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a' v k _ ..� PHOSPHORUS, REACTIVE APPENDIX Lf LowRange:0-2 Mg/L Page 1 0 Ascorbic Acid Method' Using PhoeVer 3 Phosphate Reagent For Water,Wastewater and Sea Meter Introduction This method has been approved by tate USE..PA for NPDES reporting purposes. i Phosphates commonly are grouped into three types: orthaphosphate,condensed(pyro,meta or other poly) phosphate and organically bound phosphate.The orthophosphate is the only reactive form determined directly, The other types require pretreatment for conversion to orthophosphate for analysis.In the Molybdovanadate Method,orthophosphate reacts with molybdate in an acid medium toproduce a phosphomolybdate complex.In the presence of vanadium,Ye:low vanadomolybdophosphoric acid is formed.The intensity of the yellow calor is proportional to the phosphate concentration.The procedure is applicable for water and wastewater analysis. The Molybdovanadate Reagent combines all the necessary ingredients in a single solution. Validate results by using Voluenea Analytical Standards and following the standard additions method e as out- lined in the Accuracy Check.Additional information on phosphate analysis may be found in th for Phosphorus,Reactive(Amino Acid Method). Introduction WARNING Some ofthe chemicals used in this procedure may be hazardous to the health and safety of the user if inappropriatelyhandled oraccidentally misused.Pleasereadall warnh7gson the reagent labels and read the safety section of this manual.Hazardous substances appear in italic type- face when they are used in the lest and deserve extra carr in handling.Itis al waysgood practice to wear safety glasses when handling chemicals. Wash thoroughly if any contact occurs. Follow instructions carefully. Sampling and Storage Collect samples in clean plastic or glass bottles that have been cleaned with 1:1 HydrochloricAcid Solution and rinsed with distilled or demineralized water.Do not use a commercial detergent because tie phosphate content may contaminate the sample.If samples cannot be analyzed the same day,add 2 0 reel.of Sulfuric Acid,ACS, for each liter or quart of sample,using a glass serological pipet and pipet filler.Mix.Check the sample pH with pH paper to be sure the pH is 2 or less.Add more acid if necessary.Store the sample at 4°C(34°F)or below. Samples perserved in this manner can be stored at least 24 hours.For longer storage periods,add 4.0 ml_of Mercuric Chloride Solution for each liter or quart of sample taken and mix.Use ormercuric chloride is discour- aged to minimize the amount of mercury released to the environment.Sample refrigeration is still required. Samples preserved with mercuric chloride must be spiked with a sodium chloride s^,andard solution to bring the sodium chloride level to 50 mg/L or mane if the sample is low in chloride.The addition of chloride prevents x mercury interference in the test. pH Adjustment Adjust the acidified sample to about pH 7 just before manning the test by adding Sodium Hydrvoxide Standard So- lution,5N, and mixing thoroughly.Want to room temperature before analyzing.When significant amounts of perservative are used,a volume correction should be made for the extra acid and base_by --..--.--ume(sample+acid+base)by the umpte voltirtte rind multiplying the result times the final test reading. t� �AEq�!tram S+rodrd il4riho�ear qac fanmidrion d rVurr wi!M'uarrwer - .