Why do we have to reject first 10 ml after filtration?

The first 10 mL of filtrate is often rejected during filtration to ensure that any contaminants or impurities that may have been dislodged from the filter or residual material in the filtration apparatus are eliminated. This helps to improve the purity and accuracy of the collected sample. Additionally, it allows for the stabilization of the filtration system, ensuring that the subsequent collected filtrate is representative of the desired solution.