Methods and systems for characterizing a sorbent tube
View Patent ↗Disclosed are systems and methods that include providing a vessel having an adsorbent disposed therein, the vessel having an inlet and an outlet for communicating a carrier gas through the vessel; determining a differential pressure between the inlet and the outlet for a known flow rate at the outlet; and, determining a geometric measure for the vessel based on a ratio of the known flow rate and the differential pressure. In some embodiments, the methods and systems can include a viscosity in the ratio, determining a flow rate at ambient pressure using a factor based on a ratio of a gas pressure at the output and ambient pressure, and/or, determining a flow rate at ambient temperature using a factor based on a ratio of a temperature at the output and ambient temperature.
1. A chromatographic method, comprising:
providing a vessel in a carrier gas flow path to a chromatographic column, the vessel comprising:
a gas inlet,
a gas outlet, and,
an adsorbent disposed in the vessel,
measuring a differential pressure along the length of the adsorbent,
determining a flow rate at the outlet, and,
determining a unit flow per unit pressure based on a ratio of the flow rate and the differential pressure.
2. The method of claim 1 , further comprising adjusting the unit flow per unit pressure based on a viscosity of the gas.
3. The method of claim 1 , further comprising at least one of:
determining a flow rate at ambient pressure using a factor based on a ratio of a gas pressure at the output and ambient pressure, and,
determining a flow rate at ambient temperature using a factor based on a ratio of a temperature at the output and ambient temperature.
4. The method of claim 1 , further comprising heating the vessel to desorb analytes from the adsorbent.
5. The method of claim 1 , wherein the vessel comprises an adsorbent trap.
6. The method claims 1 , wherein the vessel comprises a sample tube.
7. The method of claim 6 , further comprising:
providing a second vessel in the carrier gas flow path to the chromatographic column, the second vessel comprising:
a gas inlet,
a gas outlet, and,
an adsorbent disposed in the second vessel,
measuring a differential pressure along the length of the adsorbent disposed in the second vessel,
determining a flow rate at the outlet of the second vessel, and,
determining a second unit flow per unit pressure based on a ratio of the flow rate at the outlet of the second vessel and the differential pressure along the length of the adsorbent disposed in the second vessel.
8. A chromatographic method, comprising:
providing a vessel in a carrier gas flow path to a chromatographic column, the vessel comprising:
a gas inlet,
a gas outlet, and,
an adsorbent disposed in the vessel,
measuring a differential pressure along the length of the adsorbent, and
relating the differential pressure to a flow rate at the outlet to determine a unit flow per unit pressure based on a ratio of the flow rate and the differential pressure.
9. The method of claim 8 , further comprising adjusting the unit flow per unit pressure based on a viscosity of the gas.
10. The method of claim 8 , further comprising establishing the flow rate at the outlet by controlling the flow of the gas.
11. The method of claim 8 , wherein the vessel comprises an adsorbent trap.
12. The method claims 8 , wherein the vessel comprises a sample tube.
13. The method of claim 12 , further comprising:
providing a second vessel in the carrier gas flow path to the chromatographic column, the second vessel comprising:
a gas inlet,
a gas outlet, and,
an adsorbent disposed in the second vessel,
measuring a differential pressure along the length of the adsorbent disposed in the second vessel, and,
relating the differential pressure along the length of the adsorbent disposed in the second vessel to a flow rate at the outlet of the second vessel to determine a second unit flow per unit pressure based on a ratio of the flow rate at the outlet of the second vessel and the differential pressure along the length of the adsorbent disposed in the second vessel.