Define Sample Titration for Estimation of Vitamin c in Lemon Juice?

Cut the lemon into two halves with a stainless steel knife. Remove the seeds. Squeeze the juice from half a lemon, directly into a 25ml measuring cylinder containing exactly 10 ml of 6% metaphosphoric acid. Note down the exact volume of acid plus lemon juice. Transfer the contents of the measuring cylinder into a 100 ml volumetric flask, using 3% metaphosphoric acid for rinsing & transferring  Mix. If the solution is not clear, filter the solution through a dry filter paper into a dry flask. Pipette 10 ml of the filtrate into a 100 ml conical flask. Titrate against the dye solution till a light pink color appears which persists for 30 seconds. Calculate the content of ascorbic acid in the lemon juice.