AZI Customer Service 800-528-7411 or 602-470-1414
Page 29 of 56
Potential Interferences
Potential interferences to the Jerome
®
mercury vapor analyzers are rare and most of these can be
eliminated with proper maintenance procedures. However, erroneously high readings can
sometimes occur. Here are a few things to be aware of when using the instrument:
The gold film sensors used in the Jerome
®
mercury vapor analyzers do not respond to the
following compounds:
•
Hydrocarbons
•
CO, CO
2
, and SO
2
•
Water vapor (Note that water vapor condensation on the gold film can cause irreparable
harm to the sensor and must be avoided.)
The C/M filter (AZI P/N: Z2600 3928), an acidic gas filter contained in the internal filter system,
removes the following compounds that cause the gold film sensor to respond:
•
Chlorine
•
NO
2
•
Hydrogen Sulfide (H
2
S)
•
Most mercaptans (organic sulfur compounds or “thiols”)
In areas containing these highly volatile compounds, the filter can quickly become saturated. In
such situations, it is recommended that these gases be allowed to dissipate before sampling for
the less volatile, more persistent mercury vapor. In addition, a special filter designed to remove
chlorine gas from the sample stream is available from Arizona Instrument and may be ordered as
Chlorine Filter, AZI P/N Z2600-3940.
Ammonia in very high concentrations can cause an off-gassing of accumulated acidic fumes
from the internal acidic gas filter, resulting in positive readings on the instrument. In these cases,
the ammonia odors are very strong. A special filter designed to remove ammonia gas from the
sample stream is available from Arizona Instrument and may be ordered as Ammonia Filter, AZI
P/N 990-0193. Again, either allow the vapors to dissipate or use the ammonia filter. Filter
replacement at regular intervals, or when unexpectedly high readings are encountered in areas of
these potential interferences, may resolve these problems.
Visit the “Tech Notes” section at
for more information concerning the chlorine
and ammonia filters.
Volatile mercury compounds in general will cause the gold film to respond. Alkyl organic
mercuries such as methyl mercury (and other “straight chained” compounds) are typically
extremely volatile and change the electrical resistance of the gold film sensor. Any such
responses should be considered “qualitative,”
not
quantitative. The instruments are designed and
calibrated to elemental mercury vapor only.
Inorganic mercury salts such as mercuric chloride are not very volatile. They may, however,
generate some minute level of elemental mercury vapor to which the instruments will respond.
This response, again, should be considered a qualitative response only.
