What is the purpose of homogenizing a sample during COD analysis?

Homogenizing a sample during Chemical Oxygen Demand (COD) analysis is essential to create a uniform mixture. This uniformity ensures that the sample accurately represents the overall characteristics of the wastewater being tested. When a sample is homogenized, particles and components that may have settled or separated are evenly distributed throughout the mixture, eliminating localized variations that could lead to inconsistent or misleading results. A well-homogenized sample allows for reliable measurements of the COD, as it reflects the true concentration of organic pollutants across the entire sample rather than just a localized area.

In contrast, while initiating chemical reactions is important, homogenization itself doesn't trigger these reactions directly. Increasing the sample's volume or decreasing its pH are not objectives of homogenization in this context and do not contribute to the goal of obtaining accurate and representative analytical results.