LaMotte DCL-20 Colorimeter - Manual (Page 29)

ZINC TEST
ZINCON METHOD
QUANTITY CONTENTS CODE
30 mL *Zinc Indicator Solution *6314-G
120 mL *Methyl Alcohol *6319-J
10 g Sodium Ascorbate 6316-D
25 g *Zinc Buffer Powder *6315-G
15 mL *Sodium Cyanide, 10% *6565-E
30 mL *Formaldehyde Solution, 37% *5128-G
1 “Diluted Zinc Indicator Solution”, Bottle,
w/1 mL pipet assembly
0128-MT
1 Graduate Cylinder, 10 mL, glass 0416
1 Spoon, 0.5 g 0698
2 Pipets, dropping, plastic 0352
1 Spoon, 0.1 g 0699
*WARNING: Reagents marked with a * are considered hazardous substances. Material Safety Data Sheets (MSDS) are
supplied for these reagents. For your safety read label and accompanying MSDS before using.
The availability of zinc in soils decreases with an increase in soil ph. Some soils that are limited above pH 6.0 may show a
zinc deficiency especially in well drained sandy soils. A nutrient interaction exists between soils that have a high
phosphorous level and show a zinc deficiency even though zinc levels were sufficient. This interaction is due to the
preferential uptake of phosphorus instead of zinc and the possible formation of insoluble zinc phosphates. Once zinc is
applied to the soil, it is relatively immobile because it is readily absorbed by organic matter in the soil.
Zinc is essential in promoting certain enzyme reactions in the soil and is required for the production of chlorophyll and the
formation of carbohydrates in plants.
AP PLI CA TION: Drinking and sur face wa ters, do mes tic and in dus trial waste wa ter.
RANGE: 0.01 - 3.0 ppm
METHOD: Zinc forms a blue col ored com plex with Zincon in a so lu tion buf fered at pH 9.0. Other heavy met -
als are complexed by cy a nide and the zinc cy a nide com plex is re leased by the ad di tion of
form al de hyde be fore the other metal cy a nide com plexes are de stroyed. So dium ascorbate is added
to re duce the in ter fer ence of man ga nese.
SAM PLE
HAN DLING &
PRES ER VA TION:
Sam ple should be an a lyzed within 6 hours af ter col lec tion. The ad di tion of HCl will help pre serve
the metal ion con tent, how ever the acid should be neu tral ized be fore anal y sis.
IN TER FER ENCES: The fol low ing ions in ter fere in con cen tra tions greater than those listed.
ION MG/L ION MG/L
Cd(II) 1 Cr(III) 10
Al (III) 5 Ni(II) 20
Mn (II) 5 Cn (II) 30
Fe (III) 7 Co (II) 30
Fe (II) 9 CrO4(II) 50
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1985-01 • 10/01