Metrohm 817 Bioscan - Manual (Page 69)

5.3 Faults and malfunctions
817 Bioscan
61
5.3 Faults and malfunctions
5.3.1 Malfunctions and their rectification
If difficulties appear with the IC system during analyses, their causes
are best investigated in the order separating column
→ pump →
eluent
→ 817 Bioscan. Several of the malfunctions which may appear
are listed in the following table with details of possible causes and
countermeasures.
Malfunction Cause Rectification
Baseline with high
noise level,
pulsation • Contaminated pump
values
• Faulty piston seals
• Quality of the pump
does not suffice for the
selected sensitivity
• Air bubble in flowcell
• Temperature fluctuation
• Working electrode
contaminated
• Flowcell leakage
• Eluent contaminated
• Clean the valves (see
section 5.1.2)
• Replace the piston seals
(see section 5.1.2)
• Use pulsation dampener,
use more powerful pump
or lower the sensitivity
• Remove air bubble, degas
eluent continuously
• Isolate flowcell or switch
on 817 Bioscan oven
• Clean working electrode
(see Chapter 5.2.3)
• Check capillary connec-
tions at flowcell
• Replace eluent
Drift of the
baseline
• Thermal equilibrium not
yet reached
• Leak in system
• Old Eluent (too much
CO2)
• Condition system with
heating switched on
• Check connections and
make leakproof
• Replace eluent
Decreasing
sensitivity
(S/N lower) • Working electrode
contaminated, e.g. by
contaminated sample
• Wrong measuring
potential
• Eluent contaminated
(high background
signal)
• Eluent pH changed
• Clean working electrode
(see Chapter 5.2.3), dilute
sample
• Optimize measuring
potential
• Replace eluent
• Check and adjust pH
High background
signal • Eluent contaminated
• Wrong measuring
potential / pulse settings
• Very broad peaks due to
retarded compounds
• Separation column is
bleeding
• Replace eluent
• Optimize parameter
• Await complete elution of
these compounds
• Replace column