Center for Freshwater Research and Education - CFRE

Calcium is analyzed using the SEAL AQ300 Discrete analyzer. ARSENAZO III specifically binds to calcium forming a blue-colored complex that can be

measured at 660/670 nm

References:

SEAL Analytical, AQ2 Method NO: UKAS-590-A

Tietz, NW., Fundamentals of Clinical Chemistry, 2nd Ed. (1976)

US Environmental Protection Agency, 40 CFR, Part 136, Appendix B

Chloride is analyzed using the SEAL AQ300 Discrete analyzer. The thiocyanate ion (SCN-) is liberated from mercuric thiocyanate through sequestration of mercury by the chloride ion to form non-ionized mercuric chloride. In the presence of ferric ions, the liberated thiocyanate ions form a highly-colored ferric thiocyanate. The absorbance of this complex is measured spectrophotometrically at 480nm.

References:

SEAL Analytical, AQ300 Method EPA-105-D Rev. A

Methods for Chemical Analysis of Waters and Wastes, US EPA 600/4-79-020, 1983: Method 325.2

Standards Methods for the Examination of Water and Wastewater, APHA/AWWA/WEF, method 4500-Cl-E (18th, 19th, 20th Ed.).

Color is analyzed using the SEAL AQ300 Discrete analyzer. Color is determined by comparison of the sample with known concentrations of platinum-cobalt standards. One unit of color is that produced by 1.0 mg/L platinum in the form of chloroplatinate ion. The absorbance of the solution is measured spectrophotometrically at 450 nm.

References:

SEAL Analytical, AQ2 Method EPA-147-A Rev. 0

Standard Methods for the Examination of Water and Wastewater, method 2120 B (18th, 19th, 20th ed.).

Standard Methods for the Examination of Water and Wastewater, method 2120 C (21th ed.).

U.S. Environmental Protection Agency, 40 CFR, Part 136, Appendix B and 136.3 Tables IB and II, and Part 143.

2003 NELAC Standard, National Environmental Laboratory Accreditation Conference, June 5, 2003, EPA-600/R-04/003, http://www.epa.gov/nerlesd1/land-sci/nelac/index.html

Manual for the Certification of Laboratories Analyzing Drinking Water, 4th ed., USEPA 815/B-97/001, March 1997.

Nitrate-N + Nitrite-N is analyzed using the SEAL AQ300 Discrete analyzer. The sample is mixed with pH buffer and then travels through a copperized cadmium coil, where nitrate is chemically reduced to nitrite. The chemically-reduced sample is mixed with color reagent, prepared in dilute phosphoric acid. The nitrite from chemical reduction and the original nitrite react with sulfanilamide to form a diazonium compound. This species couples with N-(1-naphthyl)-ethylenediamine dihydrochloride to form a reddish-purple azo dye that is measured photometrically at 520nm.

References:

SEAL Analytical, AQ300 Method EPA-127-D Rev. A

Methods for Determination of Inorganic Substances in Environmental Samples, USEPA 600/R 93/100, August 1993: Method 353.2, Revision 2.0

Standard Methods for the Examination of Water and Wastewater, APHA/AWWA/WEF, method 4500-NO3–F (2000)

Silica is analyzed using the SEAL AQ300 Discrete analyzer. Under acidic conditions molybdate-reactive silica combines with ammonium molybdate to form a yellow molybdo-silicic acid complex. This complex is chemically reduced by adding buffered 4-amino-3-hydroxy-1-naphthalenesulfonic acid to form a silico-molybdenum blue complex. The absorbance of the final product is measured spectrophotometrically at 660nm.

References:

SEAL Analytical, AQ300 Method EPA-121-D Rev. A

Methods for Chemical Analysis of Waters and Wastes, US EPA 600/4-79-020, 1983: Method 370.1

Standards Methods for the Examination of Water and Wastewater, APHA/AWWA/WEF, method 4500 SiO2 –C (20th Ed), and 4500 – SiO2 (18th, 19th Ed).

Soluble Reactive phosphate is analyzed using the SEAL AQ300 Discrete analyzer. Reaction with acidic molybdate in the presence of antimony forms an antimony phospho-molybdate complex. This complex is chemically reduced by ascorbic acid to an intensely blue complex: phosphomolybdenum blue. The absorbance of this complex is measured photometrically at 880nm.

References:

SEAL Analytical, AQ300 Method EPA-155-D Rev. 0

Methods for the Determination of Inorganic Substances in Environmental Samples, USEPA 600/R 93/100, August 1993: Method 365.1, Rev. 2.0.

Standard Methods for the Examination of Water and Wastewater, APHA/AWWA/WEF, method 4500-P-F (1999 forward).

Sulfate is analyzed using the SEAL AQ300 Discrete analyzer. Sulfate ion is converted to a barium suspension under controlled conditions. The resulting turbidity is determined using a filter photometer at 405 nm.

References:

SEAL Analytical, AQ300 Method EPA-165-D Rev. A

ASTM D516-11, Standard Test Methods for Sulfate Ion in Water, ASTM International, West Conshohocken, PA, 2011, www.astm.org.

Standard Methods for the Examination of Water and Wastewater, APHA/AWWA/WEF, 4500-SO42- E (1997 forward).

ISO/DIS 15923-1, Water Quality – Determination of selected parameters by a discrete analysis system – Part 1: Ammonium, nitrate, nitrite, chloride, orthophosphate, sulfate and silicate with photometric detection.

Total nitrogen converts organic and inorganic nitrogen to Nirate + Nitrite compounds by a high pressure digest. A potassium persulfate digestion is used to oxidize organic N and ammonia into nitrate. After digestions, Total nitrogen is analyzed using the Nitrate-N + Nitrite-N AQ300 discrete analyzer method.

References:

Ameel, J.J., R.P. Axler, C.J. Owen. 1993. Persulfate digestion for determination of total nitrogen and phosphorus in low nutrient water.  American Environmental Laboratory. 5: 2-11.

SEAL Analytical, AQ300 Method EPA-127-D Rev. A

Total phosphorus converts organic and inorganic phosphorus to soluble phosphorus compounds using a potassium persulfate digestion. After digestions, Total phosphorus is analyzed using the p-Phosphate-P AQ300 discrete analyzer method.

References:

Ameel, J.J., R.P. Axler, C.J. Owen. 1993. Persulfate digestion for determination of total nitrogen and phosphorus in low nutrient water.  American Environmental Laboratory. 5: 2-11.

Methods for the Determination of Inorganic Substances in Environmental Samples, USEPA 600/R 93/100, August 1993: Method 365.1, Rev. 2.0.

Standard Methods for the Examination of Water and Wastewater, APHA/AWWA/WEF, method 4500-P-F (1999 forward).