LaMotte SMART Spectro Spectrophotometer - Manual (Page 209)

generally not more than 0.1 mg/L unless the water has become polluted from
wastewater sources or excessive drainage from agricultural areas.
APPLICATION: Boiler, cooling, and industrial water.
RANGE: 0.0–100.0 mg/L Total Phosphorus as phosphate
METHOD: Pretreatment of the sample with heat and acid provides
conditions for the hydrolysis of condensed inorganic
phosphates. Heat, acid and persulfate convert the organic
phosphates to orthophosphate during the digestion.
Orthophosphate reacts in acid conditions with ammonium
vanadomolybdate to form vanadomolybdophosphoric acid.
The resulting yellow color is proportional to the
concentration of orthophosphate.
SAMPLE
HANDLING AND
PRESERVATION: Rinse sample bottle with 1:1 hydrochloric acid followed by
deionized water. Do not use phosphate detergents. If the
sample can not be analyzed immediately, the sample should
be preserved by adjusting the pH to 2 or less with
concentrated sulfuric acid and refrigerated at 4°C. Warm the
sample to room temperature and neutralize with 5.0 N
sodium hydroxide before analyzing.
INTERFERENCES: Large amounts of turbidity may interfere. Silica and arsenate
interfere only if the sample is heated. Arsenite, fluoride,
thorium, bismuth, molybdate, thiosulfate, and thiocyanate
cause negative interference. Ferrous iron concentrations
above 100 ppm will interfere.
þNOTE: For greater accuracy, use laboratory grade pipets. To order reagent
refills, order code R-4025.
Phosphorus, Total HR 2/3 SMART SPECTRO TEST PROCEDURES 05.04