What would cause incorrect results when testing for Sulfate with SulfaVer® 4?
Sulfate reagent variation
The Hach SulfaVer® 4 method is a turbidimetric method. The instrument is reading absorbance caused by the cloudiness or turbidity that forms in the sample after the reagent is added. There can be considerable variation between lots so a new calibration curve should be run for each new lot of reagents. A reagent blank is also recommended for more accurate results. Follow the procedure using deionized water in place of the sample. Subtract the reagent blank value from standard and sample results or perform a blank adjust.