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 crude samples should be opened, transferred and handled in a fumehood. Certified gas standards will be delivered from the manufacturer with an expiry date, and for the most accurate results care should be taken to use standards that have not expired.
1. Preparation of Standards
<ol>
	<li>Liquid standards
	<ol>
		<li>Using an automatic pipette, dispense 10 &#181;l of carbon disulfide (CS2) into a 50 ml volumetric flask. Fill the volumetric flask to the marked line with HPLC (high performance liquid chromatography) grade toluene. Cap the flask and mix the solution by inverting and swirling a minimum of five times; this is the 500 ppm stock calibration solution.</li>
		<li>On each day of analysis, prepare four vials of CS2 for calibration. Label four 1.5 ml autosampler vials and place them in a vial tray.</li>
		<li>Using an automatic pipette, dispense 200 &#181;l of the 500 ppm stock CS2 solution into each vial. Using a second automatic pipette, dispense 800 &#181;l of HPLC grade toluene into each of the four vials. Cap each vial immediately after dispensing the CS2 and toluene, and invert three times to mix; these are the 100 ppm calibration standards.</li>
	</ol>
	</li>
	<li>Gas standards
	<ol>
		<li>Move a gas cylinder of certified calibration gas to a vented fumehood, and attach a regulator that is fitted for attachment to a gas bag.</li>
		<li>Open the nozzle on an empty gas bag and attach the gas bag to the regulator on the gas cylinder.</li>
		<li>With the regulator closed, open the gas cylinder by turning the knob on top counterclockwise.</li>
		<li>Turn the knob on the regulator counterclockwise until a steady flow of gas fills the gas bag. When the gas bag is full, turn the regulator knob clockwise to shut off the gas flow.</li>
		<li>Close the nozzle on the gas bag and detach it from the regulator. Close the gas cylinder by turning the knob on top clockwise. Open the regulator to purge any remaining gas and release pressure, closing it again when the regulator no longer has any gas it in it.</li>
	</ol>
	</li>
</ol>
2. Instrument Set-up
<ol>
	<li>Method parameters
	<ol>
		<li>Using the following procedure, configure the Deans switch according to the columns installed in the gas chromatograph, as each system will have unique pressure settings.</li>
		<li>Open a Deans switch calculator program on a computer, and input the column dimensions, carrier gas, temperature, desired flow rates and detectors used (see Figure 1).The calculator will define the pressures needed for the inlet and pressure control module (PCM), and the length of restrictor tubing needed for installation between the Deans switch and the flame ionization detector (FID). Note these pressures and input them into the method file.</li>
		<li>Using the information from the Deans switch calculator and the information in Table 1, program the method file with the correct parameters for either gas or liquid analysis. Save the method file.</li>
	</ol>
	</li>
</ol>
<img alt="Figure 1" src="/files/ftp_upload/53416/53416fig1.jpg" /> 
Figure 1. Deans switch calculator. Screenshot of the Deans switch calculator program. User-adjustable parameters are shown in white boxes, and output parameters are shown in blue boxes. <a href="https://www.jove.com/files/ftp_upload/53416/53416fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<ol start="2">
	<li>Column installation
	<ol>
		<li>Ensure that the instrument, oven and inlet are at RT. Turn off the gas flow to the inlet and PCM supplying flow to the Deans switch.</li>
		<li>Following the manufacturer&#39;s instructions, install the dimethylpolysiloxane column between the split/splitless inlet and the Deans switch, the PLOT column between the Deans switch and the sulfur chemiluminescence detector (SCD), and the restrictor tubing (length determined in step 2.1.2) between the Deans switch and the FID.</li>
		<li>Using the gas chromatograph software, turn on the carrier gas flow to the inlet and PCM, and test the system for leaks by passing an electronic leak detector in close proximity of the fittings at the end of each column and at the Deans switch; leaks are indicated by a light and/or sound notification on the detector.
		<ol>
			<li>If leaks are present, gently tighten fittings and re-test with the electronic leak detector. Close the oven door and turn on the gas chromatograph oven and inlet heater.</li>
		</ol>
		</li>
		<li>Perform a bake-out of the columns and restrictor tubing by increasing the oven temperature to the upper temperature limit of the PLOT column (found on the column documentation); allow the oven to sit at this temperature for a minimum of 3 hr.</li>
		<li>When the bake-out is complete, cool the oven to RT and re-test the connections inside the oven for gas leaks with the electronic leak detector, tightening where necessary.</li>
		<li>Load the pre-programmed method file using the software controlling the gas chromatograph; the instrument is ready for analysis.</li>
	</ol>
	</li>
</ol>
<img alt="Figure 2" src="/files/ftp_upload/53416/53416fig2.jpg" /> 
Figure 2. Gas chromatograph oven. Configuration of the column arrangement in the GC oven. FID: flame ionization detector, SCD: sulfur chemiluminescence detector. <a href="https://www.jove.com/files/ftp_upload/53416/53416fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<ol start="3" style="margin-left: 0px;">
	<li>Determining proper Deans switch timing
	<ol>
		<li>As the Deans switch is controlled by a valve in the gas chromatograph; locate the valve timing point section in the method parameters. In the software, set the switch to &#34;on&#34;, and create time events for the valve that controls the Deans switch, beginning with the valve turning &#34;off&#34; at 0.5 min, and a second event that turns the valve &#34;on&#34; again at 3.0 min. The &#34;off&#34; position in this description corresponds to the direction in which column effluent will be carried to the SCD.</li>
		<li>Place a gas bag containing the calibration gas (known amount of H2S in helium) in the fumehood, and place a rubber nipple or equivalent penetrable cover on the nozzle of the gas bag. Open the nozzle on the gas bag.</li>
		<li>Using a 250 &#181;l gas-tight glass syringe, puncture the rubber nipple on the top of the bag and withdraw 250 &#181;l of calibration gas. Cap the syringe with an inlet septa, and transport the syringe to the gas chromatograph.</li>
		<li>Remove the septa cap from the syringe; manually and swiftly inject the calibration gas into the gas chromatograph, simultaneously starting the software acquisition. The H2S will appear as a peak on the SCD signal trace; record the retention time of this peak. .</li>
		<li>Begin decreasing the time of the heart-cut window, one side at a time (i.e., decrease the valve &#34;on&#34; event by 0.1 min for sequential injections); continue in this manner until the H2S peak disappears from the chromatogram. Add 0.2 min to this time and note it as the upper limit of the heart-cut window.</li>
		<li>Perform the same procedure on the lower end of the time window, gradually increasing the time of the valve &#34;off&#34; event for sequential injections until the peaks are no longer visible. Subtract 0.2 min from this time and note it as the lower limit of the heart-cut window.</li>
		<li>Save the valve &#34;on&#34;/&#34;off&#34; commands into the method file.</li>
	</ol>
	</li>
</ol>
3. Instrument Calibration
<ol>
	<li>Liquid
	<ol>
		<li>Ensure that a liquid autosampler is installed on the split/splitless inlet of the gas chromatograph. Place the four previously prepared calibration vials in vial positions 1-4 on the autosampler tray.</li>
		<li>Using a glass pipette, fill a vial with HPLC grade toluene and place it in the vial position for the wash solvent on the autosampler tray. Ensure that the waste vial or reservoir on the autosampler tray is empty.</li>
		<li>Load the method configured for liquid phase analysis on the software connected to the gas chromatograph; ensure that both detectors are turned on and that the gas chromatograph is in a ready state.</li>
		<li>Use the gas chromatograph software to perform one injection per vial according to the method, and integrate the CS2 peak in each chromatogram using the software provided with the gas chromatograph.</li>
		<li>Using a spreadsheet program, calculate an average response factor for the SCD by dividing the area counts of the CS2 peak by the concentration of the calibration solution (100 ppm), and then dividing this by two to give response per one atom of sulfur.</li>
	</ol>
	</li>
	<li>Gas
	<ol>
		<li>Ensure that the liquid autosampler tower has been removed from the gas chromatograph, and load the appropriate method for gas analysis. Ensure that both detectors are turned on, and that the gas chromatograph is in a ready state.</li>
		<li>Inject the calibration gas as described in steps 2.3.2 to 2.3.4.</li>
		<li>Repeat the manual injection of calibration gas a minimum of three times.</li>
		<li>Use the gas chromatograph data analysis software to integrate the H2S peaks in the three injections and, using a spreadsheet program, calculate an average response factor for H2S by dividing the average area of the H2S peaks by the concentration of H2S in the gas bag.</li>
	</ol>
	</li>
</ol>
4. Sample Analysis
<ol>
	<li>Liquid
	<ol>
		<li>Assess crudes for injection by transferring a small amount (&#60;1 ml) with a glass pipette. If the crude is transferred with no significant residue left in the glass pipette, the crude can be injected neat. If the crude leaves a significant amount in the glass pipette, dilute as described in 4.1.2. For crudes that can be injected neat, transfer ~1 ml of the crude into a gas chromatograph autosampler vial, and cap the vial.</li>
		<li>Dilute high viscosity crudes by transferring 0.75 ml of crude with an automatic pipette to an autosampler vial, and adding an equal volume of HPLC grade toluene. Cap and invert the vial with shaking to adequately mix the solution.</li>
		<li>Place the filled vials in the autosampler tray, and load the liquid analysis method on the gas chromatograph software.</li>
		<li>Using the gas chromatograph software and the previously configured method (Table 1), use the automatic sampler to perform three replicate injections per vial.</li>
	</ol>
	</li>
	<li>Gas
	<ol>
		<li>Headspace
		<ol>
			<li>Fill a 500 ml amber glass bottle with 450 ml of the crude to be analyzed. Attach a septum-topped cap to the top of the bottle. Perform any crude transfer steps in a vented fumehood.</li>
			<li>Place the bottle(s) to be analyzed in a temperature controlled environment (i.e., a water bath at 30 &#176;C). Note: Crude oil samples may become volatile at elevated temperatures and care should be exercised depending on the samples used.</li>
			<li>Using a 1 ml glass gas tight syringe, puncture the septum top and leave the syringe in the top of the bottle to provide an avenue for pressure release if the gas in the headspace should build up.</li>
			<li>Leave the bottle(s) in the temperature controlled environment for 24 hr, gently lifting and shaking the bottles once an h to equilibrate the H2S between the liquid and headspace.</li>
			<li>To analyze the headspace gas, puncture the septum top and withdraw &#181;l of gas into a gas tight glass syringe.</li>
			<li>Cap the syringe end with a piece of inlet septa and transport the syringe to the gas chromatograph. Manually and swiftly inject the gas into the inlet, simultaneously starting the software to begin data collection.</li>
			<li>Repeat this procedure to obtain a minimum of three replicate injections of gas. If the H2S peak is too concentrated and not on the scale of the detector (see Figure 3), perform the procedure with a smaller syringe of gas to bring the peak on scale; i.e., 100 &#181;l or 25 &#181;l.</li>
		</ol>
		</li>
		<li>Gas bags
		<ol>
			<li>Place a rubber nipple or equivalent penetrable cover on the nozzle of the gas bag to be analyzed, and place the gas bag in a vented fumehood.</li>
			<li>Ensure the correct method for gas analysis is loaded on the gas chromatograph software, and that the gas chromatograph is in the ready state.</li>
			<li>Open the nozzle on the gas bag, and puncture the top of the nipple with a 250 &#181;l gas tight syringe. Fill the syringe with 250 &#181;l of gas, withdraw the syringe, and close the nozzle on the gas bag.</li>
			<li>Cap the syringe end with a piece of inlet septa and transport the syringe to the gas chromatograph, and manually inject the gas into the inlet, simultaneously starting the software to begin data collection.</li>
			<li>Repeat this procedure to obtain a minimum of three replicate injections of gas. If the H2S peak is too concentrated and is not on the scale of the detector (see Figure 3), perform the procedure with a smaller syringe of gas to bring the peak on scale; i.e., 100 &#181;l or 25 &#181;l.</li>
		</ol>
		</li>
	</ol>
	</li>
</ol>
<img alt="Figure 3" src="/files/ftp_upload/53416/53416fig3.jpg" /> 
Figure 3. A gas chromatogram with an overloaded H2S peak. A gas injection from the headspace of a liquid crude sample held at 30 &#176;C, demonstrating an overloading of the SCD. <a href="https://www.jove.com/files/ftp_upload/53416/53416fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
5. Data Analysis
<ol>
	<li>Liquid
	<ol>
		<li>Determining H2S peak retention time (only needs to be repeated if instrument configuration changes)
		<ol>
			<li>Use a glass pipette to fill a GC autosampler vial with a liquid crude that does not require dilution and cap the vial.</li>
			<li>Load the appropriate method for liquid analysis on the gas chromatograph software, and ensure the liquid autosampler tower is installed.</li>
			<li>Place the liquid crude sample in the autosampler tray, and perform one injection of the crude.</li>
			<li>Fill a glass gas-tight syringe with 750 &#181;l of H2S-containing gas (2.5% in helium). Remove the vial from the autosampler tray and puncture the septa on the cap of the vial with the syringe filled with gas, and place the end of the syringe below the surface of the sample in the vial. Depress the plunger on the syringe to bubble the gas through the crude sample.</li>
			<li>Place the vial back in the autosampler tray and use the software to direct the autosampler to perform a single injection of the spiked sample.</li>
			<li>Using the software accompanying the gas chromatograph, compare the chromatograms before and after the H2S spike. A large peak should be present in the second chromatogram that was not present in the first chromatogram; record the retention time of this peak (see Figure 4).</li>
		</ol>
		</li>
		<li>Analysis
		<ol>
			<li>Use the data analysis software accompanying the gas chromatograph to integrate the peak area for H2S (identify using the retention time noted in step 5.1.1.6) in each chromatogram (Figure 5), and calculate the average peak area for each sample with a spreadsheet program.</li>
			<li>Using the response factor determined in Section 3.1, divide the average peak area for the sample by the response factor to give the amount of H2S present in ppm. For samples that were diluted, multiply the concentration by the correct dilution factor to give the amount of H2S in the undiluted sample (Figure 6).</li>
		</ol>
		</li>
	</ol>
	</li>
</ol>
<img alt="Figure 4" src="/files/ftp_upload/53416/53416fig4.jpg" /> 
Figure 4. Crude sample spiked with H 2 S. Two overlaid chromatograms illustrating the change expected when spiking a crude sample with H2S. <a href="https://www.jove.com/files/ftp_upload/53416/53416fig4large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 5" src="/files/ftp_upload/53416/53416fig5.jpg" /> 
Figure 5. Gas chromatogram data analysis. A screenshot of a data analysis program highlighting the location of an H2S peak in a sample and the peak area to be used to determine the concentration of H2S. <a href="https://www.jove.com/files/ftp_upload/53416/53416fig5large.jpg" target="_blank">Please click here to view a larger version of this figure.</a> <a href="https://www.jove.com/files/ftp_upload/53416/53416fig5large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 6" src="/files/ftp_upload/53416/53416fig6.jpg" /> 
Figure 6. Sample spreadsheet for data analysis. A screenshot of a spreadsheet program showing an example of how to calculate the concentration of H2S using the area of the calibration standard peak and the area of the sample peak. <a href="https://www.jove.com/files/ftp_upload/53416/53416fig6large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<ol start="2">
	<li>Gas
	<ol>
		<li>Identify the H2S peak in each chromatogram by matching the retention time of the H2S peak used to calibrate in Section 3.2.</li>
		<li>Use the data analysis software accompanying the gas chromatograph to integrate the peak area for each H2S peak in the collected data, and calculate the average peak area for each sample.</li>
		<li>Using the response factor determined in Section 3.2, divide the average peak area for the sample by the response factor to give the amount of H2S present in ppm. For samples that used a smaller syringe volume, multiply the concentration by the correct dilution factor to give the amount of H2S that would be present in a 250 &#181;l syringe (i.e., (250 &#181;l/25 &#181;l for a 25 &#181;l syringe).</li>
	</ol>
	</li>
</ol>

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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>

The authors have nothing to disclose.

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 ...

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19.0K Views.  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. 

Video: 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.