This webinar will provide pesticides residue analysts with valuable information on the development and optimization of gas chromatographic separations and mass spectrometry methods for the analysis of pesticide residues in food. The expert speakers will share their knowledge in understanding the critical points of the method, assisting analysts in modifying existing methods, and understanding instrumental and software technologies with the goal of improving laboratory productivity and reducing the overall cost per sample. The results of experiments for both screening and quantification workflows, using the latest technology, will be presented.
Call Us ≽ 9953322196 ≼ Call Girls In Mukherjee Nagar(Delhi) |
Chromatography: Pesticide Residue Analysis Webinar Series: Part 3 of 4: Maximizing Analysis Efficiency through GC-MS Approaches
1. Maximizing Efficiency in Analysis through New
GC-MS Approaches
Richard Fussell
Vertical Marketing Manager, Food and Beverage,
Thermo Fisher Scientific, Hemel Hempstead, UK
Dominic Roberts
Senior Applications Scientist, GC-MS,
Thermo Fisher Scientific, Runcorn, UK
PO71686-EN 0615S
2. 2
Overview
• The analytical challenge
• User requirements for GC-MS/MS analysis of pesticides
• Critical aspects of the method & improving efficiency
• Injector
• Column configuration
• Instrumental parameters
• Latest GC-MS/MS developments including
GC-Orbitrap for pesticide screening
• Summary
3. 3
Typical Pesticides Workflow
Register for future webinars and to view recordings of past webinars at
www.chromatographyonline.com/LCGCwebseminars
1. Sample Prep: March 24th 2. LC-MS Analysis: April 29th
3. GC-MS Analysis: June 17th 4. Data Processing/Analysis: July 15th
5. 5
Pesticide Analysis: GC-MS
• Many compounds not amenable to LC separation
• Low polarity–poor atmospheric pressure ionization
• GC offers good separation efficiency
• Choice of detectors
• Easy coupling with MS for increased
selectivity
• EI/CI spectra for identification of analytes
7. 7
Selectivity: Selected Ion Monitoring (SIM) and SRM
DDE-p,p’, 0.05 mg/kg in green tea, 1.0 uL splitless injection
8. 8
Selectivity: SIM and SRM
DDE-p,p’, 0.001 mg/kg in green tea, 1.0 uL splitless injection
9. 9
The world leader in serving science
Proprietary & Confidential
Key Factors in the GC-MS/MS Method
10. 10
Hot split/
splitless
Programmed
Temperature
PTV
Typical GC Injector Choices for pesticides
• Liquid introduction by syringe
“GC Injection is the Achilles
Heel in GC”
Bertsch 1983, Univ. Alabama
• Most commonly used technique
• Split/Splitless injection (SSL)
• Programmed temperature (PTV)
11. 11
GC Inlets
• Splitless
• maximum sensitivity
• excellent repeatability for low volumes
• simple, probably most wide used
• Split
• reproducible
• less discrimination (short residence time)
• Shoot and Dilute
• Programmed Temperature Vaporising (PTV) injector
• versatile and excellent performance if optimised
• reduced discrimination
• many liner types (baffled, dimpled, packed, etc)
• packed liners (possible discrimination)
• large volume injection (solvent removal/exchange in liner)
• Cool on-column (not widely used)
12. 12
GC Liner Selection for Pesticides
• In pesticide analyisis QuEChERS extractions are typical and result in
extractions in acetonitrile.
• Many labs use acetonitrile as GC injection solvent
• Requires careful method optimisation
• Considerations in liner selection for acetonitrile injections are:
• Internal diameter
• Type of injection
• Packing of liner
• Other liner features ie baffles....
13. 13
GC liners – Type of Injection
• Split
• Typically open ended at the bottom
• Enables split flow to pass across the bottom of the liner removing a portion of the
sample, allowing a split injection to be performed
• Splitless
• Typically tapered at the bottom with the column inserted into the taper
• Funnels sample onto the column and minimizes sample contact with reactive metal
components
• PTV
• Generally used with very active compounds such as pesticides
• Good option for acetonitrile injection solvents
• Thermally liable compounds protected
14. 14
PTV Injector: Key Points
• Minimal thermal mass for
fast cooling and heating
• Injection volumes from nano liter
up to largevolume
• Cold injection technique
• Clean step possibility for
keeping the liner inert
• Multiple injection modes
OVEN
column
Liner
Cooling by fan Heater element
Inlet Carrier
Septum Purge
Split line
Slide courtesy of Thermo Fisher Scientific
15. 15
System Contamination with Heavy Matrices
9.03 min (start of run)
1.0 µg/ml dimethoate in
crude extracts of lettuce
- 3 µl splitless
9.06 (Injection ~20)
GC Liner
Slide courtesy of Fera, UK
19. 19
Guard columns
• Analytical columns with a length of 5-10 m of deactivated fused silica.
They can be purchased already integrated or joined by a union.
• Provides the benefit of protecting the analytical column from
contamination of non-volatile residues. Very important when working
with dirty sample extracts eg. QuEChERS.
• Can also act as a retention gap to improve analyte focussing.
• Maintain retention time of analytes and SRM segments in the method.
• Can be a source of leaks if using a connection.
• Added maintenance
21. 21
Increasing Laboratory Productivity
• Decrease analysis time by shortening the GC run times.
• More samples in less time.
• Increase the number of pesticides in a run.
• More SRMs to accommodate within an analytical run.
• Improve selectivity for various matrices.
• Increased number of SRMs per compound.
• See beyond the targets.
• Full Scan and SRM data acquisition in the same experiment.
Expect More
Performance
22. 22
Fast GC-MS Pesticide Residue Analysis
Challenges:
• Complexity of elution when using
fast GC
• Large number of compounds
(SRMs) in short time
• Many SRM transitions can result
in sensitivity loss
Solution:
• High speed analyzer
• Fast collision cell
• Short SRM dwell times with very
short inter-scan delays
23. 23
TSQ 8000 Evo GC-MS/MS
Expect More
Capacity
• Analytical instrumentation:
Thermo Scientific™ TSQ ™ 8000 Evo GC-MS/MS
Thermo Scientific™ TRACE™ 1310 GC
Thermo Scientific™ TriPlus RSH™ autosampler (liquid injection set-up)
• EvoCell
• Rapid, innovative collision cell technology
• Increased method capacity
• More compounds
• More SRM transitions
• Up to 4x more transitions whilst maintaining
method sensitivity low analyte concentrations
24. 24
Increasing Laboratory Productivity
• Decrease the analysis time by shortening the GC run times.
• More samples in less time.
• More SRM Increase the number of pesticides in a run.
• s to accommodate within an analytical run.
• Improved selectivity for various matrices
• Increase the number of SRMs per compound.
• Seeing beyond the targets
• Full Scan and SRM data acquisition in the same experiment.
27. 27
Pesticide MRM Database
The problem:
• Growing list of target compounds require
continuous adjustment to an existing SRM
database.
• Some SRM transitions are not suitable for all
matrices. Addition of new SRM transitions can be
time consuming.
The solution:
• Automated SRM development with AutoSRM.
28. 28
AutoSRM: Fast, Simple Route to Optimized SRM
1) Precursor ion selection
2) Product ion
selection
3) Collision energy
optimization
AutoSRM automates
the development of
SRM methodology
29. 29
Highlights of AutoSRM
• Automates the following:
• Creation of full scan, product ion scan, and SRM methods
• Creation of sample sequences
• Creation of data layouts for analyzing results
• Selection of precursor, product, and collision energies
End result showing optimized transition
30. 30
Timed-SRM: Using Dwell Times Efficiently
Classical segmented SRM
TSQ 8000 EVO timed SRM
Classical segmented SRM:
• Complex to set up
• Wasted dwell time
• Reduced sensitivity
• Reduced tolerance to RT shifts
TSQ 8000 Evo timed-SRM:
• Automated set-up
• Full optimized dwell time
• Optimal sensitivity
• Increased resistance to RT shifts
31. 31
Increase Laboratory Productivity
• Decrease the analysis time by shortening the GC run times.
• More samples in less time.
• Increase the number of pesticides in a run.
• More SRMs to accommodate within an analytical run.
• Improved selectivity for various matrices
• Increase the number of SRMs per compound.
• Seeing beyond the targets
• Full Scan and SRM data acquisition in the same experiment.
36. 36
Thermo Scientific TSQ 8000 EVO
Pesticide Analyzer
A complete pesticide method
implementation, management
and maintenance solution to
drive unstoppable result
productivity
TSQ 8000 EVO PA designed to
create powerful pesticide
methods that are:
1. Self-customized
2. Auto-optimized
Pesticide Analyzer
37. 37
Powering the TSQ 8000 Pesticide Analyzer
• Preconfigured performance leading TSQ
8000 EVO GC-MS/MS system featuring the
award winning TRACE1310 GC
• Pre-loaded acquisition methods
• Thermo Scientific TraceGOLD GC Column
and consumable technology
• Tracefinder 3.2 EFS Data Processing
software
• 600+ Pesticide compound database (CDB)
with 1500 + SRM transitions
• AutoSRM & timed SRM (t-SRM)
• Pesticide Analyzer installation guide
39. 39
Q Exactive GC for Pesticide Analysis
• Launched at ASMS June 2015.
• Screen (qualitative and quantitative) samples for pesticides within a single
analysis, fast and at a competitive cost.
• To increase the scope of the analysis, by using high resolution full scan mass
spectrometry.
• Untargeted analysis where a generic full scan acquisition is run, followed by
targeted data processing of a list of compounds.
• Retrospective data analysis is possible to identify new compounds that were not
screened for at the time of acquisition.
41. 41
An Example Study
• To evaluate the performance of Thermo Scientific Q Exactive GC hybrid
quadrupole-Orbitrap mass spectrometer for the reliable screening of
GC amenable pesticides.
• To screen for a wide range of pesticides in different sample matrices
with the highest level of confidence possible.
• To determine if a pesticide is present in a sample above the MRL which
is typically 10 ng/g (ppb).
42. 42
Experimental
• Sample introduction was performed using a Thermo Scientific™ TriPlus™ RSH
autosampler, and chromatographic separation was obtained with a Thermo Scientific™
TRACE™ 1310 GC. Thermo Scientific™ TraceGOLD TG-5SilMS 15 m x 0.25 mm I.D. x
0.25 µm film capillary column.
• Q Exactive GC hybrid quadrupole-orbitrap mass spectrometer was used. The system was
operated in EI using full scan and 15k, 30k, 60K and 120k resolution (FWHM, m/z 200).
Data was acquired with a minimum of 10 points/peak.
• Data was acquired and processed using the TraceFinder version 3.3 software.
44. 44
Screening Criteria Used for Positive Identification
Iden%fica%on
Point
Tolerance
Primary
ID
Confirmatory
ID
Reten%on
%me
20
seconds
Accurate
Mass
2
ppm
Fragment
ions
2
ppm
Isotopic
pa8ern
>70%
NIST
Library
match
>600
Ion
ra%o
30%
48. 48
D:Dom Data...21jan_038 01/22/15 03:37:38
21jan_026 #3957 RT: 5.78 AV: 1 NL: 6.28E6
T: FTMS + p EI Full ms [50.00-500.00]
127.008 127.010 127.012 127.014 127.016 127.018 127.020 127.022 127.024 127.026 127.028 127.030 127.032 127.034
m/z
0
20
40
60
80
100
RelativeAbundance
127.02067
21jan_030 #2240 RT: 5.78 AV: 1 NL: 2.39E6
T: FTMS + p EI Full ms [50.00-500.00]
127.008 127.010 127.012 127.014 127.016 127.018 127.020 127.022 127.024 127.026 127.028 127.030 127.032 127.034
m/z
0
20
40
60
80
100
RelativeAbundance
127.02164
127.01821
21jan_034 #1192 RT: 5.79 AV: 1 NL: 3.61E6
T: FTMS + p EI Full lock ms [50.00-500.00]
127.008 127.010 127.012 127.014 127.016 127.018 127.020 127.022 127.024 127.026 127.028 127.030 127.032 127.034
m/z
0
20
40
60
80
100
RelativeAbundance
127.02117127.01826
21jan_038 #623 RT: 5.79 AV: 1 NL: 5.49E6
T: FTMS + p EI Full lock ms [50.00-500.00]
127.008 127.010 127.012 127.014 127.016 127.018 127.020 127.022 127.024 127.026 127.028 127.030 127.032 127.034
m/z
0
20
40
60
80
100
RelativeAbundance
127.01833
127.02118
127.02261
30K
60K
120K
Chlorpropham
Matrix
Mass
difference
=
18.4
ppm
Mass
difference
=
0.9
ppm
Mass
difference
=
0.5
ppm
15K
Mass
difference
=
0
ppm
Effect of Resolving Power on Mass Accuracy
Chlorpropham in Leek (10 ng/g)
49. 49
Scan Speed and Accurate Mass Across Peaks 60K
• XIC
of
diazinon(m/z
179.11789
±5
ppm
mass
window)
in
wheat
at
10
ng/g
showing
~11
scans/peak
(peak
width
1.8
sec).
Average = 0.33 ppm
RMS
51. 51
Linearity
• XIC (quan and confirm ions) and calibration curve for Fenpropimorph in leek.
• Triplicate injections of the calibration series was performed with good linearity
across (0.5 – 50 ng/g).
• No internal standard correction.
R2 = 0.9999
52. 52
Conclusions
• Careful method optimisation focussing on the injection parameters.
• Routine pesticides analysis with the EVO offers sensitivity, high analysis
speed and easy database management at low cost
• Using the available dwell time wisely:
• Timed-SRM ensures minimal loss of time spent to acquire data.
• Q Exactive GC system improves efficiency by increasing the scope of the
analysis:
• Full scan non-targeted acquisition.
• Provides the required sensitivity and selectivity in complex matrices for routine
pesticide screening and quantification.
• Enables the detection and identification of unknown compounds.
Efficient and robust pesticide analysis can be achieved by:
53. 53
Thermo Scientific Food and Environmental
Communities: Resources
• View application notes, on-demand webinars, product information, and
many more resources on our Pesticides and Food Communities Libraries:
www.thermoscientific.com/pesticides www.thermoscientific.com/foodandbeverage
54. 54
Thank You for Listening
Questions?
Stay connected with us
Twitter
@ChromSolutions
Analyte Guru Blog
http://www.analyteguru.com
YouTube
http://www.youtube.com/ChromSolutions
Facebook
http://www.facebook.com/
ChromatographySolutions
Pinterest
http://pinterest.com/chromsolutions/