HPLC Valve Options


PAL 3-Valve Module
The PAL 3-Valve Drive Module consists of 3 individually controlled valve drives which are arranged in a vertical stack. The top valve acts as injection valve, while the remaining 2 valves are used as switching valves. Typical applications are pre-column SPE, pre-column cleanup, sample desalting etc.
For increased sample throughput the accessory can be used for time staggered "heart- cuts" of two independent gradient systems. Important chromatogram parts only reach the detector through a selector valve just in time, while the frontand end-cut goes to waste. The compact arrangement results in a space saving setup with very short connection lines.
Precise switching times are provided by the PAL control software Cycle Composer. The module is compatible either with 4- 6- or 10-port injection valves or with a 8-port stream selector valve. Furthermore the different valve types can also be mixed on the same 3-Valve Drive Module.

Flow Diagram 1


Valve 1

Injection valve Early valve switch for washing
and prep ahead next sample.

Valve 2

Pre-column or SPE cartridge Front cut to
eliminate e.g. proteins or other high molecula

Valve 3

Analytical column or 2nd pre-column
Early backflush of late eluting compounds

PAL 2 Valve module

When columns must be regenerated following each analysis, this technique permits automation of the process. While one column performs the analysis, the second column undergoes regeneration by use of an auxiliary pump. Once the first analysis is complete, the valve is switched and the regenerated column is now ready for analytical use.

Flow diagram 2

(altnernate column regeneration)
Injection on column 1, column 2 will be regenerated
At valve toggle (switch) the injection is perfomed on
column 2 and column 1 will be regenerated (conditioned)
for next injection.
The column can be an analytical or a pre-column for fast
elimination of high molecular compounds.

6-port Microbore Injection Valve
A 6-port Cheminert Injection Valve with 0.25mm bore is available used for microbore applications. It can replace the standard valves with bore 0.40mm. The Cheminert Microbore Valve is recommended for flow rates ~10 - 400µl/min. and LC column ID's of 0.3 - 2mm. It is shipped with a special 10µl sample loop (0.025mm ID).


Metal free Injection Valve
Some LC analyses require an inert, metal free solvent/sample path (e.g. bioanalysis, Ion chromatography). For such applications a metal free LC Injection Valve is available. The inert valve kit consists of a 6-port Cheminert flat plate rotary valve with PAEK stator, a 20 µl PEEK sample loop, a PEEK needle guide and 6pcs. PEEK fittings/ferrules 1/16 inch.



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