HPLC Calibration

While HPLC Gradient Calibration- For LC2010 series- in A pump-100%water and in B pump- 3mL Acetone in 1L water used.
For LC2030 series 10 mg caffeine in 1L water used. My question is why different combinations are using? Can anyone explain…thanks in advance.

Actually Acetone Are in All Labs Bcoz Acetone Is Highly Absorbance and water Not have absorbance