The authors would like to acknowledge support from the Government of Canada's interdepartmental Program of Energy Research and Development, PERD 113, Petroleum Conversion for Cleaner Air. N.E.H would like to acknowledge her Natural Sciences and Engineering Research Council of Canada Visiting Fellowship.

Caution: Please consult all relevant material safety data sheets (MSDS) for materials before using. In particular, CS2 is highly flammable and should be stored and handled appropriately. H2S gas is highly toxic, and any containers or gas bags containing H2S should not be opened or handled outside of a properly vented fumehood. Work with crude oil samples should only be done with full personal protective equipment (gloves, safety glasses, lab coat, pants and closed-toe shoes), and all crud...

<ol>
	<li>Guidotti, T. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hydrogen+sulphide.">Hydrogen sulphide.</a> Occ. Med. 46, 367-371 (1996).</li><li>Reiffenstein, R. J., Hulbert, W. C., Roth, S. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Toxicology+of+Hydrogen+Sulfide.">Toxicology of Hydrogen Sulfide.</a> Annu. Rev. Pharmacol. Toxicol. , 109-134 (1992).</li><li>Qi, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+Temperature+on+the+Corrosion+Behavior+of+Carbon+Steel+in+Hydrogen+Sulphide+Environments.">Effect of Temperature on the Corrosion Behavior of Carbon Steel in Hydrogen Sulphide Environments.</a> Int. J. Electrochem. Sci. 9, 2101-2112 (2014).</li><li>Ma, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+influence+of+hydrogen+sulfide+on+corrosion+of+iron+under+different+conditions.">The influence of hydrogen sulfide on corrosion of iron under different conditions.</a> Corros. Sci. 42, 1669-1683 (2000).</li><li>Kallinikos, L. E., Jess, A., Papayannakos, N. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Kinetic+study+and+H2S+effect+on+refractory+DBTs+desulfurization+in+a+heavy+gasoil.">Kinetic study and H2S effect on refractory DBTs desulfurization in a heavy gasoil.</a> J. Catal. 269, 169-178 (2010).</li><li>Liu, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Kinetic+investigation+of+the+effect+of+H2S+in+the+hydrodesulfurization+of+FCC+gasoline.">Kinetic investigation of the effect of H2S in the hydrodesulfurization of FCC gasoline.</a> Fuel. 123, 43-51 (2014).</li><li>Si, X., Xia, D., Xiang, Y., Zhou, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+H2S+on+the+transformation+of+1-hexene+over+NiMoS/&#947;-Al2O3+with+hydrogen.">Effect of H2S on the transformation of 1-hexene over NiMoS/&#947;-Al2O3 with hydrogen.</a> J. Nat. Gas Chem. 19, 185-188 (2010).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Hydrogen Sulfide and Mercaptan Sulfur in Liquid Hydrocarbons by Potentiometric Titration. , UOP 163-10 (2010).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Standard Test Method for Determination of Hydrogen Sulfide in Fuel Oils by Rapid Liquid Phase Extraction. , ASTM D7621-10 (2010).</li><li>Lywood, W. G., Murray, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> H2S in Crude Measurement Report. , (2012).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Standard Test Method for Sulfur Compounds in Light Petroleum Liquids by Gas Chromatography and Sulfur Selective Detection. , ASTM D7621-10 (2009).</li><li>Liu, W., Morales, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Detection of Sulfur Compounds According to ASTM D5623 in Gasoline with Agilent's Dual Plasma Sulfur Chemiluminescence Detector (G6603A) and an Agilent 7890A Gas Chromatograph. , (2008).</li><li>Barman, B. N., Cebolla, V. L., Membrado, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chromatographic+Techniques+for+Petroleum+and+Related+Products.">Chromatographic Techniques for Petroleum and Related Products.</a> Crit. Rev. Anal. Chem. 30, 75-120 (2000).</li><li>Rodgers, R. P., McKenna, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Petroleum+Analysis.">Petroleum Analysis.</a> Anal. Chem. 83, 4665-4687 (2011).</li><li>Nizio, K. D., McGinitie, T. M., Harynuk, J. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comprehensive+multidimensional+separations+for+the+analysis+of+petroleum.">Comprehensive multidimensional separations for the analysis of petroleum.</a> J. Chromatogr. A. 1255, 12-23 (2012).</li><li>Luong, J., Gras, R., Shellie, R. A., Cortes, H. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tandem+sulfur+chemiluminescence+and+flame+ionization+detection+with+planar+microfluidic+devices+for+the+characterization+of+sulfur+compounds+in+hydrocarbon+matrices.">Tandem sulfur chemiluminescence and flame ionization detection with planar microfluidic devices for the characterization of sulfur compounds in hydrocarbon matrices.</a> J. Chromatogr. A. 1297, 231-235 (2013).</li><li>Di Sanzo, F. P., Bray, W., Chawla, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Determination+of+the+Sulfur+Components+of+Gasoline+Streams+by+Capillary+Column+Gas+Chromatography+with+Sulfur+Chemiluminescence+Detection.">Determination of the Sulfur Components of Gasoline Streams by Capillary Column Gas Chromatography with Sulfur Chemiluminescence Detection.</a> J. High Res. Chromatog. 17, 255-258 (1994).</li><li>Deans, D. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+technique+for+heart+cutting+in+gas+chromatography.">A new technique for heart cutting in gas chromatography.</a> Chromatographia. 1, 18-22 (1968).</li><li>Hinshaw, J. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Valves+for+Gas+Chromatography,+Part+III:+Fluidic+Switching+Applications.">Valves for Gas Chromatography, Part III: Fluidic Switching Applications.</a> LC GC N. Am. 29, 988-994 (2011).</li><li>Seeley, J. V., Micyus, N. J., Bandurski, S. V., Seeley, S. K., McCurry, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microfluidic+Deans+Switch+for+Comprehensive+Two-Dimensional+Gas+Chromatography.">Microfluidic Deans Switch for Comprehensive Two-Dimensional Gas Chromatography.</a> Anal. Chem. 79, 1840-1847 (2007).</li><li>Tranchida, P. Q., Sciarrone, D., Dugo, P., Mondello, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heart-cutting+multidimensional+gas+chromatography:+A+review+of+recent+evolution,+applications,+and+future+prospects.">Heart-cutting multidimensional gas chromatography: A review of recent evolution, applications, and future prospects.</a> Anal. Chim. Acta. 716, 66-75 (2012).</li><li>Armstrong, D. W., Reid, G. L., Luong, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gas+Separations:+A+Comparison+of+GasPro&#8482;+and+Aluminum+Oxide+PLOT+Columns+for+the+Separation+of+Highly+Volatile+Compounds.">Gas Separations: A Comparison of GasPro&#8482; and Aluminum Oxide PLOT Columns for the Separation of Highly Volatile Compounds.</a> Curr. Sep. 15, 5-11 (1996).</li><li>Ellis, J., Vickers, A. K., George, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Capillary+Column+Selectivity+and+Inertness+for+Sulfur+Gas+Analysis+in+Light+Hydrocarbon+Streams+by+Gas+Chromatography.">Capillary Column Selectivity and Inertness for Sulfur Gas Analysis in Light Hydrocarbon Streams by Gas Chromatography.</a> Fuel Chemistry Division Preprints. 47, 703-704 (2002).</li><li>Ji, Z., Majors, R. E., Guthrie, E. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Porous+layer+open-tubular+capillary+columns:+preparations,+applications+and+future+directions.">Porous layer open-tubular capillary columns: preparations, applications and future directions.</a> J. Chromatogr. A. 842, 115-142 (1999).</li><li>Luong, J., Gras, R., Shellie, R. A., Cortes, H. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Applications+of+planar+microfluidic+devices+and+gas+chromatography+for+complex+problem+solving.">Applications of planar microfluidic devices and gas chromatography for complex problem solving.</a> J. Sep. Sci. 36, 182-191 (2013).</li><li>Hildmann, F., Kempe, G., Speer, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Application+of+the+precolumn+back-flush+technology+in+pesticide+residue+analysis:+A+practical+view.">Application of the precolumn back-flush technology in pesticide residue analysis: A practical view.</a> J. Sep. Sci. 36, 2128-2135 (2013).</li><li>Gray, B. P., Teale, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+use+of+a+simple+backflush+technology+to+improve+sample+throughput+and+system+robustness+in+routine+gas+chromatography+tandem+mass+spectrometry+analysis+of+doping+control+samples.">The use of a simple backflush technology to improve sample throughput and system robustness in routine gas chromatography tandem mass spectrometry analysis of doping control samples.</a> J. Chromatogr. A. 1217, 4749-4752 (2010).</li><li>Hayward, T., Gras, R., Luong, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+selected+oxidation+inhibitors+in+transformer+oils+by+multidimensional+gas+chromatography+with+capillary+flow+technology.">Characterization of selected oxidation inhibitors in transformer oils by multidimensional gas chromatography with capillary flow technology.</a> Anal. Methods. 6, 8136-8140 (2014).</li><li>Hutte, R. S., Johansen, N. G., Legier, M. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Column+Selection+and+Optimization+for+Sulfur+Compound+Analyses+by+Gas+Chromatography.">Column Selection and Optimization for Sulfur Compound Analyses by Gas Chromatography.</a> J. High Res. Chromatog. 13, 421-426 (1990).</li><li>Yan, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Unique+selective+detectors+for+gas+chromatography:+Nitrogen+and+sulfur+chemiluminescence+detectors.">Unique selective detectors for gas chromatography: Nitrogen and sulfur chemiluminescence detectors.</a> J. Sep. Sci. 29, 1931-1945 (2006).</li><li>Araujo, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Key+aspects+of+analytical+method+validation+and+linearity+evaluation.">Key aspects of analytical method validation and linearity evaluation.</a> J. Chromatogr. B. 877, 2224-2234 (2009).</li></ol>

In order to achieve optimum measurement of H2S, this method employs a Deans switch, backflushing and a sulfur chemiluminescence detector (SCD). A dimethylpolysiloxane column is used as the first dimension GC column, and serves to retard the movement of heavier hydrocarbons present in the sample so that they do not contaminate the PLOT column. This effect is enhanced by a cool (50 &#176;C) initial separation. Light gases pass through the first dimension column and are captured by the PLOT column during the hear...

Accurate analysis of crude oil is essential for the oil and gas industry, as health and safety regulations and economics are functions of oil quality. In order to protect transporters of crude samples, it is necessary to determine the properties of crude samples to develop safety regulations to be implemented in the event of a release or spill. In particular, quantification of hydrogen sulfide (H2S) is important, due to its high toxicity in the gas phase; exposures as low as 100 ppm can be fatal (http://www.cdc.gov/niosh/idlh/7783064.html)1,2. Dissolved H2S in crude samples is generally considered to be corrosive3,4, and can deactivate catalysts used to treat the oil5-7. Removal of H2S from crude oil streams is ideal, but without a method to measure dissolved H2S, it is difficult to assess the success of removal treatments. For these reasons, this protocol was developed to measure dissolved H2S in heavy crude oil samples such as Canadian oil sands crudes.
A number of standard methods exist for quantification of H2S in lighter petroleum or fuel based samples, but none have been validated for use with the heavier crudes commonly extracted from the Canadian oil sands. H2S and mercaptans are determined using a titration technique by Universal Oil Products (UOP) method 1638, but this method suffers from user-interpretation bias that results from manual reading of titration curves. Institute of Petroleum (IP) method 570 uses a specialty H2S analyzer that heats fuel oil samples9, and benefits from simplicity and portability, but lacks accuracy with heavier samples10. The American Society for Testing and Materials (ASTM) method D5623 uses gas chromatography (GC) with cryogenic cooling and sulfur selective detection to measure H2S in light petroleum liquids11,12. This standard could be improved to use an ambient separation and also be applied to heavier crude oils, therefore it was used as the basis for the protocol discussed herein.
GC is a heavily used technique for the analysis of petroleum samples. Samples are vaporized in a hot inlet, and separations occur in the gas phase. The gas phase separation makes GC ideal for the analysis of H2S, as it is easily liberated from the liquid sample during heating in the inlet. GC methods can be created and tailored for different samples, depending on the temperature programs used, columns implemented, and the use of multidimensional chromatography13-15. There have been a number of recent developments for the measurement of H2S using GC. Luong et al. demonstrated H2S and other light sulfur compound measurement in light and middle distillates using multidimensional GC and Deans switching, but the method has not yet been applied to heavier crudes16. Di Sanzo et al. also quantified H2S in gasoline using GC, however it also has not been used on heavier crudes, and requires sub-ambient cooling17. The method presented here demonstrates considerable time saving over these previous methods, with a completed analysis time of 5 min, compared to 10 min&#160;(Luong) and 40 min&#160;(Di Sanzo). Unfortunately, implementation of these methods in our lab to compare accuracy was not possible due to equipment and time restrictions.
Multidimensional GC allows the user to exploit the selectivity of two columns, rather than a single column. In conventional GC, separation occurs on one column. In the case of multidimensional GC, the sample is separated on two different columns, enhancing the separation and selectivity. The Deans switch is one device used to employ a two-dimensional column configuration. The switch uses an external valve to direct gas flow from an inlet on the switch to one of two outlet ports18-20. Effluent from the first column can be directed in either direction; in this case, light sulfur gases are &#8220;heart cut&#8221;21 from the first separation to a porous layer open tubular (PLOT) column for secondary separation, which has been shown to be excellent for the separation of H2S from other light sulfur gases (http://www.chem.agilent.com/cag/cabu/pdf/gaspro.pdf)22-24. A sulfur chemiluminescence detector is used for detection, providing selectivity for sulfur compounds and eliminating possible interference from any other light gases that may have been transferred to the PLOT column during the heart cut. Hydrocarbons from the crude oil sample are retained on the first dimension column and are removed during a backflush procedure; this protects the PLOT column from any contamination25-27. This approach has also been successfully implemented for the analysis of oxidation inhibitors in transformer oils28.
Herein, a two-dimensional GC method is employed for the analysis and quantification of dissolved H2S in heavy crude oil samples. The method is shown to be applicable over a wide range of H2S concentrations, and can also be used to measure H2S in gas phase samples.

<table border="0" cellpadding="0" cellspacing="0" width="700">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Deans switch</td>
			<td style="width:199px;">Agilent</td>
			<td style="width:119px;">G2855A</td>
			<td style="width:167px;">Or equivalent flow switching device</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Restrictor tubing&#160;</td>
			<td style="width:199px;">Agilent</td>
			<td style="width:119px;">160-2615-10</td>
			<td style="width:167px;">Fused silica, deactivated, 180 &#181;m</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">HP-PONA column</td>
			<td style="width:199px;">Agilent</td>
			<td style="width:119px;">19091S-001</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">GasPro column</td>
			<td style="width:199px;">Agilent</td>
			<td style="width:119px;">113-4332</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Sulfur chemiluminescence detector, 355</td>
			<td style="width:199px;">Agilent/Sievers</td>
			<td style="width:119px;">G6603A</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:216px;">H2S calibration standard, in He</td>
			<td style="width:199px;">Air Liquide</td>
			<td style="width:119px;">Custom order</td>
			<td style="width:167px;">211 ppm H2S</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:216px;">CS2</td>
			<td style="width:199px;">Fisher Scientific</td>
			<td style="width:119px;">C184-500</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Toluene, HPLC grade</td>
			<td style="width:199px;">Fisher Scientific</td>
			<td style="width:119px;">T290-4</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Gas bag, 2 L</td>
			<td style="width:199px;">Calibrated Instruments, Inc.</td>
			<td style="width:119px;">GSB-P/2</td>
			<td style="width:167px;">Twist on/off nozzle</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">250 &#181;L gas tight syringe</td>
			<td style="width:199px;">Hamilton</td>
			<td style="width:119px;">81130</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">500 mL amber glass bottle</td>
			<td style="width:199px;">Scientific Specialties</td>
			<td style="width:119px;">N73616</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Open top screw caps</td>
			<td style="width:199px;">Scientific Specialties</td>
			<td style="width:119px;">169628</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Tegrabond disc for screw caps</td>
			<td style="width:199px;">Chromatographic Specialties</td>
			<td style="width:119px;">C889125C</td>
			<td style="width:167px;">25 mm, 10/90 MIL</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">1 mL gas tight syringe</td>
			<td style="width:199px;">Hamilton</td>
			<td style="width:119px;">81330</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:216px;">2.5% H2S in He gas standard</td>
			<td style="width:199px;">Air Liquide</td>
			<td style="width:119px;">Custom order</td>
			<td style="width:167px;"></td>
		</tr>
	</tbody>
</table>

measurement of h2s in crude oil and crude oil headspace using multidimensional gas chromatography, deans switching and sulfur-selective detection

A method for the analysis of dissolved hydrogen sulfide in crude oil samples is demonstrated using gas chromatography. In order to effectively eliminate interferences, a two dimensional column configuration is used, with a Deans switch employed to transfer hydrogen sulfide from the first to the second column (heart-cutting). Liquid crude samples are first separated on a dimethylpolysiloxane column, and light gases are heart-cut and further separated on a bonded porous layer open tubular (PLOT) column that is able to separate hydrogen sulfide from other light sulfur species. Hydrogen sulfide is then detected with a sulfur chemiluminescence detector, adding an additional layer of selectivity. Following separation and detection of hydrogen sulfide, the system is backflushed to remove the high-boiling hydrocarbons present in the crude samples and to preserve chromatographic integrity. Dissolved hydrogen sulfide has been quantified in liquid samples from 1.1 to 500 ppm, demonstrating wide applicability to a range of samples. The method has also been successfully applied for the analysis of gas samples from crude oil headspace and process gas bags, with measurement from 0.7 to 9,700 ppm hydrogen sulfide.

In order to obtain reliable quantification of H2S for both liquid and gas samples, proper calibration is necessary. For calibration injections and sample injections, the H2S peak should not be overlapping with neighboring peaks and should have a reproducible peak area. Figure 3 shows an injection of a gas sample where the gas is too concentrated for this method. It was found that gas concentrations of greater than 500 ppm using a 250 &#181;l syringe overloaded the detector. This iss...

Watch this Scientific Journal Video about Measurement of H2S in Crude Oil and Crude Oil Headspace Using Multidimensional Gas Chromatography, Deans Switching and Sulfur-selective Detection at JoVE.com

Measurement of H2S in Crude Oil and Crude Oil Headspace Using Multidimensional Gas Chromatography, Deans Switching and Sulfur-selective Detection

A multidimensional gas chromatography method for the analysis of dissolved hydrogen sulfide in liquid crude oil samples is presented. A Deans switch is used to heart-cut light sulfur gases for separation on a secondary column and detection on a sulfur chemiluminescence detector.

Measurement of H2S in Crude Oil and Crude Oil Headspace Using Multidimensional Gas Chromatography, Deans Switching and Sulfur-selective Detection

A method for the analysis of dissolved hydrogen sulfide in crude oil samples is demonstrated using gas chromatography. In order to effectively eliminate ...

measurement-h2s-crude-oil-crude-oil-headspace-using-multidimensional

Research

JoVE Journal

Environment

18.9K ビュー.  Natural Resources Canada. A multidimensional gas chromatography method for the analysis of dissolved hydrogen sulfide in liquid crude oil samples is presented. A Deans switch is used to heart-cut light sulfur gases for separation on a secondary column and detection on a sulfur chemiluminescence detector. 

ビデオ: Measurement of H2S in Crude Oil and Crude Oil Headspace Using Multidimensional Gas Chromatography, Deans Switching and Sulfur-selective Detection

Optimize Flue Gas Settings to Promote Microalgae Growth in Photobioreactors via Computer Simulations

Flue gas from power plants can promote algal cultivation and reduce greenhouse gas emissions1. Microalgae not only capture solar energy more efficiently than plants3, but also synthesize advanced biofuels2-4. Generally, atmospheric CO2 is not a sufficient source for supporting maximal algal growth5. On the other hand, the high concentrations of CO2 in industrial exhaust gases have adverse effects on algal physiology. Consequently, both cultivation conditions (such as nutrients and light) and the control of the flue gas flow into the photo-bioreactors are important to develop an efficient &ldquo;flue gas to algae&rdquo; system. Researchers have proposed different photobioreactor configurations4,6 and cultivation strategies7,8 with flue gas. Here, we present a protocol that demonstrates how to use models to predict the microalgal growth in response to flue gas settings. We perform both experimental illustration and model simulations to determine the favorable conditions for algal growth with flue gas. We develop a Monod-based model coupled with mass transfer and light intensity equations to simulate the microalgal growth in a homogenous photo-bioreactor. The model simulation compares algal growth and flue gas consumptions under different flue-gas settings. The model illustrates: 1) how algal growth is influenced by different volumetric mass transfer coefficients of CO2; 2) how we can find optimal CO2 concentration for algal growth via the dynamic optimization approach (DOA); 3) how we can design a rectangular on-off flue gas pulse to promote algal biomass growth and to reduce the usage of flue gas. On the experimental side, we present a protocol for growing Chlorella under the flue gas (generated by natural gas combustion). The experimental results qualitatively validate the model predictions that the high frequency flue gas pulses can significantly improve algal cultivation.

Flue gas from power plants is a cheap CO2 source for algal growth. We have built prototype &#34;flue gas to algal cultivation&#34; systems and described how to scale up the algal cultivation process. We have demonstrated the use of a mass-transfer bio-reaction model to simulate and to design the optimal operation of flue gas for the growth of Chlorella sp. in algal photo-bioreactors.

Flue gas from power plants can promote algal cultivation and reduce greenhouse gas emissions1. Microalgae not only capture solar energy more efficiently ...

Measurement of Greenhouse Gas Flux from Agricultural Soils Using Static Chambers

Measurement of greenhouse gas (GHG) fluxes between the soil and the atmosphere, in both managed and unmanaged ecosystems, is critical to understanding the biogeochemical drivers of climate change and to the development and evaluation of GHG mitigation strategies based on modulation of landscape management practices. The static chamber-based method described here is based on trapping gases emitted from the soil surface within a chamber and collecting samples from the chamber headspace at regular intervals for analysis by gas chromatography. Change in gas concentration over time is used to calculate flux. This method can be utilized to measure landscape-based flux of carbon dioxide, nitrous oxide, and methane, and to estimate differences between treatments or explore system dynamics over seasons or years. Infrastructure requirements are modest, but a comprehensive experimental design is essential. This method is easily deployed in the field, conforms to established guidelines, and produces data suitable to large-scale GHG emissions studies.

This article showcases the static chamber-based method for measurement of greenhouse gas flux from soil systems. With relatively modest infrastructure investments, measurements may be obtained from multiple treatments/locations and over timeframes ranging from hours to years.

Measurement of greenhouse gas (GHG) fluxes between the soil and the atmosphere, in both managed and unmanaged ecosystems, is critical to understanding the ...

EPA Method 1615. Measurement of Enterovirus and Norovirus Occurrence in Water by Culture and RT-qPCR. Part III. Virus Detection by RT-qPCR

EPA Method 1615 measures enteroviruses and noroviruses present in environmental and drinking waters. This method was developed with the goal of having a standardized method for use in multiple analytical laboratories during monitoring period 3 of the Unregulated Contaminant Monitoring Rule. Herein we present the protocol for extraction of viral ribonucleic acid (RNA) from water sample concentrates and for quantitatively measuring enterovirus and norovirus concentrations using reverse transcription-quantitative PCR (RT-qPCR). Virus concentrations for the molecular assay are calculated in terms of genomic copies of viral RNA per liter based upon a standard curve. The method uses a number of quality controls to increase data quality and to reduce interlaboratory and intralaboratory variation. The method has been evaluated by examining virus recovery from ground and reagent grade waters seeded with poliovirus type 3 and murine norovirus as a surrogate for human noroviruses. Mean poliovirus recoveries were 20% in groundwaters and 44% in reagent grade water. Mean murine norovirus recoveries with the RT-qPCR assay were 30% in groundwaters and 4% in reagent grade water.

Here we present a procedure to quantify enterovirus and norovirus in environmental and drinking waters using reverse transcription-quantitative PCR. Mean virus recovery from groundwater with this standardized procedure from EPA Method 1615 was 20% for poliovirus and 30% for murine norovirus.

EPA Method 1615 measures enteroviruses and noroviruses present in environmental and drinking waters. This method was developed with the goal of having a ...

Chemical Analysis of Water-accommodated Fractions of Crude Oil Spills Using TIMS-FT-ICR MS

Multiple chemical processes control how crude oil is incorporated into seawater and also the chemical reactions that occur overtime. Studying this system requires the careful preparation of the sample in order to accurately replicate the natural formation of the water-accommodated fraction that occurs in nature. Low-energy water-accommodated fractions (LEWAF) are carefully prepared by mixing crude oil and water at a set ratio. Aspirator bottles are then irradiated, and at set time points, the water is sampled and extracted using standard techniques. A second challenge is the representative characterization of the sample, which must take into consideration the chemical changes that occur over time. A targeted analysis of the aromatic fraction of the LEWAF can be performed using an atmospheric-pressure laser ionization source coupled to a custom-built trapped ion mobility spectrometry&#8211;Fourier transform&#8211;ion cyclotron resonance mass spectrometer (TIMS-FT-ICR MS). The TIMS-FT-ICR MS analysis provides high-resolution ion mobility and ultrahigh-resolution MS analysis, which further allow the identification of isomeric components by their collision cross-sections (CCS) and chemical formula. Results show that as the oil-water mixture is exposed to light, there is significant photo-solubilization of the surface oil into the water. Over time, the chemical transformation of the solubilized molecules takes place, with a decrease in the number of identifications of nitrogen- and sulfur-bearing species in favor of those with a greater oxygen content than were typically observed in the base oil.

The low-energy water-accommodated fraction (LEWAF) of crude oil is a challenging system to analyze, because over time, this complex mixture undergoes chemical transformations. This protocol illustrates methods for the preparation of the LEWAF sample and for performing photo-irradiation and chemical analysis by trapped ion mobility spectrometry&#8211;FT-ICR MS.

Multiple chemical processes control how crude oil is incorporated into seawater and also the chemical reactions that occur overtime. Studying this system ...

Measurement of the Rheology of Crude Oil in Equilibrium with CO2 at Reservoir Conditions

A rheometer system to measure the rheology of crude oil in equilibrium with carbon dioxide (CO2) at high temperatures and pressures is described. The system comprises a high-pressure rheometer which is connected to a circulation loop. The rheometer has a rotational flow-through measurement cell with two alternative geometries: coaxial cylinder and double gap. The circulation loop contains a mixer, to bring the crude oil sample into equilibrium with CO2, and a gear pump that transports the mixture from the mixer to the rheometer and recycles it back to the mixer. The CO2 and crude oil are brought to equilibrium by stirring and circulation and the rheology of the saturated mixture is measured by the rheometer. The system is used to measure the rheological properties of Zuata crude oil (and its toluene dilution) in equilibrium with CO2 at elevated pressures up to 220 bar and a temperature of 50 &#176;C. The results show that CO2 addition changes the oil rheology significantly, initially reducing the viscosity as the CO2 pressure is increased and then increasing the viscosity above a threshold pressure. The non-Newtonian response of the crude is also seen to change with the addition of CO2.

Measurement of the Rheology of Crude Oil in Equilibrium with CO2 at Reservoir Conditions

A method for measuring the rheology of crude oil in equilibrium with carbon dioxide at reservoir conditions is presented.

A rheometer system to measure the rheology of crude oil in equilibrium with carbon dioxide (CO2) at high temperatures and pressures is described. The ...

Microfluidic Devices for Characterizing Pore-scale Event Processes in Porous Media for Oil Recovery Applications

Microfluidic devices are versatile tools for studying transport processes at a microscopic scale. A demand exists for microfluidic devices that are resistant to low molecular-weight oil components, unlike traditional polydimethylsiloxane (PDMS) devices. Here, we demonstrate a facile method for making a device with this property, and we use the product of this protocol for examining the pore-scale mechanisms by which foam recovers crude oil. A pattern is first designed using computer-aided design (CAD) software and printed on a transparency with a high-resolution printer. This pattern is then transferred to a photoresist via a lithography procedure. PDMS is cast on the pattern, cured in an oven, and removed to obtain a mold. A thiol-ene crosslinking polymer, commonly used as an optical adhesive (OA), is then poured onto the mold and cured under UV light. The PDMS mold is peeled away from the optical adhesive cast. A glass substrate is then prepared, and the two halves of the device are bonded together. Optical adhesive-based devices are more robust than traditional PDMS microfluidic devices. The epoxy structure is resistant to swelling by many organic solvents, which opens new possibilities for experiments involving light organic liquids. Additionally, the surface wettability behavior of these devices is more stable than that of PDMS. The construction of optical adhesive microfluidic devices is simple, yet requires incrementally more effort than the making of PDMS-based devices. Also, though optical adhesive devices are stable in organic liquids, they may exhibit reduced bond-strength after a long time. Optical adhesive microfluidic devices can be made in geometries that act as 2-D micromodels for porous media. These devices are applied in the study of oil displacement to improve our understanding of the pore-scale mechanisms involved in enhanced oil recovery and aquifer remediation.

The goal of this procedure is to easily and rapidly produce a microfluidic device with customizable geometry and resistance to swelling by organic fluids for oil recovery studies. A polydimethylsiloxane mold is first generated, and then used to cast the epoxy-based device. A representative displacement study is reported.

Microfluidic devices are versatile tools for studying transport processes at a microscopic scale. A demand exists for microfluidic devices that are ...

Assessment of Methane and Nitrous Oxide Fluxes from Paddy Field by Means of Static Closed Chambers Maintaining Plants Within Headspace

This protocol describes the measurement of greenhouse gas (GHG) emissions from paddy soils using the static closed chamber technique. This method is based on the diffusion theory. A known volume of air overlaying a defined soil area is enclosed within a parallelepiped cover (named &#34;chamber&#34;), for a defined period of time. During this enclosure period, gases (methane (CH4) and nitrous oxide (N2O)) move from soil pore air near their microbial source (i.e., methanogens, nitrifiers, denitrifiers) to the chamber headspace, following a natural concentration gradient. Fluxes are then estimated from chamber headspace concentration variations sampled at regular intervals throughout the enclosure and then analyzed with gas chromatography. Among the techniques available for GHG measurement, the static closed chamber method is suitable for plot experiments, as it does not require large homogenously treated soil areas. Furthermore, it is manageable with limited resources and can identify relationships among ecosystem properties, processes, and fluxes, especially when combined with GHG driving force measurements. Nevertheless, with respect to the micrometeorological method, it causes a minimal but still unavoidable soil disturbance, and allows a minor temporal resolution. Several phases are key to the method implementation: i) chamber design and deployment, ii) sample handling and analyses, and iii) flux estimation. Technique implementation success in paddy fields demands adjustments for field flooding during much of the cropping cycle, and for rice plant maintenance within the chamber headspace during measurements. Therefore, the additional elements to be considered with respect to the usual application of non-flooded agricultural soils consist of devices for: i) avoiding any unintended water disturbance that could overestimate fluxes, and ii) including rice plants within the chamber headspace to fully consider gases emitted through aerenchyma transportation.

The overall goal of this protocol is to measure greenhouse gas emissions from paddy fields using the static closed chamber technique. The measurement system needs specific adjustments due to the presence of both a permanent water layer in the field and of the plants within the chamber headspace.

This protocol describes the measurement of greenhouse gas (GHG) emissions from paddy soils using the static closed chamber technique. This method is based ...

The Effect of the Application of Thyme Essential Oil on Microbial Load During Meat Drying

Meat is a high protein meal that is used in the preparation of jerky, a popular food snack, where preservation and safety are important. To assure food safety and to extend the shelf life of meat and meat products, the use of either synthetic or natural preservatives have been applied to control and eliminate foodborne bacteria. A growing interest in the application of natural food additives for meat has increased. Microorganisms, such as Escherichia coli, contaminate meat and meat products, causing foodborne illnesses. Therefore, it is necessary to improve the meat conservation process. However, the use of essential oils when the meat is being dried has not been deeply studied. In this regard, there is an opportunity to increase the value of dried meat and reduce the risk of foodborne illnesses by applying essential oils during the drying process. In this protocol, we present a novel method of applying thyme essential oil (TEO) during meat drying, specifically in vapor form directly in a drying chamber. For evaluation, we use Minimal Inhibitory Concentration (MIC) to detect the number of harmful bacteria in the treated samples compared to raw samples. The preliminary results show that this method is a viable and alternative option to synthetic preservatives and that it significantly reduces microbial load in dried meat.

Microorganisms such as Escherichia coli that contaminate meat products cause foodborne illnesses. The use of essential oils in the meat drying process has not been deeply studied. Here, we present a novel method of applying thyme essential oil to meat during drying to reduce the microbial load in dried meat.

Meat is a high protein meal that is used in the preparation of jerky, a popular food snack, where preservation and safety are important. To assure food ...

Experimental Study of the Relationship Between Particle Size and Methane Sorption Capacity in Shale

The amount of adsorbed shale gas is a key parameter used in shale gas resource evaluation and target area selection, and it is also an important standard for evaluating the mining value of shale gas. Currently, studies on the correlation between particle size and methane adsorption are controversial. In this study, an isothermal adsorption apparatus, the gravimetric sorption analyzer, is used to test the adsorption capacity of different particle sizes in shale to determine the relationship between the particle size and the adsorption capacity of shale. Thegravimetric method requires fewer parameters and produces better results in terms of accuracy and consistency than methods like the volumetric method. Gravimetric measurements are performed in four steps: a blank measurement, preprocessing, a buoyancy measurement, and adsorption and desorption measurements. Gravimetric measurement is presently considered to be a more scientific and accurate method of measuring the amount of adsorption; however, it is time-consuming and requires a strict measuring technique. A Magnetic Suspension Balance (MSB) is the key to verify the accuracy and consistency of this method. Our results show that adsorption capacity and particle size are correlated, but not a linear correlation, and the adsorptions in particles sieved into 40 - 60 and 60 - 80 meshes tend to be larger. We propose that the maximum adsorption corresponding to the particle size is approximately 250 &#181;m (60 mesh) in the shale gas fracturing.

We use an isothermal adsorption apparatus, the gravimetric sorption analyzer, to test the adsorption capacity of different particle sizes of shale, in order to find out the relationship between particle size and the adsorption capacity of shale.

The amount of adsorbed shale gas is a key parameter used in shale gas resource evaluation and target area selection, and it is also an important standard ...

Detection of Viruses from Bioaerosols Using Anion Exchange Resin

This protocol demonstrates a customized bioaerosol sampling method for viruses. In this system, anion exchange resin is coupled with liquid impingement-based air sampling devices for efficacious concentration of negatively-charged viruses from bioaerosols. Thus, the resin serves as an additional concentration step in the bioaerosol sampling workflow. Nucleic acid extraction of the viral particles is then performed directly from the anion exchange resin, with the resulting sample suitable for molecular analyses. Further, this protocol describes a custom-built bioaerosol chamber capable of generating virus-laden bioaerosols under a variety of environmental conditions and allowing for continuous monitoring of environmental variables such as temperature, humidity, wind speed, and aerosol mass concentration. The main advantage of using this protocol is increased sensitivity of viral detection, as assessed via direct comparison to an unmodified conventional liquid impinger. Other advantages include the potential to concentrate diverse negatively-charged viruses, the low cost of anion exchange resin (~$0.14 per sample), and ease of use. Disadvantages include the inability of this protocol to assess infectivity of resin-adsorbed viral particles, and potentially the need for the optimization of the liquid sampling buffer used within the impinger.

An anion exchange resin-based method, adapted to liquid impingement-based bioaerosol sampling of viruses is demonstrated. When coupled with downstream molecular detection, the method allows for facile and sensitive detection of viruses from bioaerosols.