Devices, systems and methods for analyzing fluid streams
Certain embodiments described herein are directed to systems and methods that can be used to analyze species in a fluid stream. In some configurations, a sorbent tube effective to directly sample aromatics and/or polyaromatics in a fluid stream is described.
1. A method of analyzing a liquefied petroleum gas stream to detect the presence of BTEX and PAHs analytes within a range of C4 to C44 in the liquefied petroleum gas stream, the method comprising:
introducing the liquefied petroleum gas stream into a sorbent tube comprising a plurality of different sorbent materials that together reversibly adsorb each of the BTEX and PAHs analytes within the range of C4 to C44 in the liquefied petroleum gas stream, wherein the liquefied petroleum gas stream is heated and maintained above its bubble point as it is introduced into the sorbent tube, the sorbent tube comprising at least three different sorbent materials packed into the sorbent tube with a sorbent material with a strongest adsorption strength packed closest to an outlet of the sorbent tube and a sorbent material with a weakest adsorption strength packed closest to an inlet of the sorbent tube, wherein each of the at least three different packed sorbent materials is separated from each other by a fluid permeable barrier present between each of the at least three different packed sorbent materials, wherein an entire internal volume of the sorbent tube is occupied by the at least three different packed sorbent materials that are separated by the fluid permeable barrier present between each of the at least three different packed sorbent materials, in which one of the packed sorbent materials comprises glass beads adjacent to the inlet of the sorbent tube, wherein the glass beads comprise a surface area to adsorb BTEX and PAH analyte species with 22 carbons or more in the liquefied petroleum gas stream, and wherein other sorbent materials packed in the sorbent tube together adsorb the BTEX and PAH analytes within a range of C4 to C44 other than the BTEX and PAH analyte species with 22 carbons or more adsorbed by the glass beads, wherein the at least three different packed sorbent materials of the sorbent tube comprise the glass beads adjacent to the inlet of the sorbent tube and at least two different graphitized carbon black materials packed in the sorbent tube with none of the sorbent materials packed in the sorbent tube being the same;
individually and sequentially thermally desorbing each of the adsorbed BTEX and PAH analytes within the range of C4 to C44 from the packed sorbent materials in the sorbent tube using an oven to heat the sorbent tube comprising the BTEX and PAH analytes adsorbed to the at least three different packed sorbent materials in the sorbent tube; and
detecting each of the individually and sequentially thermally desorbed BTEX and PAHs analytes by providing each of the individually desorbed BTEX and PAHs analytes to a detector.
2. The method of claim 1 , further comprising individually thermally desorbing the adsorbed analytes from the at least three different packed sorbent materials in the sorbent tube using automated thermal desorption.
3. The method of claim 2 , further comprising condensing the individually desorbed analytes prior to separation of the desorbed analytes by chromatography.
4. The method of claim 3 , further comprising vaporizing the condensed analytes.
5. The method of claim 4 , further comprising separating the vaporized analytes using gas chromatography after vaporization of the condensed analytes.
6. The method of claim 5 , further comprising sequentially detecting each of the separated, desorbed analytes to determine the amount of each of the BTEX and PAHs analytes within a range of C4 to C44 in the liquefied petroleum gas stream, by providing each of the separated, desorbed analytes to the detector.
7. The method of claim 6 , further comprising heating the sorbent tube during the desorbing to remove all the adsorbed BTEX and PAH's analytes within a range of C4 to C44 from the sorbent materials in a single desorption cycle.
8. The method of claim 7 , further comprising introducing a carrier gas as a reverse flow during the desorption step.
9. The method of claim 1 , further comprising introducing the liquefied petroleum gas stream without any liquid extraction or canister capture of the liquefied petroleum gas stream prior to the introducing step.
10. The method of claim 1 , further comprising detecting each of the individually desorbed BTEX and PAHs analytes using a flame ionization detector.
11. The method of claim 10 , further comprising providing the individually desorbed BTEX and PAHs analytes to a gas chromatography column to separate the individually desorbed analytes using gas chromatography prior to detecting each of the individually desorbed BTEX and PAHs analytes.
12. The method of claim 1 , further comprising drawing the liquefied petroleum gas stream comprising the BTEX and PAHs analytes into the sorbent tube using a pump fluidically coupled to the sorbent tube.
13. The method of claim 1 , wherein the at least three different sorbent materials further comprise two or more different glass beads.
14. The method of claim 1 , wherein the sorbent tube comprises an internal surface feature comprising caps, chevrons, or fins.
15. The method of claim 1 , wherein a mesh size of the each of the packed sorbent materials is 20 to 100 mesh.
16. The method of claim 1 , wherein the sorbent tube comprises stationary fluid permeable barrier at one end of the sorbent tube and a clip at another end of the sorbent tube, wherein the clip retains the at least three different packed sorbent materials in the sorbent tube.