GE Analytical Instruments ©2006 11-2 DLM 14291 Rev. A
• A small ring stand and clamps will be required to support the glass purge
vessel.
• Two, 3-finger clamps work well for holding the purge vessel and gas bubbler.
• Volumetric flasks (10 mL) and pipettes (100 and 1000 µL) are useful for
preparing the standards and reagents.
• Syringes are required for injecting the samples into the purge vessel. Microliter
syringes (10 µL, 25 µL, 100 µL) with beveled needles are particularly useful.
• Gas-tight syringes are required for headspace analysis. Recommended sizes for
gas-tight syringes are 125 µL, 1 mL and 5 mL.
Circulating Water Bath for Nitrate Reduction –A circulating water bath capable of
delivering >90°C water is required. Cooling water (<15 °C) is also required. At
some locations, tap water can be used as the cooling water. At other locations, a
second circulating water bath or ice bath and peristaltic pump is needed if the tap
water is not cold.
Setup of Purge Vessel
The Purge Vessel consists of five components:
• Gas inlet line (ASM 00430)
• Purge vessel with heating jacket and condenser (ASM 03292)
• NaOH gas bubbler trap with Teflon sleeve (ASM 04000)
• Connection tubing from the purge vessel to the gas bubbler (ASM 00440)
• Outlet tubing with IFD filter (ASM 00450)
There are two different configurations of the purge vessel depending on whether
measuring nitrite only, using iodide and acetic acid, or measuring nitrate and
nitrite, using vanadium (III) and hydrochloric acid. Acetic acid is less corrosive than
hydrochloric acid and, therefore, it is not necessary to use the gas bubbler/NaOH
trap when measuring nitrite. The gas bubbler/NaOH trap must be used for nitrate
measurement. Nitrite reduction is performed at room temperature and a
circulating water bath is not required. Nitrate reduction is performed at> 90° C
and requires a circulating water bath and cold water for the condenser.
• Support the purge vessel on a ring stand using a three-finger jaw clamp to
secure the middle of the purge vessel. The side of the clamp with a single
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