INFICON HAPSITE Smart Plus Chemical Identification System - Manual (Page 467)

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HAPSITE Smart Plus Operating Manual
14.9 Background Cleanup
14.9.1 Introduction
The SituProbe / HAPSITE system, with Concentrator installed, routinely detects
VOCs at the ppt level. Occasionally, an operator may unknowingly expose the
system to an excessively high VOC level resulting in carryover in subsequent blank
analyses. The chromatogram indications of carryover can be broad baseline
increases or individual peaks of the analytes or other matrix VOCs that persistently
appear. Polymer components such as PEEK™ tubing in Transfer Lines and
Teflon® in Diaphragm Valves are likely sources of carryover. If the background
persists after a few blank runs with clean water then more aggressive measures
may be required.
14.9.2 Cleanup Steps
14.9.2.1 Probe Head
Because the contamination must originate with the water sample, the probe head
should be cleaned. Thoroughly rinse the probe head with VOC-free water. Unscrew
the glass or plastic purging sleeve being careful not to damage the other
components in the probe head. The sealing o-ring can also be removed and rinsed
with water. Clean the sleeve in detergent followed by thorough rinsing with
VOC-free water. Gently wipe the probe head components and surfaces that show
signs of contamination. Re-install the purging tube.
NOTE: The purge tube and o-ring are replaceable items.
14.9.2.2 HAPSITE
A simple troubleshooting step will determine if the contamination is in the HAPSITE
as well as the SituProbe. Disconnect the transfer line from the HAPSITE and attach
the air-sampling probe. Perform a blank run while sampling clean air or Nitrogen
and compare the background and/or contamination peaks to the SituProbe blanks.
Repeat once or twice if necessary. If the contaminant is only in the SituProbe, then
continue directly to the SituProbe cleanup procedure below. If the contaminant is
in the HAPSITE, then the HAPSITE and SituProbe will require the cleanup
procedure. The HAPSITE should be baked out by setting the heated zones to
higher temperatures for a few hours, followed by blank runs using a HAPSITE Loop
method or a default HAPSITE "cleanout" method (air-probe sampling,
Concentrator installed) as appropriate.
14.9.2.3 SituProbe FLUSH
The SituProbe has a built-in FLUSH mode for system cleanup. To prepare for this
operation, remove the transfer line at the HAPSITE connection. Leave the transfer
line connected to the SituProbe. Remove the probe head from the water vessel and
lay it on a clean surface. If possible connect the SituProbe to a bulk Nitrogen
cylinder, although an on-board canister can be used for shorter periods of time.