LaMotte SMART 3 Electronic Soil Lab - Manual (Page 86)

86 SMART3 Soil 1.11
RANGE: 0.00 - 15.00 ppm Zinc
METHOD: Zinc forms a blue colored complex with Zincon in a
solution buffered at pH 9.0. Other heavy metals are
complexed by cyanide and the zinc cyanide complex
is released by the addition of formaldehyde before
the other metal cyanide complexes are destroyed.
Sodium ascorbate is added to reduce the interference
of manganese.
INTERFERENCES: The following ions interfere in concentrations in soil
extract 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
Test P
rocedures