Method 375.4

Sulfate (Turbidimetric)

This method is applicable to drinking and surface waters, domestic and industrial wastes. 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. Sulfate ion is converted to 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. Suspended matter and color interfere. Correct by running blanks from which the barium chloride has been omitted. Silica in concentrations over 500 mg/L will interfere.

Method Data

Hold Times, Preservatives, Preps, Collection, Analytical & Documentation
Holding Time:	None noted in method.
Preservatives:	Preserve by refrigeration at 4°C.
Required Preps:	Samples should be collected in plastic or glass bottles.
Collection Method:	Grab sampling
Analytical Methodology:	Spectrophotometer
Documentation:	375.4

* 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.