![]() |
| |
Autosampling system for gas chromatography | ||||
![]() |
|||||
| Content | |||||
| Features and advantages | |||||
|
|||||
| Principle and flow chart | |||||
| The new device concept allows for the first time a direct purging of volatile substances from 20 ml vials, which can be filled with solid or liquid samples. Each vial is moved into a heated sample unit, where a long and a short needle penetrates the sealing septum. All volatile substances are purged and enriched in the micro-packed trap. Here the substances are froozen out with liquid nitrogen or CO2 or a Peltier cooler and finally transferred by fast thermal desorption to the gas chromatograph. As the purged water is seperated from the sample in a chemical, membrane or peltier water-trap, very sensitive detectors like a flame ionization detector, a mass spectrometer or an atomic emission detector can be used. Via a sample loop additionally internal standards or regents can be added into the sample. After processing a sample, the needles and the watertrap are backrinsed with carrier gas, impurities and water are removed securely from the system. | |||||
![]() |
|||||
| Conventional technique vs. "in vial purging" | |||||
| The following figures show the gas flow of the conventional technique and the "in vial purging" of the PTA3000. The advantages during the purging process can be seen: | |||||
![]() |
|||||
| Micro-packed trap | |||||
| The system performance and low detection limits attainable with the PTA3000 are particularly due to the very small adsorbent volume in the micro-packed trap. In the stable trap with an outside diameter of 1/16" different adsorbents (Cromosorb G HP, Tenax TA...) can be micro-packed. The minimum thermal mass of the trap allows a fast desorption with approx. 900°C/min , whereby excellent peak forms are obtained. | |||||
| Cryo-focussing with LN2, CO2 or Peltier | |||||
| During the purging
process the purged substances are concentrated by freezing out in the mikro-packed
trap. The cooling of the trap can be reached by different techniques: liquid nitrogen LN2: -160°C, 10 l Dewar liquid carbon dioxide CO2: -65°C, CO2-bottle Peltier elements: -35°C, water cooling system with integrated sensor control |
|||||
| Available water traps | |||||
| With the analysis
of water samples it is important to separte the purged water. According
to the substances the separation can be done with differnet water trap techniques: PWT Peltier water trap: polar substances CWT chemical water trap: for non-polar substances MWT membrane water trap: non-polar substances none: for all substances, only for absolute dry samples The water traps hold back up to 99.98% of the purged water and allows perfect chromatography. Since the water traps are installed on the top side of the PTA3000, a simple exchange is possible. |
|||||
| Analytical performance | |||||
| The micro-packed trap, kryo focussing, inert lines and the "in-vial-purging"guarantee best performance and low detection limits. In the following some chromatograms and the list of measured substances are shown: | |||||
|
|||||
| If you
have any questions or problems with your purge-and-trap system do not hesitate
to contact us. We can send you different chromatograms in the range of food, liquids, soils, spices, cardboard, paper, oils... |
|||||
| Method configuration | |||||
| The editing of the methods can be done dialog-guided and directly via the PTA3000 keyboard or with the method editor PTAWIN at the PC. Up to 30 different methods can be stored in the PTA3000. The possible method parameters and the appropriate input limits become obvious from the following PTAWIN mask: | |||||
![]() |
|||||
| Technical data | |||||
| Vials: | number: 20; volume: 20ml; dimensions: D=23mm; H=79mm; septa: silikon-PTFE (ultra low bleed) | ||||
| Trap: | diameter: 1/16" glas lined tube; Chromosorb or Tenax or customer specific | ||||
| Signals and interfaces: | RS232; GC-Ready; GC-Start; PTA-Ready | ||||
| Electrical control: | 16bit processor; 512k RAM; 128k ROM; graphic display 240x128 pixel | ||||
| Installation conditions: | power supply: 230V; 50 Hz; power consumption: 450VA; weight: 20 kg; ambient temperature: 15-25°C | ||||
| GC-connection: | via transfer line or direct | ||||
| Gases: | carrier gas: He 5.0; cryogenic gases: LN2 or CO2; dry N2 | ||||
| |
|||||
![]() |
|||||
| |
|||||
| © 2009 Copyright / Disclaimer |