The Large Lakes Observatory at the University of Minnesota Duluth operates a Seal Analytical AQ400 discrete analyzer and two Turner Designs Fluorometers that can be used for a broad range of analytical chemical procedures.
Below are a list of analyses prices as of October 2024.
Additional information and references
- Ammonia: Hypochlorite-phenol method equivalent to EPA 350.1 version 2 (1993) and Standard Methods 4500-NH3 G (19th and 20th). Freshwater only (not for brackish or saline water). Interferences include dissolved calcium and magnesium, sample turbidity and color.
- Ammonia: Holmes, R. M., et al. (1999) A simple and precise method for measuring ammonium in marine and freshwater ecosystems. Can. J. Fish. Aquat. Sci. 56: 1801-1808. Taylor, B. W., et al. (2007) Improving the fluorometric ammonium method: matrix effects, background fluorescence, and standard additions. J. N. Am. Benthol. Soc. 26(2):167-177.
- Chlorophyll-a: Welschmeyer, N. (1994) Fluorometric analysis of chlorophyll a in the presence of chlorophyll b and pheopigments. Limnol. Oceanogr. 39 (8):1985-1992
- Color: Color is determined by comparison of the sample with platinumcobalt standards. One unit of color is that produced by 1 mg/L platinum in the form of chloroplatinate ion. The absorbance of the solution is measures spectrophotometrically at 480nm.
- Nitrate/Nitrite: Cadmium column reduction to nitrite with reaction with phosphoric acid, sulfanilamide and N-(1-naphthylethylenediamine) dihydrochloride. Equivalent to EPA 353.2, version 2 and Standard Methods 4500-NO3 F (18th, 19th, and 20th). Interferences include chlorine, sodium thiosulfate, highly alkaline or overly acidified samples, iron, copper, other metals, oil and grease.
- Phosphate, Ortho: Acidic molybdate/antimony with ascorbic acid reduction (phosphomolybdenum blue). Equivalent to EPA 365.1, version 2 (1993) and Standard Methods 4500-P F (18th, 19th, and 20th). Interferences include bariuim, lead, silver, silica, nitrite, sulfide, arsenate, hexavalent chromium, and arsenic.
- Phosphorus, Total: Acidic molybdate/antimony with ascorbic acid reduction (Manual persulfate digestion required). Equivalent to EPA 365.1, version 2 (1993) and Standard Methods 4500-P B, F (18th, 19th, and 20th). Interferences include high iron, copper, and silica; nitrite, sulfide, arsenate, and hexavalent chromium.
- Silica (Reactive Silica): Acidic molydate with ANSA reduction (silico-molybdenum blue). Equivalent to Standard Methods 4500-SiO2 D (20th). Interferences include phosphorus and tannins, iron and sulfides.
- Sulfate: Barium chloride turbidimetric method with use of gelatin as suspension agent. Equivalent to ASTM D516-11. Interferences include high iron, copper, and silica; suspended materials, polyphosphates and phosphonates, very high chloride, aluminum, polymers, and large quantities of organic matter.
- Sulfide: Potassium dichromate converts DPD (N,N-Diethyl-p-phenylenediamine) to the free radical which reacts rapidly with sulfide to produce a blue color (Ethylene Blue) which can be measured photometrically at 660nm. Interferences include thiosulfates, sulfites and iodides, and zinc as zinc acetate.
Preservation
Samples should be preserved by freezing or with the addition of sulfuric acid.
To inquire about any services listed on this page, please contact Sandra Brovold ([email protected]). Turnaround times are variable. We will give you our best estimate at the time of the order.