SEAL AQ400 Discrete Analyzer

The Large Lakes Observatory at the University of Minnesota Duluth operates a Seal Analytical AQ400 discrete analyzer that can be used for a broad range of analytical chemical procedures.  

 

http://www.seal-analytical.com/Products/DiscreteAnalyzers/AQ400DiscreteAnalyzer/tabid/806/language/en-US/Default.aspx 



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At present, the analytical services we offer are given below.  

 

SEAL AQ400 Method

Equivalent EPA/Standard Methods  

Range, Detection Limit

Internal sales (any U of M account)

External sales

(other accounts)

Ammonia (103A)1

USEPA 350.1 Rev 2.0  

Range = 0.02-2.0 mg N/L, 

MDL = 0.004 mgN/L

$4.76/sample

$7.85/sample

Nitrate/nitrite (127A)2

USEPA 353.2 Rev 2.0

Range = 0.012-2.0 mg N/L

MDL = 0.003 mg N/L 

$4.26/sample

$7.03/sample

o-Phosphate (SRP) (155A)3

USEPA 365.1 Rev 2.0

Range = 0.003-0.3 mg P/L

MDL = 0.0006 mg P/L

$4.05/sample

$6.68/sample

Total Phosphorus (TDP, TP, PP) (119A)4

USEPA 365.1 Rev 2.0

Range = 0.01-1.0 mg P/L

MDL = 0.003mg P/L

$4.05/sample

$6.68/sample

Silica (122A)5

USEPA 370.1 Rev 2.0

Range = 0.1-10.0 mg Silica/L

MDL = 0.018mg Silica/L

$4.75/sample

$7.84/sample

Sulfate (165A)6  

SM 4500-SO42- E

Range = 5.0-40 mg SO4/L

MDL = 0.09 mg SO4/L

TBD

TBD

Sulfide (635A)7

Spectrophotometric Determination of Sulfide, HMSO.

Range = 0.03-1.0 mg S2-/L

MDL = 0.004 mg S2-/L

TBD

TBD

 

1Ammonia: 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.

2Nitrate/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.

3Phosphate, 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.

4Phosphorus, 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. 

5Silica (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.

6Sulfate: 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.

7Sulfide: 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.