SDCK LAB/Ammonia, Hach TNT 830 Standard Operating Procedure

ULR (0.015 to 2.000 mg/L NH3–N) Salicylate Method - Method 10205

Ammonia is a natural component of marine sediments and common constituent of municipal effluents and agricultural runoff. Ammonia may occur in concentrations that are toxic to marine organisms in toxicity tests; therefore, it must be accurately measured in order to rule out interference with toxicity test results.

Color or turbidity in samples can cause high results. Filtering of the sample eliminates color interference and a sample blank is not required.Recommended sample and reagent temperature is 20–23 °C (68–73.4 °F). Incorrect results may be obtained if test is not performed at the recommended temperature.Recommended reagent storage is 2–8 °C (35.6–46.4 °F).If immediate analysis is not possible, store at 4 °C (39 °F) 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 result that read under the

detection limits (UR, Under Range) 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 5

1 SDCK / Ammonia Standard Operating Procedure / revision 4/27/10

SDCK LAB/Ammonia, Hach TNT 830 Standard Operating Procedure (continued)

Before performing Step 8 set up Sample ID

Select Instrument Setup Select Sample ID, and scroll for the site ID that matches the vial label If you perform step 8 at this point, select main menu after inserting vial

and the instrument will begin to conduct test Repeat so all result data is stored in the spectrophotometer and can be

accurately reviewed for QAQC

Important Note: An analyte concentration greatly in excess of the stated range will adversely affect color formation, resulting in a false reading within the method range. A blue color will form if NH4 is present.

Summary of methodAmmonium ions react at pH 12.6 with hypochlorite ions and salicylate ions in the presence of sodium nitroprusside as a catalyst to form indophenol. The amount of color formed is directly proportional to the ammonia nitrogen present in the sample. Test results are measured at 690 nm. Refer to the current MSDS and SDCK LAB SOP- HAZ WASTE for safe handling and disposal instructions.

2 SDCK / Ammonia Standard Operating Procedure / revision 4/27/10