PREP 9000
Micro-Preparative techniques allows
you to .......
Separate complexe mixtures and structural isomeres......
Isolate impurities for identification or for use as standards......
Collect components for further use e.g. NMR......
The new PREP9000 System based on the SNIFFER 9000 System has been completely redesigned in order to fit to the future needs. The system now is available as a stand alone unit to be installed to any GC available on the Market. The PREP9000 System has been designed to be a dedicated Preparative System connected to any GC available on the market by using a flexible heated interface line to the preparative unit. The new Electronic- and Pneumatic design , based on the new industry standard (LON) allows the system to be as flexible as possible for the future needs and to protect your investements in the Laboratory.
The Micropreparative technique
The enrichment procedure is based on a repetitive adsorption of eluting compounds, after separation from a capillary column, by sucking them trough an adsorption tube mounted on the outlet splitter. Optimisation is easily performed during a supervised GC run in a semi automatic mode. Repetitive sample processing becomes possible today with the aid of computers. Using simple logical decisions, they are able to reliable supervise even complex systems. Based on the FID signal of a reference substance the system directs the column effluent at any given time (using the time events table of any Data Handling System) into the collecting system where the individual compounds of interest are adsorbed.
Principle of operation
The mixture to be separated are filled into standard Autosampler Vials which are placed into a Automatic Sampler. The sample will be injected using the On-Column technique on conditioned 0.32 mm i.d. capillary columns. Small glass tubes filled with an adsorbent are used for sample enrichment. They are fixed in a special designed revolving drum which is screwed on a additional detector base body heated by the standard detector heating block. One branch of an exit splitter leads through available PRES-FIT T-piece.
During normal run conditions the whole column effluent flows into the detector. On changing to the switch condition the effluent can be directed completely or partially into the adsorption tubes. This is accomplished by the following mechanism:
The adsorption tube placed directly above the splitter branch is connected to vacuum. The vacuum is activated byswitching a solenoid valve opening the circuit to the vacuum pump. On sucking, the whole effluent can be passed through the adsorption tube, so efficiently that the flame of the FID can even be extinguished.
During normal operation the solenoid valve is closed. Thus a standing gas volume, serving as a gas barrier, is obtained in the splitter branch leading the adsorption tube. Therefore, the column effluent is forced to flow through the splitter branch leading to the FID and does not contaminate the adsorption tube.
Changing over from one fraction to another is performed by turning the pneumatically driven revolving fraction collector. This procedure needs about 2 seconds. Any loss of sample during this time can be neglected, particularly since it is preferable anyway to collect neighbouring peaks in such a way that the overlapping zone, which is generally larger than 2 seconds, is not collected. For resolved peaks, the sample loss between the peak valleys is negligible. Generally, the ratio between bleed and sample improves if the eluting sample is not collected at the bottom of either slope. Furthermore, the information gained from a spectrum of pure sample is more valuable than from a sample containing 10 to 20% impurities. Collected fractions can be stored or be desorbed with a suitable solvent for subsequent analysis, e.g. NMR, UV, IR, micro chemical reactions, and biological activity tests.