Wash them with water and dry them and weigh 100mg of leaf.
Chop and Grind it well using a matter and pestle.
Add 5ml acetone, since it is volatile in air, mix it fast and pour it back in the measuring thing.
Now we centirfuge it, while doing that remember to have another liquid with same measurment of liquid on the exact opposite side such that there's a balance. The density of acetone and water are quite similar so as far as density is concerned, we are good to go. Put the setting on 5000rpm for 5min. (In Lab its 100x rpm, so look for 50 rpm)
Fill the cuvette with 80% blank acetone solution. The volume of the cuvette is 4mL and it should be held on the transluscent sides. Conver the cuvette using the white top. Place it on the machine in such a way that the translucent side is facing us. Same process for the green sample.
Getting absorbance:
Make sure 100% mode (last button) is on and the reading is stable.
Click on the first button for getting absorbance, it should say 0.
Pull the black button until you here one click. You will get the reading.