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117
These illustrations showbasic sample injection techniques
usingValco twopositionvalves. With rareexceptions, there
isnodifferencebetween switchingvalvesandexternal
volume samplingvalves,so the samevalvecanbeused
for either function.
Theuniqueadvantageof 8and10port valves is that
they reduceextracolumnvolumebycombining sampling
and switching functions ina singlevalve. Thisminimizes
expense,maintenance,service,and riskof leaksas
compared tomultiple6port valve systems.
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MicrovolumeSample Injection
The internal sample (fixedvolume)
flowpath isusedwhenvery small sample
volumesare required. The sample size is
determinedbyapassageengravedon the
valve rotor,allowingprecise, repeatable
injections. InPositionA, the sample
flows through the samplepassagewhile
themobilephaseflows through to the
column. The thirdpassage is inactive. In
PositionB, the samplepassage is in line
with thecolumnand themobilephase
injects thecontentsof the samplepassage
onto thecolumn.Thepassagewhichwas
inactive inPositionAallows the sample to
continueflowingwithout interruption.
DualMicrovolumesample
Injection
Thismicrovolume injector canbeused to
alternatebetween twodifferent samples.
Each time thevalve is switched,a sample
is injected. Byconnecting the two sample
inlets in series, thevalve injects the sample
each time thevalve switches. This is
particularlyuseful inheavydutycycle
operations tominimizevalvewear. The
valvecanalsobeused tomakealternating
injectionsof the same sampleonto two
different columnsby swapping sample/
wasteandpump/columnconnections.
Note:
ThisC
I
6valve isnot shown
in this catalog. Call fordetails.
TwoPositionApplications
6port internal sample injector
4port internal sample injector
CHROMalyticTECHnologyPtyLtdAUSTRALIANDistributors e-mail:
: 03 97622034
