{"id":4,"date":"2024-04-04T04:31:14","date_gmt":"2024-04-04T01:31:14","guid":{"rendered":"https:\/\/sisu.ut.ee\/heritage-analysis\/52-mass-spectrometry\/"},"modified":"2024-07-18T03:36:06","modified_gmt":"2024-07-18T00:36:06","slug":"52-mass-spectrometry","status":"publish","type":"page","link":"https:\/\/sisu.ut.ee\/heritage-analysis\/52-mass-spectrometry\/","title":{"rendered":"5.2. Mass spectrometry"},"content":{"rendered":"<div style=\"height:30px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\"><span style=\"color: #b22222;\">1. General aspects of mass spectrometry<\/span><\/h2>\n\n\n\n<p>Mass spectrometry (MS)  is a <strong>highly selective<\/strong> and <strong>sensitive<\/strong> analytical technique that is used for the <strong>qualitative<\/strong> and <strong>quantitative analysis<\/strong> of a wide variety of materials. In MS, sample compounds are converted into gas-phase ions and their <strong>mass-to-charge (<em>m\/z<\/em>) ratios<\/strong> of those ions are measured. Mass spectrometry can be used as a standalone technique (direct MS) or combined with chromatographic techniques (GC-MS, LC-MS).[1]<\/p>\n\n\n\n<p><\/p><div class=\"ratio ratio-16x9 mb-3\"><div class=\"video-placeholder-wrapper video-placeholder-wrapper--16x9\">\n\t\t\t    <div class=\"video-placeholder d-flex justify-content-center align-items-center\">\n\t\t\t        <div class=\"overlay text-white p-2 w-100 text-center d-block justify-content-center align-items-center\">\n\t\t\t            <div>To view third-party content, please accept cookies.<\/div>\n\t\t\t            <button class=\"btn btn-secondary btn-sm mt-1 consent-change\">Change consent<\/button>\n\t\t\t        <\/div>\n\t\t\t    <\/div>\n\t\t\t<\/div>\n<\/div>\n\n\n\n<p>In the MS instrument, the sample molecules are ionised in the <strong>ion source<\/strong> (via strong electric fields or\u00a0by bombarding the molecules with electrons, photons, or other molecules\/ions) and guided to the <strong>mass analyser<\/strong>, where the ions are sorted according to their <em>m\/z<\/em> ratios.\u00a0The sorting of the ions requires high vacuum conditions: the pressure is\u00a0in the range of 10-5 \u2026 10-10 bar, depending on the instrument type. Vacuum is required to minimise the risk of losing the created ions as a result of collisions with air molecules. The high vacuum is achieved with a series of vacuum pumps. After \u201csorting\u201d ions in the mass analyser, the separated ion packages are detected by the detector. The collected data is presented as a <strong>mass spectrum<\/strong> \u2013 a plot of ion abundance vs <em>m\/z<\/em> ratio. In Fig 1. a schematic drawing of MS instrument is presented. [1,2]<\/p>\n\n\n\n<figure class=\"wp-block-image aligncenter size-large is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"700\" src=\"https:\/\/sisu.ut.ee\/wp-content\/uploads\/sites\/285\/Fig1_MS-1024x700.png\" alt=\"\" class=\"wp-image-927\" style=\"width:869px;height:auto\" srcset=\"https:\/\/sisu.ut.ee\/wp-content\/uploads\/sites\/285\/Fig1_MS-1024x700.png 1024w, https:\/\/sisu.ut.ee\/wp-content\/uploads\/sites\/285\/Fig1_MS-300x205.png 300w, https:\/\/sisu.ut.ee\/wp-content\/uploads\/sites\/285\/Fig1_MS-768x525.png 768w, https:\/\/sisu.ut.ee\/wp-content\/uploads\/sites\/285\/Fig1_MS.png 1152w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\"><figcaption class=\"wp-element-caption\">Fig. 1. Overall scheme of a mass spectrometer and formation of a mass spectrum.<\/figcaption><\/figure>\n\n\n\n<h2 class=\"wp-block-heading has-text-align-left\"><span style=\"color: #b22222;\"><em>Ion sources<\/em><\/span><\/h2>\n\n\n\n<div class=\"wp-block-group is-vertical is-layout-flex wp-container-core-group-is-layout-8cf370e7 wp-block-group-is-layout-flex\">\n<p>The selection of different ion sources is extensive. Ion sources can be divided into <strong>soft<\/strong> and <strong>hard<\/strong>. In the case of <strong>hard ionisation<\/strong>, the energy transferred to the analysed molecules during ionisation\u00a0is high. This causes extensive fragmentation of the formed molecular ions M<sup>+<\/sup> \u2013 ions formed via removing an electron from the initial molecule M. The molecular ions are chopped into smaller fragments during ionisation. This leads to a complex mass spectrum with several peaks that contains structural information about the sample components. The most common hard ionisation technique is<strong> electron ionisation (EI)<\/strong>, which is widely used in GC-MS systems. [1,2]<\/p>\n\n\n\n<p>The majority of the ion sources are <strong>soft ion<\/strong>\u00a0sources. This means that the energy transferred to the sample molecules M during the ionisation is rather low and therefore, the\u00a0 formed ions do not\u00a0fragment extensively.\u00a0These ion sources can produce either positive or negative ions, depending on the source polarity chosen by the operator. Ions are formed mostly by protonation [M+H]<sup>+<\/sup>, cation (e.g., Na<sup>+<\/sup>) addition [M+Na]<sup>+<\/sup> or by deprotonation [M-H]<sup>\u2013<\/sup>. These ions are called <strong>quasimolecular ions<\/strong> (protonated\/deprotonated) and adduct ions (addition of a cation)\u00a0and are the ones typically observed in mass spectra (typically no fragmentation occus). Examples of soft ionisation methods are <strong>electrospray ionisation (ESI)<\/strong>, <strong>atmospheric pressure chemical ionisation (APCI)<\/strong>, <strong>chemical ionisation (CI)<\/strong>, and <strong>matrix-assisted laser desorption\/ionisation (MALDI)<\/strong>.\u00a0The applicability of ion sources depends first of all on the sample phase \u2013 gas, liquid or solid. The suitability of an ion source depends on the sample (molecule mass, polarity, solubility, volatility, etc.) and the type of information required.<\/p>\n<\/div>\n\n\n\n<p><\/p>\n\n\n\n<p>\u00a0<strong>Commonly used ion sources <\/strong>[1,2]:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong style=\"font-size: revert; text-align: var(--bs-body-text-align);\">Electron ionisation (EI)<\/strong><span style=\"font-size: revert; font-weight: var(--bs-body-font-weight); text-align: var(--bs-body-text-align);\"> is mostly used with GC-MS. Sample molecules (M) in gas phase are ionised by bombarding with high-energy electrons and at first <\/span><strong style=\"font-size: revert; text-align: var(--bs-body-text-align);\">molecular ions<\/strong><span style=\"font-size: revert; font-weight: var(--bs-body-font-weight); text-align: var(--bs-body-text-align);\">\u00a0<\/span><strong style=\"font-size: revert; text-align: var(--bs-body-text-align);\">M<sup>+<\/sup><\/strong><span style=\"font-size: revert; font-weight: var(--bs-body-font-weight); text-align: var(--bs-body-text-align);\">\u00a0are formed. These ions then fragment into smaller ions.\u00a0EI operates in a vacuum. Sample can be introduced as liquid, gas or solid (needs heating) in the EI source. EI can ionise virtually all compounds, has good ionisation efficiency, good sensitivity and the fragmentation pattern gives information about the structure of the compounds. However, <\/span>in case<span style=\"font-size: revert; font-weight: var(--bs-body-font-weight); text-align: var(--bs-body-text-align);\"> of extensive fragmentation, the molecular ion may not be observed, which complicates identification. Also, the EI mass spectrum is complex and for interpretation, reference mass spectra (library) are often needed. With EI, different oils, resins, hydrocarbons, aromatic compounds etc., can be analysed.<\/span><\/li>\n<\/ul>\n\n\n\n<div style=\"height:0px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong style=\"font-size: revert; text-align: var(--bs-body-text-align);\">Chemical ionisation (CI)<\/strong><span style=\"font-size: revert; font-weight: var(--bs-body-font-weight); text-align: var(--bs-body-text-align);\"> is also mostly used with GC-MS. <\/span>Sample compounds in gas-phase are ionised by the reaction with gas-phase ions (e.g. protonated methane CH5<sup>+<\/sup>)<span style=\"font-size: revert; font-weight: var(--bs-body-font-weight); text-align: var(--bs-body-text-align);\">. Mostly [M+H]<\/span><sup style=\"font-weight: var(--bs-body-font-weight); text-align: var(--bs-body-text-align);\">+<\/sup><span style=\"font-size: revert; font-weight: var(--bs-body-font-weight); text-align: var(--bs-body-text-align);\"> ions are formed. CI operates in a vacuum.\u00a0Little if any fragmentation occurs in CI, and thus, the mass spectrum is much simpler than in the case of EI. Also, a limited amount of structural information is obtained. With CI, lipids, amino acids, carbohydrates, etc., can be analysed.<\/span><\/li>\n<\/ul>\n\n\n\n<div style=\"height:0px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Electrospray ionisation (ESI)<\/strong> is compatible with LC-MS and can also be used with direct MS. A sample solution is sprayed into the electric field in ion source where the charged droplets are created. The solvent is gradually evaporated until gas-phase ions, typically [M+H]<sup>+<\/sup> or [M-H]<sup>\u2013<\/sup>, are formed. This source operates at atmospheric pressure. With ESI, preferably more polar compounds, especially those that have basic or acidic properties, are ionised. The sample must be completely soluble in a volatile solvent or a volatile solvent mixture. It is a very soft and sensitive ionisation method and is suitable for determining compounds at very low concentrations. Compounds with very high molecular mass (approx. 100000 Da) can be analysed. The disadvantages of ESI are that the sample must be fully dissolved \u2013 only soluble part of the sample can be analysed (which is an advantage in the case of LC), reproducibility is not always good, and compounds can suppress each other\u2019s ionisation (e.g., matrix effects). With ESI, proteins, carbohydrates, lipids, amino acids, polymers, etc., can be analysed.<\/li>\n<\/ul>\n\n\n\n<div style=\"height:0px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Atmospheric pressure chemical ionisation (APCI)<\/strong> is compatible with LC-MS, direct MS. The sample is introduced as liquid and sprayed into the source. The solvent evaporates and the compounds are converted to gas phase molecules by heat. The molecules are ionised by the reaction with ionic species created by the corona discharge. APCI operates at atmospheric pressure. With APCI, low to medium polarity compounds can be ionised. With APCI sample must be thermally stable and must be completely soluble in a volatile solvent. It is a soft and\u00a0sensitive ionisation method, has quite high ionisation efficiency and compounds do not suppress each other\u2019s (at least not so much as with ESI). It is suitable for samples with low analyte concentrations and different lipids, amino acids, resins, carbohydrates, etc., can be analysed.<\/li>\n<\/ul>\n\n\n\n<div style=\"height:0px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Matrix-assisted laser desorption\/ionisation (MALDI)<\/strong> is\u00a0compatible with direct LRMS and\u00a0HRMS but not with LC-MS. MALDI is based on the desorption of a solid mixture of matrix substance and sample molecules and their ionisation by laser radiation whereby the matrix substance helps to ionise the sample molecules. Common matrix materials used in positive mode are dihydroxybenzoic acid (DHB), \u03b1-cyano-4-hydroxycinnamic acid (CHCA), sinapic acid (SA) and in negative mode pyridines, 3-aminoacridine (3-AA) and 9-aminoacridine (9-AA). MALDI enables the determination of compounds from very small samples (0.1 mg or even less) dissolved in a solvent (the sample does not need to be fully soluble) or just by implementing direct analysis, i.e. without dissolution and\/or derivatisation of the sample. With MALDI, different complex, non-volatile, highly oxidized, non-soluble, and polymeric samples can be analysed. [3]<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\"><span style=\"color: #b22222;\"><em>Mass analysers<\/em><\/span><\/h2>\n\n\n\n<div class=\"wp-block-group is-vertical is-layout-flex wp-container-core-group-is-layout-8cf370e7 wp-block-group-is-layout-flex\">\n<p>The heart of a MS instrument is the mass analyser that separates the ions according to their <em>m\/z<\/em> values. The separation is achieved by applying electric and\/or magnetic fields to the formed ions. Mass analysers can be divided according to <strong>resolution<\/strong>. <strong>Low resolution (LR) MS<\/strong> instruments are, for example,\u00a0<strong>quadrupole (Q)<\/strong> and <strong>ion trap (IT)<\/strong>. <strong>High resolution (HR) MS<\/strong> devices are for example <strong>Fourier Transform Ion Cyclotron Resonance mass spectrometry<\/strong> (<strong>FT-ICR-MS)<\/strong> and\u00a0\u00a0<strong>Fourier Transform orbitrap\u00a0(FT-OT)<\/strong>. <strong>Time of Flight (ToF) <\/strong>can be classified as LR or HR depending on the specific configuration. [1,2]<\/p>\n\n\n\n<p><span lang=\"EN-GB\">Mass analysers (same type or different) can be also combined. These instruments are called <strong>tandem<\/strong> or <strong>hybrid or MS\/MS instruments<\/strong> and they allow to do mass analysis in at least two stages. Nowadays, several tandem MS configurations are available, but the most common is the\u00a0<strong>triple quadrupole mass spectrometer<\/strong> (<strong>TQMS<\/strong> or <strong>QQQ MS<\/strong>), where the first and third quadrupole mass analysers are used for selecting the ions and second quadrupole (nowadays also hexapole or octapole) is used for fragmenting the initial ions.<\/span><span lang=\"EN-GB\">\u00a0<\/span><\/p>\n\n\n\n<p>In Table 1 comparison of different mass analysers are presented.<\/p>\n<\/div>\n\n\n\n<p>\u00a0<\/p>\n\n\n\n<div class=\"wp-block-group is-vertical is-layout-flex wp-container-core-group-is-layout-8cf370e7 wp-block-group-is-layout-flex\">\n<p>Table 1. Comparison of mass analysers used for the analysis of cultural heritage materials.\u00a0[3-5]<\/p>\n\n\n\n<figure class=\"wp-block-table has-small-font-size\"><table class=\"table table-hover\"><thead><tr><th class=\"has-text-align-center\" data-align=\"center\"><strong>Mass analyzer<\/strong><\/th><th><strong>Quadrupole (Q)<\/strong><\/th><th class=\"has-text-align-left\" data-align=\"left\"><strong>Ion trap (IT)<\/strong><\/th><th class=\"has-text-align-left\" data-align=\"left\"><strong>Time of Flight (ToF)<\/strong><\/th><th><strong>FT-ICR-MS<\/strong><\/th><th class=\"has-text-align-left\" data-align=\"left\"><strong>FT-OT-MS<\/strong><\/th><\/tr><\/thead><tbody><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Basic principle<\/strong><\/td><td>\u2013 Ion separation obtained by using electric field.<br>\u2013 Often used also as tandem instrument with three consecutive quadrupoles (QQQ, triple quad).<br>\u2013 Can be combined with IT, ToF.<\/td><td class=\"has-text-align-left\" data-align=\"left\">\u2013 Ions are separated by trapping them in an electric field and applying varying potential.<br>\u2013 Can be combined with other mass analysers (Q, ToF, FT-ICR).<\/td><td class=\"has-text-align-left\" data-align=\"left\">\u2013 Ions are accelerated and directed to a field-free zone where the ions are separated in time \u2192 ions with smaller m\/z reach the detector faster.<br>\u2013 Mostly reflectron (refl.) instruments are used \u2192 the filed-free zone is longer.<br>\u2013 Can be combined with ToF, Q, IT.<\/td><td>\u2013 Ions are separated in magnetic field based on their cyclotron frequencies.<br>\u2013 Can be combined with other mass analyzers (Q, IT).<\/td><td class=\"has-text-align-left\" data-align=\"left\">Ions are separated in the electric field according to their cyclotron frequencies.<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Resolution<\/strong><br><a href=\"https:\/\/sisu.ut.ee\/wp-content\/uploads\/sites\/285\/resolution_1.pdf\" target=\"_blank\" rel=\"noreferrer noopener\">more info<\/a><\/td><td>Low (2000)<\/td><td class=\"has-text-align-left\" data-align=\"left\">Low\u00a0(4000)<\/td><td class=\"has-text-align-left\" data-align=\"left\">ToF, <em>linear<\/em>: 5000 (low); <br>ToF <em>refl.<\/em>: 30000 (high)<\/td><td>Very high (500000)<\/td><td class=\"has-text-align-left\" data-align=\"left\">Very high (100000)<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong><em>m\/z<\/em> accuracy<\/strong><br><a href=\"https:\/\/sisu.ut.ee\/wp-content\/uploads\/sites\/285\/m_z_accuracy_2.pdf\" target=\"_blank\" rel=\"noreferrer noopener\">more info<\/a><\/td><td>Low (100 ppm)<\/td><td class=\"has-text-align-left\" data-align=\"left\">Low (100 ppm)<\/td><td class=\"has-text-align-left\" data-align=\"left\">ToF, <em>linear<\/em>: 200 ppm;<br>ToF <em>refl.<\/em>: 10 ppm<\/td><td>Very high (~1 ppm)<\/td><td class=\"has-text-align-left\" data-align=\"left\">Very high (&lt;5 ppm)<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong><em>m\/z<\/em> range<\/strong><\/td><td>Up to <em>m\/z<\/em> 4000<\/td><td class=\"has-text-align-left\" data-align=\"left\">Up to <em>m\/z<\/em> 6000<\/td><td class=\"has-text-align-left\" data-align=\"left\">ToF, <em>linear<\/em>: <em>m\/z <\/em>&gt;1000000; <br>ToF <em>refl.<\/em>: <em>m\/z<\/em> 10000<\/td><td>Up to <em>m\/z<\/em> 100000<\/td><td class=\"has-text-align-left\" data-align=\"left\">Up to <em>m\/z<\/em> 50000<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Advantages<\/strong><\/td><td>\u2013 Easy to use.<br>\u2013 Very good detection limits.<br>\u2013 Quite small and low-cost instrument.<br>\u2013 Very good sensitivity for specifically selected ions.<br>\u2013 Good compatibility with ESI, APCI, EI, CI.<br>\u2013 Can be coupled with GC and LC.<\/td><td class=\"has-text-align-left\" data-align=\"left\">\u2013 Quite small and low-cost instrument.<br>\u2013 Relatively easy to use.<br>\u2013 High sensitivity.<br>\u2013 Good stability \u2192 mass spectra are reproducible.<br>\u2013 Compatible with ESI, APCI, EI, CI, MALDI.<br>\u2013 Can be coupled with GC and LC.<\/td><td class=\"has-text-align-left\" data-align=\"left\">\u2013 Quick \u2013 the ions are scanned rapidly.<br>\u2013 Medium-cost instrument with a relatively simple design.<br>\u2013 High sensitivity.<br>\u2013 Good compatibility with MALDI.<br>\u2013 Can be used with EI, CI.<br>\u2013 Can be coupled with GC and LC.<\/td><td>\u2013 Highest m\/z accuracy and resolution.<br>\u2013 Good sensitivity.<br>\u2013 Very good for identifying complex materials.<br>\u2013 Good compatible with ESI, APCI, MALDI, EI, CI sources.<br>\u2013 Can be coupled with GC and LC.<\/td><td class=\"has-text-align-left\" data-align=\"left\">\u2013 Offers very good <em>m\/z<\/em> accuracy and resolution.<br>\u2013 Very good for identifying complex materials.<br>\u2013 Compatible with ESI, APCI, MALDI, EI, CI source.<br>\u2013 Can be coupled with GC and LC.<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Disadvantages<\/strong><\/td><td>\u2013 Not suited for pulsed ion sources: MALDI.<br>\u2013 Modest sensitivity for scanning all ions in a wider <em>m\/z <\/em>range.<\/td><td class=\"has-text-align-left\" data-align=\"left\">Ions are collected into the cell \u2192 overload of ions may occur which decreases the resolution.<\/td><td class=\"has-text-align-left\" data-align=\"left\">More sophisticated equipment (HR ToF) is more expensive and requires skilled operator.<\/td><td>\u2013 The superconducting magnet makes the instrument big and expensive.<br>\u2013 Complex device.<br>\u2013 Requires very high vacuum (n x 10-10 bar).<\/td><td class=\"has-text-align-left\" data-align=\"left\">Requires very high vacuum (n x 10-10 bar).<\/td><\/tr><\/tbody><\/table><\/figure>\n<\/div>\n\n\n\n<p><\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span style=\"color: #b22222;\"><em>Detectors<\/em><\/span><\/h2>\n\n\n\n<p>After sorting all the ions according to their m\/z values, they are detected. This is usually done by converting the ions into electrical signals by an ion transducer. The more traditional detectors in mass spectrometry are the electron multiplier (the most widely used detector in different LR mass spectrometers, such as Q and QQQ, IT, ToF, etc.). For FT-ICR-MS and FT-OT-MS a different approach is used for detecting the ions. The ions are detected by detection plates that register the so-called image\u00a0current that the ions produce while oscillating between these plates.<span style=\"font-size: 11.6667px;\">\u00a0<\/span>[1,2]<\/p>\n\n\n\n<p>\u00a0<\/p>\n\n\n\n<p><span style=\"font-size: 16px;\"><strong>Further reading<\/strong><\/span><\/p>\n\n\n\n<p>More information can be found on the University of Bristol, School of Chemistry Mass Spectrometry Facility web page:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>about ion sources: http:\/\/www.chm.bris.ac.uk\/ms\/ionisation.xhtml<\/li>\n\n\n\n<li>about mass analysers:\u00a0<a title=\"\" href=\"http:\/\/www.chm.bris.ac.uk\/ms\/analysis.xhtml\" data-url=\"http:\/\/www.chm.bris.ac.uk\/ms\/analysis.xhtml\">http:\/\/www.chm.bris.ac.uk\/ms\/analysis.xhtml\u00a0<\/a><\/li>\n<\/ul>\n\n\n<p><\/p><div class=\"accordion mb-3\">\n        <div class=\"accordion-item accordion-item--white\">\n        <h2 class=\"accordion-header\" id=\"accordion-69d9f0b6e5f71-heading\">\n            <button class=\"accordion-button collapsed\" type=\"button\" data-bs-toggle=\"collapse\" data-bs-target=\"#accordion-69d9f0b6e5f71-collapse\" aria-expanded=\"true\" aria-controls=\"accordion-69d9f0b6e5f71-collapse\"><span style=\"font-size: 16px;\"><strong>References<\/strong> (click here)<\/span><\/button>\n        <\/h2>\n        <div id=\"accordion-69d9f0b6e5f71-collapse\" class=\"accordion-collapse collapse\" aria-labelledby=\"accordion-69d9f0b6e5f71-heading\">\n            <div class=\"accordion-body\">\n<ol>\n<li>de Hoffmann, E.; Stroobant, V. <em>Mass Spectrometry: Principles and Applications<\/em>, 3rd ed.; John Wiley &amp; Sons, Ltd.: Chichester, UK, 2007.<\/li>\n<li>Gross, J. H. <em>Mass Spectrometry: A Textbook<\/em>, 3rd ed.; Springer International Publishing: Switzerland, 2017.<\/li>\n<li>Colombini, M. P.; Modugno, F. <em>Organic Mass Spectrometry in Art and Archaeology<\/em>; John Wiley &amp; Sons, Ltd.: Chichester, UK, 2009.<\/li>\n<li>Mazzeo, R.<em> Analytical Chemistry for Cultural Heritage<\/em>; Springer International Publishing: Switzerland, 2016.<\/li>\n<li>Teearu, A. <em>Development of MALDI-FT-ICR-MS Methodology for the Analysis of Resinous Materials<\/em>, PhD thesis; University of Tartu Press: Tartu, Estonia, 2017.<\/li>\n<\/ol>\n<p><\/p><\/div>\n        <\/div>\n        <\/div>\n    <\/div>\n\n\n\n<p>The slides used in the video can be downloaded from\u00a0here:<\/p>\n\n\n\n<div class=\"wp-block-group attached-files-group is-layout-constrained wp-block-group-is-layout-constrained\">\n<div class=\"wp-block-file\"><a id=\"wp-block-file--media-e67fa8e6-7bdd-453e-a787-c8ea58d71fcc\" href=\"https:\/\/sisu.ut.ee\/wp-content\/uploads\/sites\/285\/general_aspects_of_ms.pdf\" target=\"_blank\" rel=\"noreferrer noopener\">General_aspects_of_MS.pdf<\/a><\/div>\n\n\n\n<div class=\"wp-block-file\"><a id=\"wp-block-file--media-90659cf2-ce0c-4537-8e94-70895ff805c2\" href=\"https:\/\/sisu.ut.ee\/wp-content\/uploads\/sites\/285\/overview_of_irms.pdf\" target=\"_blank\" rel=\"noreferrer noopener\">Overview_of_IRMS.pdf<\/a><\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>1. General aspects of mass spectrometry Mass spectrometry (MS) is a highly selective and sensitive analytical technique that is used for the qualitative and quantitative analysis of a wide variety of materials. In MS, sample compounds are converted into gas-phase &#8230;<\/p>\n","protected":false},"author":151,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_acf_changed":false,"inline_featured_image":false,"footnotes":""},"class_list":["post-4","page","type-page","status-publish","hentry"],"acf":[],"_links":{"self":[{"href":"https:\/\/sisu.ut.ee\/heritage-analysis\/wp-json\/wp\/v2\/pages\/4","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/sisu.ut.ee\/heritage-analysis\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/sisu.ut.ee\/heritage-analysis\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/sisu.ut.ee\/heritage-analysis\/wp-json\/wp\/v2\/users\/151"}],"replies":[{"embeddable":true,"href":"https:\/\/sisu.ut.ee\/heritage-analysis\/wp-json\/wp\/v2\/comments?post=4"}],"version-history":[{"count":27,"href":"https:\/\/sisu.ut.ee\/heritage-analysis\/wp-json\/wp\/v2\/pages\/4\/revisions"}],"predecessor-version":[{"id":1087,"href":"https:\/\/sisu.ut.ee\/heritage-analysis\/wp-json\/wp\/v2\/pages\/4\/revisions\/1087"}],"wp:attachment":[{"href":"https:\/\/sisu.ut.ee\/heritage-analysis\/wp-json\/wp\/v2\/media?parent=4"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}