Subscriber access provided by UNIV OF DURHAM
Technical Note
Microprobe for the thermal analysis of crude oil coupled to photoionization FTMS. Yury I. Kostyukevich, Alexander Ya. Zherebker, Mikhail s. Vlaskin, Ludmila Borisova, and Eugene N. Nikolaev Anal. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.analchem.8b02043 • Publication Date (Web): 11 Jul 2018 Downloaded from http://pubs.acs.org on July 18, 2018
Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.
Page 1 of 22 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Analytical Chemistry
1
Microprobe for the thermal analysis of crude oil
2
coupled to photoionization FTMS.
3 4
AUTHOR NAMES
5
Yury Kostyukevicha,b,c,d, Alexander Zherebkera, Mikhail S. Vlaskind, Ludmila Borisovae, and
6
Eugene Nikolaev*a,b,c
7
AUTHOR ADDRESS
8
a
9
Federation
Skolkovo Institute of Science and Technology Novaya St., 100, Skolkovo 143025 Russian
10
b
11
38 k.2, 119334 Moscow, Russia;
12
c
Moscow Institute of Physics and Technology, 141700 Dolgoprudnyi, Moscow Region, Russia
13
d
The Joint Institute for High Temperatures of Russian academy of sciences, 125412, Moscow,
14
Izhorskaya st. 13str.2, Russia
15
e
16
101000, Russia
Institute for Energy Problems of Chemical Physics Russian Academy of Sciences Leninskij pr.
National Research University Higher School of Economics, 20 Miasnitskaya Ulitsa, Moscow
ACS Paragon Plus Environment
1
Analytical Chemistry 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 2 of 22
1 2
KEYWORDS
3
Crude oil, APPI, Orbitrap, ionization, thermal desorption, kinetic.
4
ABSTRACT
5
We present the simple microprobe for the investigation of the crude oil by a thermal desorption
6
photoionization coupled to Orbitrap mass spectrometry. The droplet of crude oil was placed on
7
the heating element with controllable temperature. The temperature was linearly increased, crude
8
oil vapors were ionized by a vacuum ultraviolet (VUV) lamp and detected by Orbitrap mass
9
spectrometer. Use of modified Orbitrap allowed introduction of the heating element and VUV
10
lamp directly into the ion funnel and performing experiment not only at atmosphere pressure, but
11
also at 20 Torr, 10 Torr and 5 Torr. We have observed that at high pressure protonated CHN
12
compounds dominate in the spectrum, while at the low pressure CH compounds dominate.
13
Similar to previously reported thermogravimetry coupled to photo ionization or chemical
14
ionization mass spectrometry systems we were able to separate compounds with different
15
desorption energy and reliably detect low abundant compounds. Also, we were able to determine
16
the desorption temperature for each compound of the crude oil. We have found that temperature
17
of desorption increases linearly with m/z for compounds that belong to the same homology series
18
(same Kendrick mass defect). This may serve as indirect evidence that such compounds differ
19
only by the length of aliphatic chains attached to some basic structure.
20 21
INTRODUCTION
ACS Paragon Plus Environment
2
Page 3 of 22 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Analytical Chemistry
1
Being a most valuable resource to mankind the crude oil is investigating using most advanced
2
experimental techniques such as Thermal gravimetric analysis (TGA)1,2, X-ray photoelectron
3
spectroscopy (XPS)3, Nuclear magnetic resonance (NMR)4,5, gas and liquid chromatography (GC
4
and LC) and mass spectrometry6. High resolution mass spectrometers such as Fourier transform
5
ion cyclotron resonance mass spectrometer (FT ICR) and Orbitrap have proven to be a most
6
informative analytical tool, enabling detection of thousands of individual compounds in
7
milligram of the sample7. Introduction of dynamically harmonized FT ICR cell8 and 21-T
8
magnets shifted the limits of the resolving power by an order of magnitude and currently the
9
group of Alan Marshall holds the record of highest number of compound determined in the single
10
mass spectrum of heavy crude oil > 400 0009. Nevertheless, different compounds of crude oil are
11
present in a wide range of concentrations, so, low abundant compounds could be mistaken for
12
13
13
mass spectrometric analysis would increase the reliability of the detection.
C,
34
S isotopes or even for chemical noise, consequently, a separation of the crude oil prior to
14
For the online separation of crude oil prior to mass spectrometric analysis various systems were
15
developed: GC/GC systems10, LC systems11-13, TG systems14,15, distillation16,17. Such systems
16
could be used with various ionization methods: Atmospheric Pressure photoionization (APPI)18,
17
Atmospheric Pressure Chemical ionization (APCI)19, Electrospray (ESI)20, electron impact
18
ionization (EI); and could be coupled to various mass spectrometers: FT ICR, Orbitrap, Time-Of-
19
Flight (TOF)7,21. Previously, Boduszynski16,17 and
20
comprehensive study comparing molecular composition of different heavy petroleum distillate
21
fractions. It was demonstrated that molecular weight distribution broadens and shifts to higher
22
mass with increasing boiling point. Equations, which relates boiling points and C/H ratio to
23
molecular weight, were proposed23-25.
A. McKenna et all22 have performed a
ACS Paragon Plus Environment
3
Analytical Chemistry 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 4 of 22
1
For the insights about chemical structure and properties of individual compounds of crude oil
2
the Hydrogen/Deuterium exchange couple to high resolution mass spectrometry could be
3
used26,27. H/D exchange reaction allows enumeration of labile hydrogens in molecular ions and
4
speciation of different types of compound28-35. Recently it was demonstrated that H/D exchange
5
could be coupled to the GC-ESI-MS systems36.
6
Without challenging the merits of the powerful commercial TG-GC-MS systems for analysis of
7
crude oil, we must admit that there is a trend to the simplification of the experimental setup in
8
mass spectrometry. The rapid development of ambient mass spectrometry and introduction of
9
paper spray37 (including its application for analysis of petroleum38), leaf spray39, tissue spray40,
10
wooden tips as ESI emitters41 or thermal desorption probes42 is the characteristic example of this
11
trend. Here we describe a simple and cheap experimental setup for the TD-MS analysis of crude
12
oil. The device was build using spare parts of a regular 3D printer. The device allows not only
13
separation of crude oil based on value of the desorption temperature but determination of the
14
desorption temperature for each compound.
15
METHODS
16
Samples. A light Siberian crude oil was used for experiments. Elemental composition of the
17
sample was determined on the Thermo Scientific Flash 2000 HT analyzer and was found to be: C
18
- 85.85%, H – 12.6%, N – 0.2%, S – 1.35%, Ash – 0.0%. API gravity was 37. TAN (Total acid
19
Number) was 1.4 mg KOH/g.
20
Thermal desorption system. The design of the experimental setup is presented in the Figure
21
1.A and Figure 1B. The photo is shown in Supporting Information (Figure S1). The device was
22
build using spare parts of a regular 3D printer: the heating element, thermistor and Arduino Mega
ACS Paragon Plus Environment
4
Page 5 of 22 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Analytical Chemistry
1
+ RAMPS 1.4 shield. The RAMPS 1.4 already has all required electronics for controlling the
2
heating elements and measuring temperature. To control the temperature the special software was
3
developed. The Graphical User Interface (GUI) was developed using the MegunoLink (version
4
1.19.18001.101) programming environment (https://www.megunolink.com/). The main window
5
of the developed software showing the controls and temperature variation plot is shown in
6
Supporting Information (Figure S2). The sketch for Arduino is available in the supporting
7
information. The developed software allows variation of heating rate and real time plotting and
8
logging of data. Temperature could be varied from room to ~300 oC. The maximum heating rate
9
3 oC/s.
10
Mass spectrometer. All experiments were performed on a modified QExactive Orbitrap mass
11
spectrometer (Thermo) with installed ion funnel and fore vacuum MALDI (Matrix assisted laser
12
desorption ionization) system (Spectroglyph Company, USA). Pressure in the ion funnel was
13
measured by KJLC® 300 Series Gauge. The pressure could be varied by means of valve. Mass
14
spectra were recorded by Orbitrap with the resolving power 140 000. The front panel with the
15
MALDI translational stage was replaced with specially developed plate made from opaque
16
organic glass using laser cutting system. For the ionization we used vacuum UV lamp
17
(Chromdet-Ecology Company, Russia). This glow discharge lamp is filled with Kr and produces
18
photons with energy 10 and 10.6 eV. No dopants were used. Ions were detected in positive and
19
negative mode.
20
Data analysis. For initial data analysis and determination of molecular formulas, we used
21
Thermo Xcalibur Qual Browser (4.0.27.19) software. After initial spectrum assessment,
22
chromatograms were analyzed using MzMine 2.29 software43. Following parameters were used:
23
noise level = 10, minimum peak height = 10, m/z tolerance: 0.0 m/z or 15 ppm. For formula
ACS Paragon Plus Environment
5
Analytical Chemistry 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 6 of 22
1
prediction we used following constrains: 0
