LaMotte SMART 3 Electronic Soil Lab - Manual (Page 75)

SMART3 Soil 1.11 75
NITRITE-NITROGEN
DIAZOTIZATION METHOD • CODE 3650-SC
QUANTITY CONTENTS CODE
2 x 60 mL *Mixed Acid Reagent *V-6278-H
5 g *Color Developing Reagent *V-6281-C
1 Spoon, 0.1 g, plastic 0699
1 Dispenser Cap 0692
*WARNING: Reagents marked with an * are considered to be potential health
hazards. To view or print a Material Safety Data Sheet (MSDS) for these reagents
go to www.lamotte.com. To obtain a printed copy, contact LaMotte by e-mail,
phone or fax.
Nitrites are formed as an intermediate step in the production of nitrate. Soils
that are well drained and aerated contain only small amounts of nitrite nitrogen.
Excessive nitrites, which are toxic to plants, may result from soil conditions
unfavorable to the formation of nitrate, such as inadequate aeration. High nitrite
readings may also be encountered in soils with large amounts of nitrates, where
a portion of the nitrate nitrogen decomposes to form nitrites.
APPLICATION: 0.00-40.00 lb/acre Nitrate-Nitrogen
METHOD: The diazonium compound formed by diazotization of
sulfanilamide by nitrite in water under acid conditions
is coupled with N-(1-naphthyl)-ethylenediamine
to produce a reddish-purple color which is read
colorimetrically.
INTERFERENCES: There are few known interferences of substances at
concentrations less than 1000 times that of nitrite;
however, the presence of strong oxidants or reductants
may readily affect the nitrite concentrations. High
alkalinity (above 600 mg/L) will give low results due to a
shift in pH.
Test P
rocedures