Sulfate is present at widely varying concentrations in natural waters. It causes off odor and taste in drinking water. Sulfate levels are also measured in the beverage industry due to its effect on odor and taste. Sulfate levels must be monitored in cooling water and ion exchange systems in order to prevent calcium sulfate scale formation. The Sulfate Vacu-vials® test method employs the turbidimetric method. Sulfate ion reacts with barium chloride in an acidic solution to form a suspension of barium sulfate crystals of uniform size. The resulting turbidity is proportional to the sulfate concentration of the sample. Results are expressed as ppm (mg/L) SO4. Vacu-vials Kits require the use of the W1700 Photometer or a spectrophotometer capable of accepting a 13 mm diameter round cell. Instrument sold separately.