Removing inherent biomarker sensor signals from the actual sensor readings

Question

[bluecipher]

I have two types of biomarker data:

1. raw data: these are the sensors scan readings.
2. background data: The background data was captured without any electrolyte or biomarker to isolate the sensor's inherent signals.

I need to remove background data from raw data. But when I do this, I get negative values because there’s no perfect alignment between the background and the scans. Due to the nature of the measurement process, there’s some drift between when the background is measured and when each scan is measured. How can I solve the drift/alignment problem to get good background subtraction? Thank you.