Eicom ENO-30, User Manual

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6. Analysis
6-1. Accurate Analysis
NO
2
exists in the air and dissolves in water. NO
2
-
is gradually oxidized to NO
3
-
in the solution.
Because most of lab
s’ equipment is polluted with NO
2
-
and NO
3
-
, we have to pay careful
attention to removing contamination, especially for highly sensitive analysis. This pollution is
eliminated by a few rinses with non-polluted water (fresh super pure water). The microsyringe
and sample injector (manual and external) are easy to contaminate. It is sometimes difficult to
make the micro syringe clean. To make it clean, connect a microsyringe to an aspirator and
aspirate conc. HCl. Then rise with super pure water. The manual injector, and its injection port,
can be cleaned by super pure water flushed by a syringe with a port cleaner attachment. If this
flush does not resolve the contamination, disconnect the sample loop and wash the loop with
HCl and water. Super pure water is also the candidate of contamination removal. It is better not
to store the water; always use fresh super pure water. If storage is necessary, air tight bottle
made of glass is suitable for contamination prevention.
6-2. Water Quality
All water used for ENO-30 maintenance and sample preparation must be super pure water (18.2
Mega-Ohm x cm). Distilled or deionized water may be used, although this is not ideal for
ENO-
30 and accurate analysis. It’s best that the water come directly from the water purification
system tap. These water quality recommendations help prevent cross contamination of NO
2
-
and NO
3
-
and prolongs the life of the ENO-30.
6-3. Reagent Quality

Water; Fresh MilliQ water direct from tap od well maintained system or HPLC grade water.
Do not store the water in a plastic bottle. Please use a glass bottle.

Hydrochloric acid; Analysis or Super grade, 35-37% Hydrochloride.

Methanol; HPLC Grade

Standard, reagent grade