Hach DR/850 - Page 427

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Interferences
Summary of Method
This test measures all hydroxylated aromatic compounds,
including tannin, lignin, phenol and cresol. This method produces
a blue color proportional to the amount of these compounds
present in the sample. Report results as total tannin and lignin
expressed as mg/L tannic acid.
REQUIRED REAGENTS
Cat. No.
Tannin and Lignin Reagent Set (up to 100 tests) ..........................................................22446-00
Includes: (2) 675-49, (1) 2560-42
Quantity Required
Description Per Test Unit Cat. No
Sodium Carbonate Solution ..................................... 10 mL................. 500 mL..............675-49
TanniVer 3 Tannin-Lignin Reagent .......................... 1 mL.................. 100 mL........... 2560-42
Water, deionized....................................................... 25 mL........................ 4 L..............272-56
REQUIRED APPARATUS
Pipet Filler, safety bulb .................................................1 ...........................each ..........14651-00
Pipet, volumetric, Class A, 5.0 mL...............................1 ...........................each..........14515-37
Pipet, volumetric, Class A, 0.5 mL...............................1 ...........................each..........14515-34
Sample Cell, 10-20-25-mL, w/ cap...............................2 .........................6/pkg ..........24019-06
OPTIONAL REAGENTS
Formaldehyde........................................................................................ 100 mL ............2059-32
Sodium Pyrophosphate, ACS......................................................................50 g ..........14295-25
Tannic Acid ...............................................................................................113 g..............791-14
Substance Interference Level and Treatment
Ferrous iron Causes a positive interference. Two mg/L of ferrous iron produces
a color equivalent to about 1 mg/L of tannic acid. To eliminate
interference of ferrous iron up to 20 mg/L, add one 0.2-g scoop of
sodium pyrophosphate to the sample before testing.
Sulfide Eliminated by adding 1 mL of formaldehyde to the sample before
testing the sample.
TANNIN AND LIGNIN, continued