimate on what kind of values your ADC returns more often. Maybe you'll want to compress most significant bits. You'll have to search for some specific algorithms, but I think there is no way to do it without giving up some bandwidth, because what you send needs to be distinguishable - are you sending actual raw data or compressed data or dictionary? For example, you can hardcode that every 16 bytes you will send a byte that will be a dictionary for the next 16 bytes (or more, but then your compression could get worse because of how various data is). Which means your compression needs to be good enough to overcome this overhead and still increase overall amount of data transmitted.
But step number 1 is always estimating if there is anything in the data to compress. If you expect all possible values to be totally random all the time, there is not much that you can do, you may want to discard some measurements then. This is simply your hardware limitation. You can only get so much with it.