DISCRETE ANALYZER CHEMISTRY Sulfate (SO 4 -2 ) Method
Methods Referenced • EPA Method 375.4 — Sulfate, Turbidimetric • Standard Methods 4500-SO 4 -2 E — Turbidimetric Method • ASTM D516-11 — Standard Test Method for Sulfate Ion in Water • ISO 15923-1 — Water quality — Determination of selected parameters by discrete analysis systems — Part 1: Ammonium, nitrate, nitrite, chloride, orthophosphate, sulfate and silicate with photometric detection
Method Range 2.0 – 40 mg SO4/L Reagent Composition Only one reagent is used for the SO 4
-2 method. The SEALAnalyticalAQ Sulfate Rgt
is made in trace HCl and final concentrations are as follows:
SEALAnalyticalAQ Sulfate Rgt • 10 g/L Barium chloride dihydrate or 48 mmol Ba +2 • 20 g/L Sodium chloride • 0.5 g/L gelatin
Chemical Reactions Ba +2 + Free SO 4
-2 BaSO 4
Sulfate ion is converted to a barium suspension under controlled conditions. The resulting turbidity is determined photometrically and compared to a curve prepared from standard sulfate solutions.
Note: Calculations using the limiting factor of Ba +2 (by moles) show that this reagent can react with a maximum of ~4600 mg/L free sulfate. However, method range is much lower due to instrument limitations.
Note: We recommend utilizing ICSO41 to manufacture your standards and check solutions for this method. The SEAL method calls for a Sodium Sulfate starting material, though, we have not noticed any difficulties associated with using the Potassium Sulfate starting material.
For more information, contact EMAIL: inform@seal-us.com PHONE: (262) 241-7900 WEBSITE: seal-analytical.com
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