Phosphate Testing Protocol

SDCK LAB/Total Phosphorous, Hach TNT 843 Standard Operating Procedure LR (0.051.50 mg/L PO4P) Ascorbic Acid Method - Method 10210 Phosphate (PO43-) 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. The digestion in the total phosphate procedure usually destroys all color and turbidity and a sample blank is not required. Recommended sample and reagent temperature is 1525 C (5977 F). Recommended reagent storage temperature is 1525 C (5977 F). 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

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SDCK LAB/Total Phosphorous Hach Method 10210 Total TNT 843 SOP (Continued)

Do not perform step 5 until all samples have been added to vials,keep aside and put ALL samples into the reactor at same time. Remember to process one sub-watershed batch at a time after digestion (step 8)

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SDCK LAB/Total Phosphorous Hach Method 10210 Total TNT 843 SOP (Continued) Before performing Step 13 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 13 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 be accurately reviewed for QAQC

Summary of method Phosphates present in organic and condensed inorganic forms (meta-, pyro- or other polyphosphates) are first converted to reactive orthophosphate in the total phosphorus procedure. Treatment of the sample with acid and heat provides the conditions for hydrolysis of the condensed inorganic forms. Organic phosphates are also converted to orthophosphates in the total phosphorus procedure by heating with acid and persulfate. The reactive phosphorus procedure measures only the reactive (ortho) phosphorus present in the sample. The reactive or orthophosphate ions react with molybdate and antimony ions in an acidic solution to form an antimonyl phosphomolybdate complex, which is reduced by ascorbic acid to phosphomolybdenum blue. Test results are measured at 890 nm. The final samples will contain molybdenum. In addition, the final samples will have a pH less than 2 and are considered corrosive (D002) by the Federal RCRA. Refer to the current MSDS and SDCK LAB SOP- HAZ WASTE for safe handling and disposal instructions.

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