Service manual
Reducing Vaporization Mercury Analyzer Mercury RA-4500
25
5.
Measures against abnormality
5.1.
Abnormal blank value
Possible causes of an abnormal blank value are as follows:
- Contaminated reagent or distilled water
- Contaminated sample container or stirring bar
- Contaminated instrument
- Rise in the mercury concentration in the atmosphere (air)
In the case of an abnormality, replace or clean components or replace reagents.
It is possible to narrow down causes in the following procedure:
(1) Measure distilled water without heating or cooling.
OK: Pretreatment reagents or the environment has been contaminated (indoor
pollution).
NG:
The distilled water, sulfuric acid, stannous chloride solution, cap, tube or
detector is defective.
(2) In the case of NG in (1), measure the solution used in (1) as it is.
OK: The cause is the distilled water.
NG:
The sulfuric acid, stannous chloride solution, cap, tube or detector is
defective.
(3) In the case of NG in (2), set the quantities of the reagents to 0 mL in the
measuring condition, and remeasure the solution measured in (2).
OK: The cause is the contamination of the sulfuric acid, tin reagent or reagent
pump tube.
NG:
The cap, tube or detector is defective.
(4) In the case of OK in (1), set the quantities of the reagents other than the tin to a
half, and measure distilled water with pretreatment.
Decrease: The cause is the contamination of a pretreatment reagent or a reagent
tube.
No change: The cause is the contamination of the environment. (A mercury
concentration of several tens ng/m3 or more is expected.) Clean the inside of the
room.
* Even when the time is shortened, make the heating time 30 minutes or more. It
is impossible to measure mercury in pretreatment reagents without heating.
(5) In the case of decrease in (4), change the quantity of each reagent and conduct
verification.
* Potassium permanganate and hydroxylammonium chloride are reagents that
are contaminated easily.
When the blank value will decrease if a reagent is poured with a pipette or the like, the
cause is a contaminated reagent tube.