What chemical is unnecessary for conducting a Total Suspended Solids (TSS) test?

In the context of conducting a Total Suspended Solids (TSS) test, the focus is on measuring the concentration of suspended particles in water. The TSS test primarily involves filtering a sample through a specific size filter and then drying the filter to quantify the mass of the solids retained.

Sodium Thiosulfate, DPD, and Nitriver serve purposes related to other types of water quality tests, such as chlorine testing (Sodium Thiosulfate is used to neutralize chlorine), colorimetric analysis for various parameters (DPD is commonly used for measuring free and total chlorine), and nitrate testing (Nitriver). None of these chemicals plays a direct role in the process of measuring total suspended solids.

Therefore, since conducting a TSS test does not require any of these specific chemicals, it is accurate to state that nothing from the provided options is necessary to perform a TSS test, making the answer that nothing is required correct.