I’m confused by the following statement in the literature:
‘To use standard solutions more efficiently, pour the solution into a small bottle for every use. Tighten the calibration cap after use and do not pour any used solution back into the original bottle. Replace the calibration buffer solution in the small bottle after 10-15 times of uses.’
If I shouldn’t pour the solution used back into the original bottle, how can I use it 10-15 times??
Not sure what your confusion is. Use the fluid you put in the small bottle 10-15 times then discard it. Refill the small bottle from the larger bottle, either the one provided or a replacement bottle of solution (which you of course will inevitably need to purchase). Don't pour used solution from the small bottle into the larger one.