The SBO project &#8220;Bioleum&#8221; (IWT-SBO 130039) supported by the Institute for Promotion of Innovation through Science and Technology in Flanders (IWT) and the &#8216;Long Term Structural Methusalem Funding by the Flemish Government&#8217; are acknowledged.

Caution: Please consult relevant material safety data sheets (MSDS) of all compounds before use. Appropriate safety practices are recommended. Solutions and samples should be prepared in the fume hood, while using personal protective equipment. Best practice implies use of safety glasses, protection laboratory gloves, lab coat, full length pants, and closed-toe shoes. The reactor should be properly sealed as several reactants and reaction products can be acutely toxic and carcinogenic.
1. Offline GC &#215; GC&#8211;NCD Analysis
<ol>
	<li>Sample Preparation for offline GC &#215; GC analysis
	<ol>
		<li>Select 2-chloropyridine as an internal standard. Make sure that the concentration of the internal standard in the prepared sample is within the range of the concentrations of nitrogen containing compounds present in the analyzed mixture. The concentration of the internal standard must be at least ten times higher than the detection limit of the NCD. Furthermore the concentration of the internal standard should not be more than two times higher than the concentration of the nitrogen compound with the highest concentration in the sample.</li>
		<li>Prepare and weigh two glass vials using an analytical balance.</li>
		<li>Add 20.498 mg of 2-chloropyridine to the first vial using an analytical balance.</li>
		<li>Tare the balance with the first vial and add 1024.287 mg of a shale oil sample. Gently mix the vial content.</li>
		<li>Transfer 23.369 mg of the prepared mixture into a second vial and add 435.195 mg of the original shale oil sample. The obtained concentration of the internal standard in the sample is approximately 1,000 ppmw.</li>
	</ol>
	</li>
	<li>GC &#215; GC&#8211;NCD analysis and operating conditions 
	<ol>
		<li>Perform the analysis using a GC &#215; GC equipped with a dual-stage cryogenic liquid CO2 modulator45.
		<ol>
			<li>Connect the first dimension non-polar column (PONA, 50 m L &#215; 0.25 mm I.D. &#215; 0.5 &#181;m df) directly to the second dimension mid-polar column (BPX-50, 2 m L &#215; 0.25 mm I.D. &#215; 0.25 &#181;m df). Apply the GC &#215; GC operating conditions optimized for detection of nitrogen containing compounds in shale oil, with the parameters presented in Table 1.</li>
			<li>Inject the sample using the auto sampler, with the settings stated in the Supplementary Table.</li>
		</ol>
		</li>
		<li>For the NCD, set the flow rates at 5 and 11 ml min-1 for the H2 and O2 respectively, while keeping the burner temperature at 1,198 K. Use a data acquisition rate of 100 Hz. The detector settings are presented in Table 1.</li>
	</ol>
	</li>
	<li>Reprocessing of results
	<ol>
		<li>Perform data acquisition using the data system for the NCD. Export the raw data to a .cdf file and import into an analytical software (e.g., GCImage).</li>
		<li>Use the analytical software to construct the contour plot, to determine the retention times, and to perform peak fitting and blob integration according to the software protocols. Identify each blob as a compound of a specific nitrogen group with a specific carbon number. 
		Note: Response signal of NCD is equimolar6,46,47,48, hence the procedure for quantification of nitrogen containing compounds in the sample is straightforward.</li>
		<li>Calculate the concentration of detected compounds using the following equation: 
		<img alt="Equation 1" src="/files/ftp_upload/54236/54236eq1.jpg" /> 
		where Vi and Vst are the peak volumes of the nitrogen containing compound i and the internal standard respectively. Wst is the concentration of the internal standard compound, Ni is the number of nitrogen atoms in compound i, Mi and Mst are the molar masses of the nitrogen containing compounds and of the nitrogen internal standard respectively6.</li>
	</ol>
	</li>
</ol>
2. On-line Analysis
<ol>
	<li>Pilot plant steam cracking unit 
	Note: The pilot plant steam cracker consists of three sections: the feed section, the furnace/reactor section and the analysis section. The unit is explained in detail elsewhere18,49,50,51. A schematic description of the setup can be found in the Supplementary Information.
	<ol>
		<li>During the experiments, as heptane is fed using a computer controlled rotary pump by setting the flowrate using the Programmable Logical Controller (PLC), introduce pyridine to the reactor convection section by manually setting the speed of the piston pump. The diluent used depends on the purpose of the test and can be varied. Depending on the requirements of the experiment, use the gas controllers for helium and nitrogen dilution, and regulate the water feeding pump frequency for steam dilution.</li>
		<li>Prior to the reaction section of the furnace, evaporate and mix the feedstock in two separately heated zones kept at a temperature of 773 K.</li>
		<li>Impose a temperature profile to the Incoloy 800HT 12.4 m long and 9 mm internal diameter reactor by setting the temperatures in the five heated zones using the PLC. Different experiments with varying process conditions can be performed. Use the process conditions applied to perform method testing as outlined in Table 2.</li>
	</ol>
	</li>
	<li>Analysis methodology
	<ol>
		<li>Use the refinery gas analyzer (RGA) equipped with three detectors working on parallel channels in order to detect as many compounds as possible. Two TCD&#39;s and a FID allow detection of CO, CO2, H2, and hydrocarbons up to four carbon atoms, using three different columns for separating the reaction products. The RGA setting are presented in Table 3.</li>
		<li>For the GC &#215; GC set-ups, use a non-polar PONA (50 m L &#215; 0.25 mm I.D. &#215; 0.5 &#181;m df) column in the first dimension and a mid-polar BPX-50 (2 m L &#215; 0.15 mm I.D. &#215; 0.15 &#181;m df) column in the second dimension. Ensure that the temperature in the oven can be lowered to 233 K by addition of liquid nitrogen inside the GC oven. Use the GC &#215; GC settings given in Table 4 for the on-line analyses.</li>
		<li>Ensure that TOF-MS electron impact ionization is 70 eV, and detector voltage 1,700 V by setting these values in the software. Additionally set the acquisition frequency to 30 spectra/sec in a mass range of 15-400 amu in the same software.</li>
		<li>For the NCD, manually set flow rates at 5 and 11 ml min-1 for the H2 and O2 respectively, while keeping the burner temperature at 1,198 K. The data acquisition rate needs to be 100 Hz.</li>
		<li>For FID H2, air and N2 (make-up gas) flow rates are respectively 35, 350 and 35 ml min-1. Ensure that the FID temperature is set at 573 K with a data acquisition rate of 100 Hz.</li>
		<li>Sample the pilot plant effluent on-line, i.e., during pilot plant operation, and at high temperature (673 - 773 K). Use a valve-based sampling system, positioned in the sampling oven kept at 573 K, see Figure 1.
		<ol>
			<li>Turn the pneumatic 6-port 2-way valve to the position shown in Figure 1a using the PLC, flush the sample loop for at least 2 min.</li>
			<li>Turn the pneumatic 6-port 2-way valve to the position shown in Figure 1b using the PLC, a gaseous sample from the sample loop is carried with helium and injected onto selected GC &#215; GC. Keep the valve in the injection position for 20 sec. Turn the pneumatic 6-port 2-way valve back in the position shown in Figure 1a.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Internal standard addition
	<ol>
		<li>Use 2-chloropyridine as an internal standard for the NCD analyses. The introduced amount of this compound depends on the purpose of the experiment (values illustrated in Table 2). To add 2-chloropyridine precisely and uniformly, dissolve the compound in n-hexane (values illustrated in Table 2) and gentle stir the mixture after preparation.</li>
		<li>Add the internal standard 2-chloropyridine continuously by pumping the prepared mixture through a capillary transfer line, which is centrally positioned in the product stream before the sampling system. For this purpose use a peristaltic pump and keep the flow rate stable (values indicated in Table 2).</li>
	</ol>
	</li>
	<li>Data acquisition and quantification 
	<ol>
		<li>Acquire the data obtained with TOF-MS, and use the results for product identification and establishing the retention times of the reaction products. Acquisition and reprocessing of data obtained from FID is similar to the procedure applied to reprocessing of results gathered using the NCD, as explained in section 1.3.2.</li>
		<li>Recalculate the product yields using an internal standard18. Introduce a fixed amount of nitrogen (N2) continuously to the product stream and use it as a reference compound as shown in Figure 2.</li>
		<li>Combine the data obtained on the different instruments. Apply the calibration factors for each compound depending on the detector.
		<ol>
			<li>Set the methane calibration factor to 1.</li>
			<li>Obtain response factors relative to methane for permanent gases detectable on RGA by calibration. Ensure that for all major compounds detected on the GC &#215; GC the relative response factors are determined by calibration. For minor products use the FID calibration factors reported by Dietz52. If the response factors for a compound are not available, calculate values using the group contribution method developed by Dierickx et al.53.</li>
			<li>Methane functions as a secondary internal standard, and its concentration is needed to determine the concentrations based on the peaks of the GC &#215; GC&#8211;FID chromatogram. Therefore determine the methane mass flow rate using equation 2: 
			<img alt="Equation 2" src="/files/ftp_upload/54236/54236eq2.jpg" /> 
			Where, fCH4 and fN2 are the calibration factors of methane and nitrogen on TCD respectively. ACH4 and AN2 are peak areas obtained during analysis, while <img alt="Equation 3" src="/files/ftp_upload/54236/54236eq3.jpg" /> is the nitrogen mass flow rate added to the effluent stream.</li>
		</ol>
		</li>
		<li>Carry out quantification of the nitrogen containing products by applying the procedure explained in section 1.3.3.</li>
	</ol>
	</li>
</ol>

The authors have nothing to disclose.

The described experimental procedures enabled a successful comprehensive off-line and on-line identification and quantification of nitrogen containing compounds in the studied samples.
The separation of nitrogen containing compounds in shale oil was accomplished using GC &#215; GC&#8211;NCD, as shown in Figure 3. Since the NCD cannot be used for identification, the retention times of the observed species need to be established in advance by carrying out analyses on the GC &#21...

The reserves of light sweet crude oils are gradually diminishing, and hence, alternative fossil resources are being considered to be used in the energy and petrochemical industry. In addition, renewables such as bio-oils produced by fast pyrolysis of biomass are becoming a more attractive resources of bio-based fuels and chemicals. Nevertheless, heavy crude oil is a logical first choice because of the large proven reserves in Canada and Venezuela1-3. The latter are being recognized as the largest crude oil reserves in the world and their composition is similar to the composition of natural bitumen. Similar to bio-oils, heavy crude oils differ from light crude oils by their high viscosity at reservoir temperatures, high density (low API gravity), and significant contents of nitrogen, oxygen, and sulfur containing compounds4,5. Another promising alternative is shale oil, derived from oil shale. Oil shale is a fine-grained sedimentary rock containing kerogen, a mixture of organic chemical compounds with a molar mass as high as 1,000 Da6. Kerogen can contain organic oxygen, nitrogen, and sulfur in the hydrocarbon matrix; depending on the origin, age, and the extraction conditions. Global characterization methods have shown that the concentration of heteroatoms (S, O and N) in shale oil and heavy crude oils is typically substantially higher than the specifications set for the products used in for example the petrochemical industry6. It is well documented that nitrogen containing compounds present in heavy conventional crude oil and shale oil have a negative effect on the catalyst activity in hydrocracking, catalytic cracking and reforming processes7. Similarly, it has been reported that the presence of nitrogen containing compounds are a safety concern because they promote gum formation in the cold-box of a steam cracker8.
These processing and safety challenges are a strong driver to improve the current methods for off-line and on-line characterization of nitrogen containing compounds in complex hydrocarbon matrices. Two-dimensional gas chromatography (GC &#215; GC) coupled with a nitrogen chemiluminescence detector (NCD) is a superior characterization technique compared to one-dimensional gas chromatography (GC) for analyzing conventional diesels or liquefied coal samples7. Recently a method has been developed and applied to the offline characterization of nitrogen content in shale oil6, the identification of extracted nitrogen compounds present in middle distillates9, and the determination of the detailed composition of plastic waste pyrolysis oil10.
It is thus clear that GC &#215; GC analysis is a powerful offline processing technique for analyzing complex mixtures11-17. However, on-line application is more challenging due to the need for a reliable and non-discriminating sampling methodology. One of the first developed methodologies for comprehensive on-line characterization was demonstrated by analyzing steam cracking reactor effluents using a TOF-MS and a FID18. The optimization of the GC settings and an appropriate column combination enabled analysis of samples consisting of hydrocarbons ranging from methane up to polyaromatic hydrocarbons (PAHs)18. The present work takes this method to a new level by extending it to the identification and quantification of nitrogen compounds present in the complex hydrocarbon mixtures. Such a method is among others needed to improve fundamental understanding of the role these compounds play in several processes and applications. To the authors&#39; best knowledge, information concerning kinetics of conversion processes of nitrogen containing compounds is scarce19, partly due to the lack of an adequate method to identify and quantify nitrogen containing compounds in the reactor effluent. Establishing the methodology for offline and on-line analyses is thus a prerequisite before one can even attempt feedstock reconstruction20-27 and kinetic modeling. One of the fields which would benefit from the accurate identification and quantification of nitrogen containing compounds is steam cracking or pyrolysis. Bio and heavy fossil feeds for steam cracking or pyrolysis reactors contain thousands of hydrocarbons and compounds that contain heteroatoms. Moreover, because of the complexity of the feed and the radical nature of the occurring chemistry, ten thousands of reactions can occur among the thousands free radical species28, which makes the reactor effluent even more complex than the starting material.
In hydrocarbon mixtures nitrogen is mainly present in aromatic structures, e.g., as pyridine or pyrrole; hence most experimental efforts have been dedicated to the decomposition of these structures. Hydrogen cyanide and ethyne were reported as major products for the thermal decomposition of pyridine studied in a temperature range of 1,148-1,323 K. Other products such as aromatics and nonvolatile tars were also detected in minor quantities29. The thermal decomposition of pyrrole was investigated in a broader temperature range of 1,050-1,450 K using shock wave experiments. The main products were 3-butenenitrile, cis and trans 2-butenenitrile, hydrogen cyanide, acetonitrile, 2-propenenitrile, propanenitrile, and propiolonitrile30. Additionally thermal decomposition shock tube experiments were performed for pyridine at elevated temperatures resulting in comparable product spectra31,32. Product yields in these studies have been determined by applying GC&#39;s equipped with a FID, a nitrogen-phosphorus detector (NPD)31, a mass spectrometer (MS)32 and a Fourier transform infrared (FTIR) spectrometer32. A similar methodology implementing the FID and the NPD was applied to analyze the shale oil pyrolysis products in a continuous flow reactor8. Using a cold trap at 273.15 K and GC-MS, Winkler et al. 33 showed that during pyridine pyrolysis heteroatom-containing aromatic compounds are formed. Zhang et al.34 and Debono et al.35 applied the method of Winkler et al. for studying the pyrolysis of organic waste. The nitrogen rich reaction products were analyzed on-line, using a GC coupled to a thermal conductivity detector (TCD)34. The collected tars were analyzed offline using GC-MS34,35. Simultaneous pyrolysis of toluene and pyridine showed a difference in soot formation tendency compared to pyridine pyrolysis, indicating the complex nature of the free-radical reactions31,36.
One of the most comprehensive analytical methodologies was developed by Nathan and co-workers37. They used FTIR, nuclear magnetic resonance (NMR) and GC-MS for analyzing decomposition products of pyridine and diazine and electron paramagnetic resonance (EPR) spectroscopy for tracing free radical species. FTIR analysis can be a very effective approach for the identification of a large range of products, even PAHs38-40, nevertheless quantification is extremely challenging. Calibration requires a full set of infrared spectra at different concentrations for each target species at a specific temperature and pressure41. Recent work of Hong et al. demonstrated the possibilities of using molecular-beam mass spectrometry (MBMS) and tunable synchrotron vacuum ultraviolet photoionization for determination of products and intermediates during pyrrole and pyridine decomposition42,43. This experimental method enables selective identification of isomeric intermediates and near-threshold detection of radicals without inflicting fragmentation of the analyzed species44. However, the uncertainty on the measured concentrations using MBMS analysis is also substantial.
In this work, first the offline comprehensive characterization results of the complex shale oil are reported. Next, the limitations of using an on-line GC &#215; GC-TOF-MS/FID for the analysis of nitrogen compounds in a complex hydrocarbon matrix are discussed. Finally, the newly developed methodology for the on-line quantification of nitrogen containing compounds by GC &#215; GC&#8211;NCD is demonstrated. The qualitative analysis of products was carried out using TOF-MS, while FID and NCD were used for quantification. The application of the NCD is a substantial improvement compared to using the FID because of its higher selectivity, lower detection limit and equimolar response.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>2-Chloropyridine, 99%</td>
			<td>Sigma Aldrich</td>
			<td>C69802</td>
			<td>Highly toxic</td>
		</tr>
		<tr>
			<td>Shale oil</td>
			<td>Origin Colorado, US</td>
			<td>Piceance Basin in 
			Colorado, USA</td>
			<td>Toxic</td>
		</tr>
		<tr>
			<td>Pyridine, 99.8%</td>
			<td>Sigma Aldrich</td>
			<td>270970</td>
			<td>Highly toxic</td>
		</tr>
		<tr>
			<td>Carbon Dioxide, industrial grade refrigerated liquid</td>
			<td>PRAXAIR</td>
			<td>CDINDLB0D</td>
			<td>Wear safety gloves and glasses</td>
		</tr>
		<tr>
			<td>Helium, 99.99%</td>
			<td>PRAXAIR</td>
			<td>6.0</td>
			<td></td>
		</tr>
		<tr>
			<td>Hydrogen, 99.95%</td>
			<td>Air Liquide</td>
			<td>695A-49</td>
			<td>Flammable</td>
		</tr>
		<tr>
			<td>Oxygen</td>
			<td>Air Liquide</td>
			<td>905A-49+</td>
			<td>Flammable</td>
		</tr>
		<tr>
			<td>Air</td>
			<td>Air Liquide</td>
			<td>365A-49X</td>
			<td></td>
		</tr>
		<tr>
			<td>Nitrogen</td>
			<td>Air Liquide</td>
			<td>765A-49</td>
			<td></td>
		</tr>
		<tr>
			<td>Hexane, 95+%</td>
			<td>Chemlab</td>
			<td>CL00.0803.9025</td>
			<td>Toxic</td>
		</tr>
		<tr>
			<td>Heptane, 99+%</td>
			<td>Chemlab</td>
			<td>CL00.0805.9025</td>
			<td>Toxic</td>
		</tr>
		<tr>
			<td>Nitrogen, industrial grade refrigerated liquid</td>
			<td>PRAXAIR</td>
			<td>P0271L50S2A001</td>
			<td>Wear safety gloves and glasses</td>
		</tr>
		<tr>
			<td>Autosampler</td>
			<td>Thermo Scientific, Interscience</td>
			<td>AI/AS 3000</td>
			<td></td>
		</tr>
		<tr>
			<td>High temperature 6 port/2 position valve</td>
			<td>Valco Instruments Company Incorporated</td>
			<td>SSACGUWT</td>
			<td></td>
		</tr>
		<tr>
			<td>Gas chromatograph</td>
			<td>Thermo Scientific, Interscience</td>
			<td>Trace GC ultra</td>
			<td></td>
		</tr>
		<tr>
			<td>Rafinery Gas Analyzer</td>
			<td>Thermo Scientific, Interscience</td>
			<td>KAV00309</td>
			<td></td>
		</tr>
		<tr>
			<td>rtx-1-PONA column</td>
			<td>Restek Pure Chromatography</td>
			<td>10195-146</td>
			<td></td>
		</tr>
		<tr>
			<td>BPX-50 column</td>
			<td>SGE Analytical science</td>
			<td>54741</td>
			<td></td>
		</tr>
		<tr>
			<td>TOF-MS</td>
			<td>Thermo Scientific, Interscience</td>
			<td>Tempus Plus 1.4 SR1 Finnigan</td>
			<td></td>
		</tr>
		<tr>
			<td>NCD</td>
			<td>Agilent Technologgies</td>
			<td>NCD 255</td>
			<td></td>
		</tr>
		<tr>
			<td>Chrom-card</td>
			<td>Thermo Scientific, Interscience</td>
			<td>HyperChrom 2.4.1</td>
			<td></td>
		</tr>
		<tr>
			<td>Xcalibur software</td>
			<td>Thermo Scientific, Interscience</td>
			<td>1.4 SR1</td>
			<td></td>
		</tr>
		<tr>
			<td>Chrom-card software</td>
			<td>Thermo Scientific, Interscience</td>
			<td>HyperChrom 2.7</td>
			<td></td>
		</tr>
		<tr>
			<td>GC image software</td>
			<td>Zoex Corporation</td>
			<td>GC image 2.3</td>
			<td></td>
		</tr>
	</tbody>
</table>

on-line analysis of nitrogen containing compounds in complex hydrocarbon matrixes

The shift to heavy crude oils and the use of alternative fossil resources such as shale oil are a challenge for the petrochemical industry. The composition of heavy crude oils and shale oils varies substantially depending on the origin of the mixture. In particular they contain an increased amount of nitrogen containing compounds compared to the conventionally used sweet crude oils. As nitrogen compounds have an influence on the operation of thermal processes occurring in coker units and steam crackers, and as some species are considered as environmentally hazardous, a detailed analysis of the reactions involving nitrogen containing compounds under pyrolysis conditions provides valuable information. Therefore a novel method has been developed and validated with a feedstock containing a high nitrogen content, i.e., a shale oil. First, the feed was characterized offline by comprehensive two-dimensional gas chromatography (GC &#215; GC) coupled with a nitrogen chemiluminescence detector (NCD). In a second step the on-line analysis method was developed and tested on a steam cracking pilot plant by feeding pyridine dissolved in heptane. The former being a representative compound for one of the most abundant classes of compounds present in shale oil. The composition of the reactor effluent was determined via an in-house developed automated sampling system followed by immediate injection of the sample on a GC &#215; GC coupled with a time-of-flight mass spectrometer (TOF-MS), flame ionization detector (FID) and NCD. A novel method for quantitative analysis of nitrogen containing compounds using NCD and 2-chloropyridine as an internal standard has been developed and demonstrated.

The chromatogram obtained using the offline GC &#215; GC&#8211;NCD for characterization of nitrogen containing compounds in a shale oil sample is given in Figure 3. The following classes were identified: pyridines, anilines, quinolines, indoles, acridines, and carbazoles. Moreover, detailed quantification of the individual compounds was possible. The gathered data was used to determine the individual compound concentrations, and the obtained values are presented in <stron...

Watch this Scientific Journal Video about On-line Analysis of Nitrogen Containing Compounds in Complex Hydrocarbon Matrixes at JoVE.com

On-line Analysis of Nitrogen Containing Compounds in Complex Hydrocarbon Matrixes

A method combining comprehensive two-dimensional gas chromatography with nitrogen chemiluminescence detection has been developed and applied to on-line analysis of nitrogen containing compounds in a complex hydrocarbon matrix.

The shift to heavy crude oils and the use of alternative fossil resources such as shale oil are a challenge for the petrochemical industry. The ...

on-line-analysis-nitrogen-containing-compounds-complex-hydrocarbon

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Chemistry

10.6K Views.  Ghent University. A method combining comprehensive two-dimensional gas chromatography with nitrogen chemiluminescence detection has been developed and applied to on-line analysis of nitrogen containing compounds in a complex hydrocarbon matrix.

Video: On-line Analysis of Nitrogen Containing Compounds in Complex Hydrocarbon Matrixes

Improved In-gel Reductive &#946;-Elimination for Comprehensive O-linked and Sulfo-glycomics by Mass Spectrometry

Separation of proteins by SDS-PAGE followed by in-gel proteolytic digestion of resolved protein bands has produced high-resolution proteomic analysis of biological samples. Similar approaches, that would allow in-depth analysis of the glycans carried by glycoproteins resolved by SDS-PAGE, require special considerations in order to maximize recovery and sensitivity when using mass spectrometry (MS) as the detection method. A major hurdle to be overcome in achieving high-quality data is the removal of gel-derived contaminants that interfere with MS analysis. The sample workflow presented here is robust, efficient, and eliminates the need for in-line HPLC clean-up prior to MS. Gel pieces containing target proteins are washed in acetonitrile, water, and ethyl acetate to remove contaminants, including polymeric acrylamide fragments. O-linked glycans are released from target proteins by in-gel reductive &#946;-elimination and recovered through robust, simple clean-up procedures. An advantage of this workflow is that it improves sensitivity for detecting and characterizing sulfated glycans. These procedures produce an efficient separation of sulfated permethylated glycans from non-sulfated (sialylated and neutral) permethylated glycans by a rapid phase-partition prior to MS analysis, and thereby enhance glycomic and sulfoglycomic analyses of glycoproteins resolved by SDS-PAGE.

In order to comprehensively explore the diversity of O-linked glycans, a new procedure for in-gel reductive &#946;-elimination, combined with permethylation and a rapid phase-partition method, is applied to the analysis of O-linked glycans directly released from glycoproteins resolved by SDS-PAGE and amenable to subsequent glycomic analysis by mass spectrometry.

Separation of proteins by SDS-PAGE followed by in-gel proteolytic digestion of resolved protein bands has produced high-resolution proteomic analysis of ...

Analysis of Volatile and Oxidation Sensitive Compounds Using a Cold Inlet System and Electron Impact Mass Spectrometry

This video presents a protocol for the mass spectrometrical analysis of volatile and oxidation sensitive compounds using electron impact ionization. The analysis of volatile and oxidation sensitive compounds by mass spectrometry is not easily achieved, as all state-of-the-art mass spectrometric methods require at least one sample preparation step, e.g., dissolution and dilution of the analyte (electrospray ionization), co-crystallization of the analyte with a matrix compound (matrix-assisted laser desorption/ionization), or transfer of the prepared samples into the ionization source of the mass spectrometer, to be conducted under atmospheric conditions. Here, the use of a sample inlet system is described which enables the analysis of volatile metal organyls, silanes, and phosphanes using a sector field mass spectrometer equipped with an electron impact ionization source. All sample preparation steps and the sample introduction into the ion source of the mass spectrometer take place either under air-free conditions or under vacuum, enabling the analysis of compounds highly susceptible to oxidation. The presented technique is especially of interest for inorganic chemists, working with metal organyls, silanes, or phosphanes, which have to be handled using inert conditions, such as the Schlenk technique. The principle of operation is presented in this video.

This video presents a protocol for the mass spectrometrical analysis of volatile and oxidation sensitive compounds using electron impact ionization. The presented technique is especially of interest for inorganic chemists, working with metal organyls, silanes, or phosphanes which have to be handled using inert conditions, such as the Schlenk technique.

This video presents a protocol for the mass spectrometrical analysis of volatile and oxidation sensitive compounds using electron impact ionization. The ...

Reductive Electropolymerization of a Vinyl-containing Poly-pyridyl Complex on Glassy Carbon and Fluorine-doped Tin Oxide Electrodes

Controllable electrode surface modification is important in a number of fields, especially those with solar fuels applications. Electropolymerization is one surface modification technique that electrodeposits a polymeric film at the surface of an electrode by utilizing an applied potential to initiate the polymerization of substrates in the Helmholtz layer. This useful technique was first established by a Murray-Meyer collaboration at the University of North Carolina at Chapel Hill in the early 1980s and utilized to study numerous physical phenomena of films containing inorganic complexes as the monomeric substrate. Here, we highlight a procedure for coating electrodes with an inorganic complex by performing reductive electropolymerization of the vinyl-containing poly-pyridyl complex onto glassy carbon and fluorine doped tin oxide coated electrodes. Recommendations on electrochemical cell configurations and troubleshooting procedures are included. Although not explicitly described here, oxidative electropolymerization of pyrrole-containing compounds follows similar procedures to vinyl-based reductive electropolymerization but are far less sensitive to oxygen and water.

A procedure for performing reductive electropolymerization of vinyl-containing compounds onto glassy carbon and fluorine doped tin-oxide coated electrodes is presented. Recommendations on electrochemical cell configurations and troubleshooting procedures are included. Although not explicitly described here, oxidative electropolymerization of pyrrole-containing compounds follows similar procedures to vinyl-based reductive electropolymerization.

Controllable electrode surface modification is important in a number of fields, especially those with solar fuels applications. Electropolymerization is ...

Supercritical Nitrogen Processing for the Purification of Reactive Porous Materials

Supercritical fluid extraction and drying methods are well established in numerous applications for the synthesis and processing of porous materials. Herein, nitrogen is presented as a novel supercritical drying fluid for specialized applications such as in the processing of reactive porous materials, where carbon dioxide and other fluids are not appropriate due to their higher chemical reactivity. Nitrogen exhibits similar physical properties in the near-critical region of its phase diagram as compared to carbon dioxide: a widely tunable density up to ~1 g ml-1, modest critical pressure (3.4 MPa), and small molecular diameter of ~3.6 &#197;. The key to achieving a high solvation power of nitrogen is to apply a processing temperature in the range of 80-150 K, where the density of nitrogen is an order of magnitude higher than at similar pressures near ambient temperature. The detailed solvation properties of nitrogen, and especially its selectivity, across a wide range of common target species of extraction still require further investigation. Herein we describe a protocol for the supercritical nitrogen processing of porous magnesium borohydride.

Nitrogen is an effective supercritical fluid for extraction or drying processes due to its small molecular size, high density in the near-liquid supercritical regime, and chemical inertness. We present a supercritical nitrogen drying protocol for the purification treatment of reactive, porous materials.

Supercritical fluid extraction and drying methods are well established in numerous applications for the synthesis and processing of porous materials. ...

A Direct, Early Stage Guanidinylation Protocol for the Synthesis of Complex Aminoguanidine-containing Natural Products

The guanidine functional group, displayed most prominently in the amino acid arginine, one of the fundamental building blocks of life, is an important structural element found in many complex natural products and pharmaceuticals. Owing to the continual discovery of new guanidine-containing natural products and designed small molecules, rapid and efficient guanidinylation methods are of keen interest to synthetic and medicinal organic chemists. Because the nucleophilicity and basicity of guanidines can affect subsequent chemical transformations, traditional, indirect guanidinylation is typically pursued. Indirect methods commonly employ multiple protection steps involving a latent amine precursor, such as an azide, phthalimide, or carbamate. By circumventing these circuitous methods and employing a direct guanidinylation reaction early in the synthetic sequence, it was possible to forge the linear terminal guanidine containing backbone of clavatadine A to realize a short and streamlined synthesis of this potent factor XIa inhibitor. In practice, guanidine hydrochloride is elaborated with a carefully constructed protecting array that is optimized to survive the synthetic steps to come. In the preparation of clavatadine A, direct guanidinylation of a commercially available diamine eliminated two unnecessary steps from its synthesis. Coupled with the wide variety of known guanidine protecting groups, direct guanidinylation evinces a succinct and efficient practicality inherent to methods that find a home in a synthetic chemist&#39;s toolbox.

Here, we present a protocol for direct, early stage guanidinylation that enables rapid total synthesis of aminoguanidine-containing small organic molecules. An advanced synthetic intermediate used in the synthesis of a blood coagulation factor XIa inhibitor was prepared using this protocol.

The guanidine functional group, displayed most prominently in the amino acid arginine, one of the fundamental building blocks of life, is an important ...

Synthesis of a Water-soluble Metal&#8211;Organic Complex Array

We demonstrate a method for the synthesis of a water-soluble multimetallic peptidic array containing a predetermined sequence of metal centers such as Ru(II), Pt(II), and Rh(III). The compound, named as a water-soluble metal-organic complex array (WSMOCA), is obtained through 1) the conventional solution-chemistry-based preparation of the corresponding metal complex monomers having a 9-fluorenylmethyloxycarbonyl (Fmoc)-protected amino acid moiety and 2) their sequential coupling together with other water-soluble organic building units on the surface-functionalized polymeric resin by following the procedures originally developed for the solid-phase synthesis of polypeptides, with proper modifications. Traces of reactions determined by mass spectrometric analysis at the representative coupling steps in stage 2 confirm the selective construction of a predetermined sequence of metal centers along with the peptide backbone. The WSMOCA cleaved from the resin at the end of stage 2 has a certain level of solubility in aqueous media dependent on the pH value and/or salt content, which is useful for the purification of the compound.

A potential general method for the synthesis of water-soluble multimetallic peptidic arrays containing a predetermined sequence of metal centers is presented.

We demonstrate a method for the synthesis of a water-soluble multimetallic peptidic array containing a predetermined sequence of metal centers such as ...

Real-time Breath Analysis by Using Secondary Nanoelectrospray Ionization Coupled to High Resolution Mass Spectrometry

Exhaled volatile organic compounds (VOCs) have aroused considerable interest, since they can serve as biomarkers for disease diagnosis and environmental exposure in a non-invasive manner. In this work, we present a protocol to characterize the exhaled VOCs in real time by using secondary nanoelectrospray ionization coupled to high resolution mass spectrometry (Sec-nanoESI-HRMS). The homemade Sec-nanoESI source was readily set up based on a commercial nanoESI source. Hundreds of peaks were observed in the background-subtracted mass spectra of exhaled breath, and the mass accuracy values are -4.0-13.5 ppm and -20.3-1.3 ppm in the positive and negative ion detection modes, respectively. The peaks were assigned with accurate elemental composition according to the accurate mass and isotopic pattern. Less than 30 s is used for one exhalation measurement, and it takes approximately 7 min for six replicated measurements.

A protocol for characterizing chemical composition of exhaled breath in real time by using secondary nanoelectrospray ionization coupled to high resolution mass spectrometry is demonstrated.

Exhaled volatile organic compounds (VOCs) have aroused considerable interest, since they can serve as biomarkers for disease diagnosis and environmental ...

Preparation of Hollow Polystyrene Particles and Microcapsules by Radical Polymerization of Janus Droplets Consisting of Hydrocarbon and Fluorocarbon Oils

In this article, we have demonstrated a method for producing hollow particles and microcapsules using oil droplets consisting of hydrocarbon oil (styrene) and fluorocarbon oil (perfluoro-n-octane, PFO) in aqueous surfactant (sodium dodecylsulfate, SDS) solutions. Since fluorocarbon oils are immiscible with hydrocarbon oils, the two oils are separated. Emulsions are prepared by stirring styrene/PFO/aqueous SDS solution mixtures at 80 &#176;C. The type of emulsions and the morphology of droplets in the emulsions are observed by light microscope and scanning confocal fluorescence microscope. It is found that oil droplets with Janus-type morphologies consisting of mutually immiscible styrene and PFO are formed in aqueous SDS solutions. Polystyrene particles are fabricated by radical polymerization of the ternary mixtures of styrene/PFO/aqueous SDS solution at 80 &#176;C. The morphologies of the polystyrene are confirmed by scanning electron microscopy and scanning transmission electron microscopy observations. These observations show the preparation of hollow polystyrene particles with a single hole on the surface. To our knowledge, this method is a novel strategy using the immiscibility of hydrocarbon and fluorocarbon oils. The hollow particles can also be applied to the preparation of microcapsules.

A protocol for the fabrication of hollow polymer particles and microcapsules by radical polymerization using emulsions consisting of styrene, perfluoro-n-octane, and aqueous SDS (sodium dodecylsulfate) solution is presented.

In this article, we have demonstrated a method for producing hollow particles and microcapsules using oil droplets consisting of hydrocarbon oil (styrene) ...

Negative Additive Manufacturing of Complex Shaped Boron Carbides

Boron carbide (B4C) is one of the hardest materials in existence. However, this attractive property also limits its machineability into complex shapes for high wear, high hardness, and lightweight material applications such as armors. To overcome this challenge, negative additive manufacturing (AM) is employed to produce complex geometries of boron carbides at various length scales. Negative AM first involves gelcasting a suspension into a 3D-printed plastic mold. The mold is then dissolved away, leaving behind a green body as a negative copy. Resorcinol-formaldehyde (RF) is used as a novel gelling agent because unlike traditional hydrogels, there is little to no shrinkage, which allows for extremely complex molds to be used. Furthermore, this gelling agent can be pyrolyzed to leave behind ~50 wt% carbon, which is a highly effective sintering aid for B4C. Due to this highly homogenous distribution of in situ carbon within the B4C matrix, less than 2% porosity can be achieved after sintering. This protocol highlights in detail the methodology for creating near fully dense boron carbide parts with highly complex geometries.

A method called negative additive manufacturing is used to produce near fully dense complex shaped boron carbide parts of various length scales. This technique is possible via the formulation of a novel suspension involving resorcinol-formaldehyde as a unique gelling agent that leaves behind a homogenous carbon sintering aid after pyrolysis.

Boron carbide (B4C) is one of the hardest materials in existence. However, this attractive property also limits its machineability into complex shapes for ...

Molten-Salt Synthesis of Complex Metal Oxide Nanoparticles

The development of feasible synthesis methods is critical for the successful exploration of novel properties and potential applications of nanomaterials. Here, we introduce the molten-salt synthesis (MSS) method for making metal oxide nanomaterials. Advantages over other methods include its simplicity, greenness, reliability, scalability, and generalizability. Using pyrochlore lanthanum hafnium oxide (La2Hf2O7) as a representative, we describe the MSS protocol for the successful synthesis of complex metal oxide nanoparticles (NPs). Furthermore, this method has the unique ability to produce NPs with different material features by changing various synthesis parameters such as pH, temperature, duration, and post-annealing. By fine-tuning these parameters, we are able to synthesize highly uniform, non-agglomerated, and highly crystalline NPs. As a specific example, we vary the particle size of the La2Hf2O7&#160;NPs by changing the concentration of the ammonium hydroxide solution used in the MSS process, which allows us to further explore the effect of particle size on various properties. It is expected that the MSS method will become a more popular synthesis method for nanomaterials and more widely employed in the nanoscience and nanotechnology community in the upcoming years.

Here, we demonstrate a unique, relatively low-temperature, molten-salt synthesis method for preparing uniform complex metal oxide lanthanum hafnate nanoparticles.

The development of feasible synthesis methods is critical for the successful exploration of novel properties and potential applications of nanomaterials. ...