Phosphorus is the 11th-most-abundant element in the earth’s crust and is an essential nutrient for all living organisms. Phosphorus exists in nature primarily as phosphates (PO4). Inorganic species include ortho, pyro, hypo and meta phosphates, which exist in minerals and are primarily used in fertilizer. Organic phosphates produced by biological processes are present in ATP, DNA, RNA and the phospholipids in every cell membrane. Phosphates primarily enter the water system through agricultural runoff and effluent from wastewater treatment plants. Excessive amounts of phosphorus in waterways can lead to algae blooms and eutrophication.
The Model CA6 total phosphorus analyzer is an easy-to-use online sequential sampling analyzer available in three ranges: 0 to 2.0 mg/L, 0 to 20.0 mg/L and 0 to 100 mg/L. The CA-6 is lightweight and easy to install, weighing less than 40 lb. It can be wall-mounted or simply set on a bench using the optional bench-top stand. After the sample, waste and reagent lines have been connected and the analyzer is provided with power, the CA6 is ready to begin its preprogrammed analysis sequence. The CA6 is a single-channel analyzer with a 4-20 mA output. It is available with up to four channels. A simple, user-friendly menu structure and touch-screen interface makes it easy to access information or customize analyses.
The analysis is a three-step process. First, the phosphorus compounds are oxidized to ortho-phosphate using sulfuric acid, sodium persulfate, UV radiation and heat. Second, sodium molybdate is added to form a phosphomolybdate compound, which is reduced in step 3 with sulfite to produce molybdenum blue. Photometric differential absorbance at 850 nm between the sample and the blue analyte uses the Beer-Lambert law to determine the total phosphate concentration. The CA6 is accurate, reliable and easy to use.
