Separate Argon from Oxygen Above Ambient Temperatures
Using an Rt-Msieve 5A PLOT Column
- Fast, efficient separations at above ambient temperatures.
- High permeability and narrow column diameter mean sharper peaks.
- 100% bonding process eliminates the need for particle traps.
Porous layer open tubular columns—PLOT columns—offer significant advantages over packed gas-solid chromatography (GSC) columns. The open tubular design gives PLOT columns greater permeability, and their narrow diameter ensures sharper peaks. The open construction affords a smaller pressure drop per unit length, so longer columns can be used. This means much higher column efficiency and, therefore, superior resolution. In brief, PLOT columns provide faster and more sensitive analyses than packed GSC columns.
Restek PLOT columns are especially effective for separating mixtures of gaseous analytes. Rt-Msieve 5A PLOT columns contain molecular sieve 5A particles that are bonded to prevent particle dislocation, thus protecting valves and detection systems from damage. They are designed for fast, efficient separation of argon and oxygen, hydrogen and helium, and other permanent gases, including permanent gases admixed in refinery or natural gas. Finely controlled pore size allows selective adsorption of specific target compounds, ensuring that difficult separations can be made without subambient temperatures.
Figure 1 shows a 30 m x 0.53 mm ID Rt-Msieve 5A PLOT column can separate oxygen from argon to baseline, at above ambient temperature, in approximately 4 min. Also, the permanent gases are resolved from methane in the same analysis. Carbon dioxide does not elute from a molecular sieve 5A column, but can be chromatographed on an Rt-Q-BOND porous polymer column.
If your analyses call for difficult separations of gaseous analytes, and neither conventional packed GC columns nor WCOT capillary columns are providing the separations you want, or if your analyses depend on costly or time-consuming conditions, a Restek PLOT column may be your solution.
Figure 1: Excellent resolution at above ambient temperatures on an Rt-Msieve 5A PLOT column.
| Column | Rt-Msieve 5A, 30 m, 0.53 mm ID, 50 µm (cat.# 19723) |
|---|---|
| Standard/Sample | Permanent gases |
| Injection | sample valve |
| Sample Loop Vol.: | 5 µL |
| Valve Name: | 6-port Valco valve |
| Inj. Temp.: | 200 °C |
| Valve Temp.: | Ambient °C |
| Oven | |
| Oven Temp.: | 27 °C (hold 5 min) to 100 °C at 10 °C/min (hold 5 min) |
| Carrier Gas | He, constant flow |
| Flow Rate: | 5.0 mL/min |
| Detector | Valco helium ionization detector @ 150 °C |
|---|
PLOT Column Advantages
Gas-liquid chromatography (GLC), the most common mode of gas chromatography, has limited application in analyses of gases. Subambient temperatures often are required to achieve a separation, and cryogenic cooling systems are costly and inconvenient.
Gas-solid chromatography (GSC), in which gaseous analytes are adsorbed onto the packing particles, rather than into a surface coating, is far more effective for separating gases. Difficult-to-separate small molecules, such as argon and oxygen, ethane isomers, and many others, can be separated by GSC at above ambient temperatures.
When analyzing gases, PLOT columns offer significant advantages over both GLC and GSC packed columns, including:
- Excellent separations at above ambient temperature; no costly cooling systems required.
- Sharper peaks, due to smaller tubing internal diameters.
- Higher efficiency and greater sensitivity.