USDA-APHIS-WS-NWRC requires a Preliminary Analysis (5-batch) registration study (following EPA’s study guideline OPPTS 830.1700 [1]) to be completed on a manufacturing source of an active ingredient (sodium nitrite) in accordance with Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) Good Laboratory Practices (GLPs) [2]. This study must characterize the active ingredient, sodium nitrite, the major impurity in the sodium nitrite, sodium nitrate, and the impurity water in each of the 5 batches.