Name: analysis of volatile and oxidation sensitive compounds using a cold inlet system and electron impact mass spectrometry
Uploaded: 2014-09-05T15:00:00
Description: Watch this Scientific Journal Video about Analysis of Volatile and Oxidation Sensitive Compounds Using a Cold Inlet System and Electron Impact Mass Spectrometry at JoVE.com

JS is indebted to Prof. B. Hoge of the Inorganic Chemistry department, Bielefeld University, for the idea of establishing the presented inlet system. The analyzed phosphane was a generous gift from Prof. B. Hoge. Sample preparation of the analyzed compound was performed by M. Wiesemann. Photographs of the phospane were taken by Dr. J. Bader. The mechanical workshop of the faculty of chemistry is acknowledged for the manufacturing of the interface and the glass workshop of the faculty of chemistry for the manufacturing of the lockable test tubes with flanges. Prof. B. Hoge and Prof. H. Gr&#246;ger are acknowledged for funding of this publication.

1. Sample Preparation
<ol>
	<li>Use custom-made lockable test tubes with a flange (Figure 1) for transportation and transfer of the samples into the mass spectrometer. Prior to filling with sample, evacuate the lockable test tubes attached to a multiple manifold Schlenk line and remove residual water by heating with a heat gun. Vent the test tube with dry Argon and evacuate again, while heating.</li>
	<li>Immerse the lockable test tube into a cold trap filled with liquid nitrogen (CAUTION: Be careful w...

<ol>
	<li>Field, F. H., Franklin, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Electron Impact phenomena and the Properties of Gaseous Ions Revised Edition. , (1957).</li><li>Schaeffer, O. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+Improved+Mass+Spectrometer+Ion+Source.">An Improved Mass Spectrometer Ion Source.</a> Rev. Sci. Instrum. 25, 660-662 (1954).</li><li>Yamashita, M., Fenn, J. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrospray+Ion+Source+-+Another+Variation+of+the+Free-Jet+Theme.">Electrospray Ion Source - Another Variation of the Free-Jet Theme.</a> J. Phys. Chem. 88, 4451-4459 (1984).</li><li>Lubben, A. T., McIndoe, J. S., Weller, A. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Coupling+an+electrospray+ionization+mass+spectrometer+with+a+glovebox:+A+straightforward,+powerful,+and+convenient+combination+for+analysis+of+air-sensitive+organometallics.">Coupling an electrospray ionization mass spectrometer with a glovebox: A straightforward, powerful, and convenient combination for analysis of air-sensitive organometallics.</a> Organometallics. 27, 3303-3306 (2008).</li><li>Cooper, G. J. T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structural+and+Compositional+Control+in+{M12}+Cobalt+and+Nickel+Coordination+Clusters+Detected+Magnetochemically+and+with+Cryospray+Mass+Spectrometry.">Structural and Compositional Control in {M12} Cobalt and Nickel Coordination Clusters Detected Magnetochemically and with Cryospray Mass Spectrometry.</a> Angewandte Chemie International Edition. 46, 1340-1344 (2007).</li><li>Wang, W. S., Tseng, P. W., Chou, C. H., Shiea, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Detection+of+reactive+1,2,3-hexatriene-5-one+monomer+by+low-temperature+atmospheric+pressure+ionization+mass+spectrometry.">Detection of reactive 1,2,3-hexatriene-5-one monomer by low-temperature atmospheric pressure ionization mass spectrometry.</a> Rapid Communications in Mass Spectrometry. 12, 931-934 (1998).</li><li>Wang, C. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Detection+of+a+thermally+unstable+intermediate+in+the+Wittig+reaction+using+low-temperature+liquid+secondary+ion+and+atmospheric+pressure+ionization+mass+spectrometry.">Detection of a thermally unstable intermediate in the Wittig reaction using low-temperature liquid secondary ion and atmospheric pressure ionization mass spectrometry.</a> Journal of the American Society for Mass Spectrometry. 9, 1168-1174 (1998).</li><li>Eelman, M. D., Blacquiere, J. M., Moriarty, M. M., Fogg, D. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Shining+new+light+on+an+old+problem:+Retooling+MALDI+mass+spectrometry+for+organotransition-metal+catalysis.">Shining new light on an old problem: Retooling MALDI mass spectrometry for organotransition-metal catalysis.</a> Angewandte Chemie-International Edition. 47, 303-306 (2008).</li><li>Linden, H. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Liquid+injection+field+desorption+ionization:+a+new+tool+for+soft+ionization+of+samples+including+air-sensitive+catalysts+and+non-polar+hydrocarbons.">Liquid injection field desorption ionization: a new tool for soft ionization of samples including air-sensitive catalysts and non-polar hydrocarbons.</a> Eur. J. Mass Spectrom. 10, 459-468 (2004).</li><li>Gross, J. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Liquid+injection+field+desorption/ionization+of+reactive+transition+metal+complexes.">Liquid injection field desorption/ionization of reactive transition metal complexes.</a> Analytical and Bioanalytical Chemistry. 386, 52-58 (2006).</li><li>Peterson, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mass+Spectrometer+All-Glass+Heated+Inlet.">Mass Spectrometer All-Glass Heated Inlet.</a> Analytical Chemistry. 34, 1850-1851 (1962).</li><li>Stafford, C., Morgan, T. D., Brunfeldt, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+mass+spectrometer+all-glass+heated+inlet.">A mass spectrometer all-glass heated inlet.</a> International Journal of Mass Spectrometry and Ion Physics. 1, 87-92 (1968).</li><li>Hayes, S. A., Berger, R. J. F., Mitzel, N. W., Bader, J., Hoge, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chlorobis(pentafluoroethyl)phosphane:+Improved+Synthesis+and+Molecular+Structure+in+the+Gas+Phase.">Chlorobis(pentafluoroethyl)phosphane: Improved Synthesis and Molecular Structure in the Gas Phase.</a> Chemistry-a European Journal. 17, 3968-3976 (2011).</li><li>Zakharov, A. V., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functionalized+Bis(pentafluoroethyl)phosphanes:+Improved+Syntheses+and+Molecular+Structures+in+the+Gas+Phase.">Functionalized Bis(pentafluoroethyl)phosphanes: Improved Syntheses and Molecular Structures in the Gas Phase.</a> European Journal of Inorganic Chemistry. , 3392-3404 (2013).</li></ol>

The acquisition of mass spectra from compounds which decompose under standard sample preparation procedures is presented in this protocol. The presented technique is designed for the analysis of metal organyls, silanes and phosphane, which are highly susceptible to oxidation and/or hydrolysis, making it interesting especially for inorganic chemists. In order to achieve optimal results, vacuum or air-free conditions have to be preserved throughout the analysis. Therefore the protocol should be followed meticulously. In ca...

The analysis of compounds, such as metal organyls, silanes, or phosphanes by mass spectrometry is not always feasible. Several of these compounds are known to decompose rapidly when in contact with air. Therefore the most crucial steps when measuring mass spectra are sample preparation, the transfer of the analyte into the mass spectrometer and ion generation in the absence of air. In this protocol, we describe a strategy to meet these requirements and present an inlet system, which makes it possible to obtain mass spectra of volatile compounds previously not to be analyzed by mass spectrometry due to their difficult handling and rapid decomposition under ambient conditions. Thereby, unambiguous identification of novel or existing volatile metal organyls, silanes and phosphanes, susceptible to oxidation or hydrolysis, can now be performed with the assistance of mass spectrometry. There are two requirements which have to be met in order to analyze compounds which are susceptible to oxidation or hydrolysis: sample preparation and ion generation under inert conditions. The last premise can be easily met using a mass spectrometer with an ion source operating under vacuum. This is the case with most matrix-assisted-laser-desorption/ionization (MALDI) mass spectrometers and with all electron impact ionization (EI) mass spectrometers1,2. Electrospray ionization (ESI) is not readily compatible for the analysis of compounds susceptible to oxidation or hydrolysis, as the ionization process takes place under ambient conditions3. However, for some compounds which react not vigorously with oxygen or water, the drying and nebulizing gas with which most ESI sources are operated is sufficient for analysis by mass spectrometry4. This is also the case for Ionization strategies similar to ESI, e.g., low-temperature ESI, low-temperature atmospheric pressure ionization, and low-temperature liquid secondary ion mass spectrometry5-7. In contrast, sample preparation and transfer into the ion source under inert conditions is much more challenging. Both MALDI and ESI instruments have been coupled with glove boxes in order to enable sample preparation of compounds susceptible to oxidation and/or hydrolysis in an inert atmosphere4,8. The mass spectrometer is interfaced to the glove box either with a transfer capillary (ESI) or directly attached to the glove box (MALDI). The coupling of a glove box to a mass spectrometer via a transfer capillary would also be possible using another ionization strategy &#8211; liquid injection field desorption/ionization (LIFDI) &#8211; with which the analysis of sensitive compounds was reported9,10.
Additionally, MALDI and LIFDI are not suitable for the analysis of highly volatile compounds. MALDI requires the co-crystallization of the analyte with a matrix and LIFDI requires the deposition of the analyte onto an emitter from a solution. With both ionization strategies it is very likely that the analyte will evaporate along with the solvent. In contrast to MALDI instruments, EI mass spectrometers usually offer several methods for introducing the sample into the ion source: the direct inlet probe (small amounts of solids, oils, or waxes are deposited into an aluminum crucible which is introduced using a push rod), a septum inlet (for liquids), or coupling with a gas chromatograph. Again, at least part of the sample transfer takes place under ambient conditions and is difficult to perform under an inert atmosphere.
In the 1960&#8217;s, a sample inlet system was presented which enables the introduction of samples under vacuum into the ion source of an EI instrument &#8211; the all-glass heated inlet system (AGHIS)11,12. Here, the sample was located inside a sealed piece of glass capillary, which was inserted into the AGHIS. Subsequently, the AGHIS was evacuated and the glass container with the sample was broken. The AGHIS was then heated to evaporate the sample which reached the ion source of an EI mass spectrometer by means of a leak. When the glass capillary with the sample was prepared inside a glove box, the sample could be introduced into the mass spectrometer without any contact to air. However, the AGHIS is an apparatus which is not commercially available and difficult to assemble even for a skilled glassblower workshop. Due to the large dimensions switching between direct inlet using a push rod and AGHIS is not straight forward.
In our mass spectrometry lab, we developed a similar inlet system in the style of the AGHIS. However, as it is not possible to heat the inlet system, the analyte has to exhibit a certain volatility in order to enter the ion source of the mass spectrometer. The volatility of the analyte has to be sufficient, to allow for the transfer of the compound under vacuum at liquid nitrogen temperature &#8211; either by boiling or sublimation. The custom-made inlet system consists of a stainless steel plate, which is positioned at the direct inlet system, a stainless steel tube with a needle valve, and a flange, to which a lockable test tube containing the sample can be attached. The installation of the cold inlet system requires no modifications to the mass spectrometer (Autospec X, Vacuum Generators, now Waters Corp., Manchester, UK) &#8211; switching between cold inlet system and direct inlet using a push rod can be performed easily within seconds.
The presented inlet system is of particular use when metal organyls, silanes, or phosphanes, susceptible to oxidation or hydrolysis, have to be analyzed. These compounds are commonly analyzed using nuclear magnetic resonance (NMR) spectroscopy or&#160;infrared (IR) spectroscopy. Unfortunately, these methods allow not always for an unambiguous identification of a compound because they yield incomplete information, e.g., when elements such as chlorine or bromine are part of the molecule. Gas electron diffraction on the other hand is able to provide detailed information about the analyte, however, the method is very time consuming, sample preparation is difficult, and only few groups are able to conduct these analysis13,14. Here, the cold inlet system for the analysis of metal organyls, silanes, or phosphanes, susceptible to oxidation or hydrolysis by EI mass spectrometry is of great use for (in)organic chemists enabling the unambiguous identification of novel compounds by supplying them with information regarding the mass of a molecule and of characteristic fragment ions. The only prerequisite for the measurement of mass spectra for a substance is a certain volatility at reduced pressure.

<table border="0" cellpadding="0" cellspacing="0" width="971">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:311px;">Name of Reagent/Material</td>
			<td style="width:71px;">Company</td>
			<td style="width:155px;">Catalog Number</td>
			<td style="width:435px;">Comments</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:311px;">VG Autospec X</td>
			<td colspan="2">Micromass Co. UK Ltd (now Waters)</td>
			<td style="width:435px;">other EI mass spectrometers with direct inlet using a push rod should also be compatible with this technique</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:311px;">Lockable test tubes with flange</td>
			<td style="width:71px;">-</td>
			<td style="width:155px;">-</td>
			<td style="width:435px;">costum made, teflon tap should be used for locking the test tube</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:311px;">Interface for lockable test tubes</td>
			<td style="width:71px;">-</td>
			<td style="width:155px;">-</td>
			<td style="width:435px;">costum made , interface is prepared from stainless steel. Needle valve has to be included into the interface-design!</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:311px;">Schlenk line</td>
			<td style="width:71px;">-</td>
			<td style="width:155px;">-</td>
			<td style="width:435px;">costum made, has to include vacuum pump for evacuation of thest tubes and cold trap with liquid nitrogen for trapping of the sample</td>
		</tr>
	</tbody>
</table>

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.

An EI mass spectrum of tris(trifluoromethyl)phosphane is presented in Figure 3, a compound, which decomposes rapidly when in contact with air (Figure 4). The presented interface allows for the straight forward measurement of mass spectra for these compounds. The operation of the novel interface is easy and fast and presents no obstacle when operating the mass spectrometer with the routinely applied direct inlet using the push rod.
<p class="jove_content" fo:keep-together.within-page=...

Watch this Scientific Journal Video about Analysis of Volatile and Oxidation Sensitive Compounds Using a Cold Inlet System and Electron Impact Mass Spectrometry at JoVE.com

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 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 ...

Research

JoVE Journal

Chemistry

Untargeted Metabolomics from Biological Sources Using Ultraperformance Liquid Chromatography-High Resolution Mass Spectrometry (UPLC-HRMS)

Untargeted Metabolomics from Biological Sources Using Ultraperformance Liquid Chromatography-High Resolution Mass Spectrometry UPLC-HRMS

Here we present a workflow to analyze the metabolic profiles for biological samples of interest including; cells, serum, or tissue. The sample is first ...

Visualization of Ambient Mass Spectrometry with the Use of Schlieren Photography

This manuscript outlines how to visualize mass spectrometry ambient ionization sources using schlieren photography. In order to properly optimize the mass ...

Rapid High-throughput Species Identification of Botanical Material Using Direct Analysis in Real Time High Resolution Mass Spectrometry

We demonstrate that direct analysis in real time-high resolution mass spectrometry can be used to produce mass spectral profiles of botanical material, ...

Analyzing the Photo-oxidation of 2-propanol at Indoor Air Level Concentrations Using Field Asymmetric Ion Mobility Spectrometry

We demonstrate a versatile protocol to be used for determining the effectiveness of photocatalysts in degrading indoor air concentration (ppb) volatile ...

Fizzy Extraction of Volatile Organic Compounds Combined with Atmospheric Pressure Chemical Ionization Quadrupole Mass Spectrometry

Chemical analysis of volatile and semivolatile compounds dissolved in liquid samples can be challenging. The dissolved components need to be brought to ...

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 ...

Synthesis and Mass Spectrometry Analysis of Oligo-peptoids

Peptoids are sequence-controlled peptide-mimicking oligomers consisting of N-alkylated glycine units. Among many potential applications, peptoids have ...

High-throughput and Comprehensive Drug Surveillance Using Multisegment Injection-Capillary Electrophoresis-Mass Spectrometry

New analytical methods are urgently needed to enable high-throughput, yet comprehensive drug screening, given an alarming opioid and prescription drug ...

Ion Mobility-Mass Spectrometry Techniques for Determining the Structure and Mechanisms of Metal Ion Recognition and Redox Activity of Metal Binding Oligopeptides

Electrospray ionization (ESI) can transfer an aqueous-phase peptide or peptide complex to the gas-phase while conserving its mass, overall charge, ...

Capillary Electrophoresis-based Hydrogen/Deuterium Exchange for Conformational Characterization of Proteins with Top-down Mass Spectrometry

Resolving conformational heterogeneity of multiple protein states that coexist in solution remains one of the main obstacles in the characterization of ...