Details
Original language | English |
---|---|
Pages (from-to) | 3610-3621 |
Number of pages | 12 |
Journal | ANALYST |
Volume | 148 |
Issue number | 15 |
Publication status | Published - 5 Jul 2023 |
Abstract
As ion mobility spectrometry (IMS) is used with mass spectrometry in more applications, increased emphasis is placed on the ion-neutral collisional cross sections (CCS) to identify unknown analytes in complex matrices. While CCS values can provide useful information about relative analyte size, several critical assumptions are inherent in the most common method of calculating CCS values, the Mason-Schamp equation. The largest source of error in the Mason-Schamp equation originates from not accounting for higher reduced electric field strengths, which are present in low-pressure instruments that require calibration. Previous corrections based on field strength have been proposed in literature, but their data used atomic ions in atomic gases, whereas most applications examine molecules measured in nitrogen. Here, we use a series of halogenated anilines measured in air and nitrogen between 6-120 Td on a first principles ion mobility instrument (HiKE-IMS). With this series of measurements, the average velocity of the ion packet is known allowing for direct calculation of reduced mobilities (K0), alpha functions, and finally, a detailed examination of CCS as a function of E/N. In the worst-case scenario, there is over a 55% difference in CCS values for molecular ions measured at high fields depending on the method used. When comparing CCS values to those in a database for unknown identification, this difference can lead to misidentification. To immediately alleviate some of the error in calibration procedures, we propose an alternative method using K0 and alpha functions that simulate first principles mobilities at higher fields.
ASJC Scopus subject areas
- Chemistry(all)
- Analytical Chemistry
- Biochemistry, Genetics and Molecular Biology(all)
- Biochemistry
- Environmental Science(all)
- Environmental Chemistry
- Chemistry(all)
- Spectroscopy
- Chemistry(all)
- Electrochemistry
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In: ANALYST, Vol. 148, No. 15, 05.07.2023, p. 3610-3621.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - The dependence of reduced mobility, ion-neutral collisional cross sections, and alpha values on reduced electric field strengths in ion mobility
AU - Naylor, Cameron N.
AU - Schaefer, Christoph
AU - Zimmermann, Stefan
N1 - Funding Information: Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – 318063177 and 390583968.
PY - 2023/7/5
Y1 - 2023/7/5
N2 - As ion mobility spectrometry (IMS) is used with mass spectrometry in more applications, increased emphasis is placed on the ion-neutral collisional cross sections (CCS) to identify unknown analytes in complex matrices. While CCS values can provide useful information about relative analyte size, several critical assumptions are inherent in the most common method of calculating CCS values, the Mason-Schamp equation. The largest source of error in the Mason-Schamp equation originates from not accounting for higher reduced electric field strengths, which are present in low-pressure instruments that require calibration. Previous corrections based on field strength have been proposed in literature, but their data used atomic ions in atomic gases, whereas most applications examine molecules measured in nitrogen. Here, we use a series of halogenated anilines measured in air and nitrogen between 6-120 Td on a first principles ion mobility instrument (HiKE-IMS). With this series of measurements, the average velocity of the ion packet is known allowing for direct calculation of reduced mobilities (K0), alpha functions, and finally, a detailed examination of CCS as a function of E/N. In the worst-case scenario, there is over a 55% difference in CCS values for molecular ions measured at high fields depending on the method used. When comparing CCS values to those in a database for unknown identification, this difference can lead to misidentification. To immediately alleviate some of the error in calibration procedures, we propose an alternative method using K0 and alpha functions that simulate first principles mobilities at higher fields.
AB - As ion mobility spectrometry (IMS) is used with mass spectrometry in more applications, increased emphasis is placed on the ion-neutral collisional cross sections (CCS) to identify unknown analytes in complex matrices. While CCS values can provide useful information about relative analyte size, several critical assumptions are inherent in the most common method of calculating CCS values, the Mason-Schamp equation. The largest source of error in the Mason-Schamp equation originates from not accounting for higher reduced electric field strengths, which are present in low-pressure instruments that require calibration. Previous corrections based on field strength have been proposed in literature, but their data used atomic ions in atomic gases, whereas most applications examine molecules measured in nitrogen. Here, we use a series of halogenated anilines measured in air and nitrogen between 6-120 Td on a first principles ion mobility instrument (HiKE-IMS). With this series of measurements, the average velocity of the ion packet is known allowing for direct calculation of reduced mobilities (K0), alpha functions, and finally, a detailed examination of CCS as a function of E/N. In the worst-case scenario, there is over a 55% difference in CCS values for molecular ions measured at high fields depending on the method used. When comparing CCS values to those in a database for unknown identification, this difference can lead to misidentification. To immediately alleviate some of the error in calibration procedures, we propose an alternative method using K0 and alpha functions that simulate first principles mobilities at higher fields.
UR - http://www.scopus.com/inward/record.url?scp=85165255507&partnerID=8YFLogxK
U2 - 10.1039/d3an00493g
DO - 10.1039/d3an00493g
M3 - Article
C2 - 37404048
AN - SCOPUS:85165255507
VL - 148
SP - 3610
EP - 3621
JO - ANALYST
JF - ANALYST
SN - 0003-2654
IS - 15
ER -