Method 375.4

Sulfate (Turbidimetric)

This method is for the determination of sulfate from drinking and surface waters, domestic and industrial wastes. An aliquot of sample is treated with barium chloride to form a barium sulfate suspension under controlled conditions.  The resulting turbidity is determined by a nephelometer, filter photometer or spectrophotometer and compared to a curve prepared from standard sulfate solutions. 

The method is suitable for all concentration ranges of sulfate; however, in order to obtain reliable readings, use a sample aliquot containing not more than 40 mg sulfate /L. The minimum detectable limit is approximately 1 mg/L sulfate. 

Suspended matter and color can interfere with the analysis. Correct by running blanks from which the barium chloride has been omitted. Silica in concentrations over 500 mg/L in the sample will interfere with the analysis.

(EPA: Office of Water)


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Method Data

Hold Times, Preservatives, Preps, Collection, Analytical & Documentation
Holding Time:   28 days from sample collection to analysis.
Preservatives:   Store samples at 4°C.
Required Preps:   Samples should be collected in plastic or glass bottles.
Collection Method:   Grab sampling
Analytical Methodology:   Spectrophotometer
Documentation:   375.4

Analyte List*

Analyte Formula CAS Number Detection Limit

* The analytes and detection limits listed for each method represent the typical detection limits and analytes reported for that particular method. Keep in mind that analyte lists may vary from laboratory to laboratory. Detection limits may also vary from lab to lab and are dependent upon the sample size, matrix, and any interferences that may be present in the sample.