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3.3.2 Abnormal blank value
The primary cause of a high blank value is the mercury pollution of the piping route. If the
blank value increases because of a dirty component, measurements in the low
concentration region will be difficult. Pinpoint the dirty part and clean or replace the
component.
The dirty part can be pinpointed by attaching a mercury removal filter to various parts of
the piping route and making comparison measurements. Attach activated carbon for a
filter or a mercury collector tube to various parts of the piping route using Tygon tubes or
the like, and make measurements.
* When standard gas is collected, a mercury grain may adhere to the syringe needle,
and the standard gas injection port may be polluted. Carry out an injection after wiping
the needle end using Kimwipe or the like.
3.3.3 Abnormal rise in sensitivity
Possible causes of a rise in the peak sensitivity are the following two failures:
Abnormal standard gas: Mercury pollution of syringe, low display temperature of
gas box, polluted septum in gas box
Decrease of flow between H2 and absorption cell: Leak, clogged collector tube,
abnormal pump
