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Loss of sensitivity or excessive drift
Several possible causes exist for overall deterio-
ration of the chromatogram.
• Contamination in the valve requires a thor-
ough cleaning.
• Internal leakage requires a complete disas-
sembly and inspection of the mating sur-
faces.
• Poor temperature control may require a full
check of electronic and thermal components.
• Lack of proper conditioning techniques, col-
umns, etc.
• Failure or deterioration of other components
(columns, detectors, etc.).
Released: April 2004
Loss of peaks in specific areas of the
chromatogram
Entire sections of chromatographic data can be
lost due to a valve that does not rotate or one
that rotates improperly. Other than obvious
component failures (solenoid, actuator, etc.),
improper adjustments and misalignments cause
most problems.
• Check that adequate air (about 482 kPa or
• Check the valve. Is it rotating?
• If the valve rotates, check for proper align-
• Check for blocked flow paths with valve in
6850 Series Gas Chromatograph Service Procedures
70 psi) is supplied.
ment of the actuator, mechanical binding or
slippage of connecting parts.
both positions.
334
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