GC-APCI/IMS-QTOF for the Analysis of Diesel

Sheher Bano MohsinDavid WongRob Ley

Why EPA Regulates Diesel Fuel

The amount of sulfur in diesel fuel is directly linked to the amount of pollution produced when the fuel is burned in an engine. Higher levels of sulfur increase pollutants.

Practical Advances in Petroleum

Processing, Volume 1

edited by Chang Samuel Hsu, Paul Robinson

• Instrumentation – IM-QTOF with GC1. Instrument Overview

2. Benefits of IM

• Results

Things to Cover

•Increases MS flexibility by enabling both GC and LC MS

•Analysis of wider range of compounds

•Proven QTOF LC/MS platform

•Proven 7890 GC performance

G3212A- GC APCI Interface

Page 5

0

IM-QTOF Instrument Overview

6

• System sensitivity optimized using electrodynamic ion funnels to focus and transmit ions

• Ion Mobility resolution optimized while maintaining QTOF performance (mass resolution and accuracy)

• Ion Fragmentation can be selected using standard QTOF collision cell (CID)

• Bandwidth of QTOF data acquisition and processing channel was increased by 10 fold to match the ion mobility data rates

Ion Mobility System Design

7

Ionization source: Ion generation (ESI, AJS, Nano ESI, ChipCube, GC-APCI etc.)

Front ion funnel: Efficient ion collection, desolvation and excess gas removal

Trap funnel: Ion accumulation and introducing ion packets into drift cell

Drift cell: Uniform low field ion mobility allows direct determination of accurate CCS (Ω)

Rear funnel: Efficient ion refocusing and introduction into mass analyzer

Benefits of Adding Ion Mobility to GC/Q-TOF/MS

• Adds Additional Separation Power • A new dimension of separation for increased mass spectral

purity especially for complex mixture analysis

• Improves Detection Limits • Helps to eliminate interference from other analytes and

background in the sample mixture

• Efficient ion focusing and transfer through the ion optics maximizes sensitivity for the overall system

• Enhances Compound Identification

• Improves confidence in compound identification and ion

structure correlation through accurate collision cross section

measurements

8

Excellent in Resolution and Separation Power

9

Chromatography Ion Mobility Mass

~ minutes ~ 60 milli-seconds ~ 100 m seconds

IMS fits between LC and TOF MS on the separation time scale

Adding Ion Mobility Spectrometry

An Additional Dimension of Full Spectral Specificity

Mass Spectrum

Signal Response

Agilent Restricted Page 10

Chromatogram ~ minutes

Drift Spectrum ~ 60 msec

Mass Spectra ~ 100-200 usec

tdrift

Detector

AnalyteIons

GatingOptics

Ion Mobility Cell

t0

VH VL

Electric Field

Stacked ring ion guide gives linear field

Basic Operational Principle of Ion MobilityFor Conventional DC Uniform Field IMS

June 27, 2016 11

𝑣 = 𝐾 𝐸 ∝𝑒 𝐸

𝑃 𝑇 Ω

Resolving Structural Sugar Isomers C18H32O16

June 27, 2016 12

Melezitose

Raffinose

Resolving two isobaric trisaccharides

Conformational Space Occupancy of Biomolecules

Co

llis

ion

Cro

ss S

ecti

on

(Å2)

Mass (Da)

Hypothetical Ordering ofBiomolecular Classes

lipids

carbohydrates

peptides

oligonucleotides

Lipid Analysis

Tetraalkylammonium Salts+2 ions

+3 ions

+1 ions

+4 ions

Ion

Mo

bilit

y D

rift

Tim

e (

ms)

Mass (Da)

0

0

20

40

50

500 1000 1500 2000

10

30

60

70

L-α-phosphotidylethanolamines (PE)

TAA-3

TAA-16

TAA-12

TAA-10

TAA-8TAA-7

TAA-6TAA-5

TAA-4

GC-APCI-IMS of Diesel

C12H8S

C14H12SC13H10S

C15H14S

C16H14S

Extracting the dibenzothiophenes(Mass defect below 0.1 amu)

Diesel B

Diesel C

Kendrick Mass Defect Plot showing series of related compounds with

same Kendrick mass Defect

184 198 212 226 240 254

Dibenzothiophenes in Diesel Sample before HDS

Comparing Diesel B to C

Comparing elution profile in the same retention time window for the treated and untreated samples

Chromatogram of Diesel sample before HDS

Focusing on one area of the map

Kendrick Plot showing Background and 4,6-DBT with their respective different mass defects

Species separated out by different drift times

Sulfur and Desulfurized Compounds

C13H10S

Ring Structures with Sulfur

Drift Spectra

Drift Spectra of a series

C9H8S

Complexity around 149 m/z

Deisel Sample after HDS

Focusing on a small area

Kendrick Mass Defect for a series of related Compounds with KMD of 0.1008

C12H8, C13H10, C14H12, C15H14, C16H16, C17H18 etc

C15H18

C15H16

C15H20C15H22

IMS map for molecular weights from m/z 178 - m/z 232

Addition of methyl group within a C15 series

C15H18C15H20

C15H22

C15H16

C15H14

C15H12

Extracting a thin slice of the chromatogram

Several Possible Structures

4.4 minutes

3.4 minutes

• IM-QTOF with the GC-APCI interface can be used to study HDS

Conclusions• IM-QTOF with the GC-APCI interface can be used to study HDS

Acknowledgements

• Ken Imatani

• David Wong

• Rob Ley