LaMotte Nitrate-Nitrogen Low Range Enzyme Kit - Manual (Page 8)

The reduction of nitrate to nitrite (reduction in oxidation number from +5 to +3
on the nitrogen by the addition of two electrons) occurs following the general
reaction
NADH + Nitrate à Nitrite + NAD
+
+ OH
_
with YNaR1 acting as the catalyst.
In effect, the electrons are transferred from the NADH to the nitrate molecule,
reducing the nitrate to nitrite.
1 Campbell ER, Kinnunen-Skidmore T, Winoweicki LA, Campbell WH. A new trend in nitrate
analysis: and enzyme-based field test for nitrate. AM LAB News 2001: 33 (4):90-2.
The Ni trate-Ni tro gen En zyme Re duc tion Kit
The Enzyme Vials contain both freeze-dried NADH and YNaR1. The nitrate
reduction takes place under buffered conditions at the molybdenum site on the
YNaR1 enzyme. The YNaR1 is first reduced by the NADH and then the nitrate
is reduced at the molybdenum site. The nitrite produced is then detected by
running the standard Griess reaction in acidic conditions with sulfanilamide and
N-1 indicator in tablet form to produce a red-violet colored complex that is
proportional to the concentration of nitrate.
Con ver sions
Nitrate test results are expressed as “nitrate-nitrogen” (NO
3
_ N), meaning
“nitrogen that is in the form of nitrate”. Some test kits express levels only as
nitrate (NO
3
). Both expressions refer to the same chemical but express the
concentration in different units of measure. To convert ppm nitrate-nitrogen to
ppm nitrate multiply by 4.4.
ppm Nitrate-nitrogen X 4.4 = ppm Nitrate
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PO Box 329 • Chestertown • Mary land • 21620
800-344-3100 • f 410-778-6394 • www.lamotte.com
68137 02.08