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SDCK LAB/Nitrate, Hach TNT 835 Standard Operating Procedure LR (0.23–13.50 mg/L NO3––N) Dimethylphenol Method - Method 10206 Nitrate (NO3-) is a natural and anthropogenic component of surface waters. It is a plant nutrient, and its presence can affect vegetation growth and thus affect aquatic habitats. Color or turbidity in samples can cause high results. Filtering of the sample eliminates color interference and a sample blank is not required. Perform this test at the recommended temperature to avoid an incorrect result. The recommended sample and reagent temperature is 20–23 °C (68–73.4 °F). Recommended reagent storage is 15–25 °C (59–77 °F). Filter samples as soon as possible to prevent bacterial degradation of the nitrate. If immediate analysis is not possible, store at 4 °C (39 °F) or lower if the sample is to be analyzed within 24 to 48 hours. Refer to data sheet to track progress throughout the procedure. Check boxes and record times and temperatures. Record any and all results, and make note of results that read under the detection limits or seem unusual. Change pipette tips between samples to avoid cross contamination. Label enough TNT test vials for each sample, and for duplicates and blanks Remember to process one sub-watershed batch at a time up to step 4 1 SDCK / Nitrate Standard Operating Procedure / revision 4/27/10
