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Utilization of sample preconcentration to improve sulfur detection limits in chemiluminescent and pulsed flame photometric detection

IP.com Disclosure Number: IPCOM000030178D
Publication Date: 2004-Jul-30
Document File: 11 page(s) / 85K

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The IP.com Prior Art Database

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Utilization of sample preconcentration to improve sulfur detection limits in chemiluminescent and pulsed flame photometric detection

Summary:

As the requirement for lower levels of sulfur determination increase, the need for stable measurements at those levels will also increase.  There are two predominant technologies utilized today for the determination of S at levels below 1 ppm:  Sulfur chemiluminescent detection (SCD) and pulsed flame photometric detection (PFPD).  A previous study (Talbert, B., Benesch. R., Jacksier., T. “A Comparison of the Sulfur Chemiluminescent and Pulsed Fame Photometric Detectors for the Analysis of Low Level Sulfur Components, Proceedings of the 2002 Natural Gas Quality Conference, 2002) it was determined that the detection limits of the SCD were significantly lower when compared to the PFPD, however, the stability of the PFPD was significantly better.  The objective of this study was to try to lower the detection limits of the PFPD utilizing sample preconcentration.  However, only the feasibility was tested with the SCD.

The method contained herein describes how to decrease the detection limit of sulfur compounds by SCD utilizing a sample preconcentration  trap.  It is envisioned that this will be directly transferrable to the PFPD thereby gaining comparable detection limits and enhanced stability. 

BACKGROUND REFERENCES:

PFPD:  5153673, 5686656,

SCD:  5501981, 5661036, 6130095, 6458328 B1

Sample concentration:  6,223,584 B1

Each of these references is hereby incorporated in its entirety into this document.

 

 

 

Experimental set-up

1.1.           Instruments

In this experiment, it is necessary to use two gas chromatographs that are linked together with a column. The reason for that is that the SPT we are trying to evaluate is integrated in the Varian 3800 GC whereas some components of the SCD (furnace, ceramic tubes) are integrated in the Agilent 6890 GC. Moreover, the SPT and the SCD are controlled by two different software: Saturn Workstation for SPT and Chemstation for SCD.

Gas Chromatographs:

Ø       Varian 3800 GC: Oven Temperature = 220°C; Column Flow Rate = 5 mL/min; Split Ratio = 10:1

Ø       Agilent 6890 GC: Oven Temperature = 80°C

Varian SPT: it is fully integrated into the GC. A short trap is used with liquid Nitrogen for cryogenic cooling. Even though the trap could be filled with adsorbents such as Tenax or charcoal-based materials, in our case glass beads are used as the trapping material. The SPT is controlled and programmed using the Saturn Workstation. The short trap has the following characteristics: Active Bed Length = 6.8 cm, Total Length = 17.02 cm, Volume = 480 mL.

Column: the column used is a 60 m GS-Gaspro from J&W.

Antek SCD: the SCD used is an Antek 7090, which is connected to the Agilent 6890 GC by a transfer line made out of Silcosteel tubing. The following parameters are used for the SCD:

-          Furnace Temperature = 950°C

-          Oxygen Flow Rate = 5 mL/min

-          Hydrogen Flow Rate = 125 mL/min

-          Ozone Flo...