GE MOA 280i, Руководство по эксплуатации и обслуживанию

Страница: 126 / 211

GE Analytical Instruments ©2006
12-2
DLM 14291 Rev. A
performed at room temperature, and it is not necessary to connect a circulation
water bath or cold water supply to the purge vessel.
Preparation of the Nitrite Reducing Agent
To minimize reaction of the reducing agent with atmospheric oxygen, it is best to
prepare the reagent directly in the purge vessel. To prepare the reagent:
•
Close the drain stopcock, gas inlet stopcock and outlet stopcock on the purge
vessel and remove the septum and cap from the top of the purge vessel. Screw
the needle valve on the purge vessel all the way into the glassware to stop the
gas flow.
•
Add 4 – 6 mL of glacial or concentrated acetic acid to the purge vessel. This
volume should be sufficient to fill the first bulb of the purge vessel. Do not
replace the septum and cap at this time. The volume of the purge vessels will
vary and it may be necessary to experiment to determine the best volume of
acid to use in the purge vessel.
•
Adjust the outlet pressure on the inert gas cylinder’s regulator to 1-2 psi.
•
With the needle valve on the purge vessel fully closed, open any shutoff valves
on the inert gas regulator, and open the gas inlet stopcock on the purge vessel.
•
Slowly open the needle valve on the purge vessel to allow gas to flow into the
acetic acid. A slow, gentle bubbling of gas through the acid to remove any
dissolved oxygen is desired. Let the acid purge for a few minutes while
preparing the iodide solution.
•
Use a balance to weigh approximately 50 milligrams of NaI or KI. Accurate
weighing is not necessary since the requirement is an excess of the reagent and
the conversion efficiency is not affected by the iodide concentration.
•
Dissolve the iodide in 1-2 mL of deionized water.
•
Transfer the iodide solution to the purge vessel containing the acid and
continue to purge for a few minutes to aid in mixing the reagent.
•
Add 100 µL of the dilute antifoaming agent to the purge vessel.