The document discusses the importance of sample preparation in analytical chemistry. It notes that sample preparation takes up the majority of time spent on analytical methods and is a major source of error. The document provides tips for improving sample preparation, including thoroughly understanding the target compounds and matrix, selecting appropriate techniques, using smart calibration strategies, and taking time to evaluate different approaches. It also highlights sorptive extraction techniques as popular methods that simplify sample preparation by eliminating extraction solvents.

1. The
X
TRUTH
about
sample prep_
Jvercamm
www.is-x.be

2. Sample prep plays a vital role in virtually every
analytical procedure_

3. Efficiency & of a measurement method are quality
primarily determined by sample
preparation_

4. Duration sample prep is often tedious and time-
consuming_
Sampling_ 6%
Analysis_ 6%
Data analysis_ 27%
Sample prep_ 61%

5. Error sources sample prep is prime contributor_
Contamination_ 4%
Integration_ 6%
Injection_ 6%
Chromatography_ 7%
Instrument_ 8%
Calibration_ 8%
Columns_ 11%
Operator_ 19%
Sample prep_ 30%

6. What can we
do
about it…?

7. Adagium the best prep is no prep_
What you want is what you get_
(Unfortunately)
• Dilute-and-shoot_
• Generic methods_
• Less selective methods_

8. New hardware to address this issue_
Powerful 'black box mass spectrometers_
• Single quad and ion trap_
• Triple quad_
• Q/TOF, orbitrap_
• TOF/TOF

9. Reality check sample prep remains mandatory
Selective detection does not tackle injection issues_
• GC/MS and inlet contamination_
• LC/MS and ion suppression_

10. Nobody likes sample prep…

11. Solutions are ubiquitous_
Scientific literature, discussion forums and application notes from
manufacturers.
Can you still find your way in this maze…?

12. Recycling is commonplace in analytical chemistry
publications_
Unique and original publications are hard to find in the vast and
continuously growing amount of data.

13. Example ScienceDirect @ Jan 2011_
180.000
x 10
80.000
12.000 10.000

14. Be vigilant…
vig·i·lant
”vij-uh-luh nt”
1. keenly watchful to detect danger; wary
2. ever awake and alert; sleeplessly watchful

15. 1
Know
Classify on,
your target compounds_
• Compound volatility_
• Polarity & reactivity_
• Intended concentration level_

16. Know your target compounds_
Compound volatility,
• Permanent gases_
• Volatile compounds_
• Semi-volatile compounds_
• Non-volatile compounds_

17. Know your target compounds_
Polarity & reactivity,
• Apolar
• Semi-polar
• Polar acidic
• Polar basic

18. Know your target compounds_
Classify on concentration level,
• percentage level_
• parts-per-million level_
• parts-per-billion level_
• parts-per-trillion level, 1 s in 32.000 year_

19. 2
Know
Classify on,
your matrix_
• Similarity to targets_
• Overall complexity_
• MW distribution_

20. Know your matrix_
Unsimilarity is the basis of clean-up,
• Exploit orthogonality_
• Use normal phase_
• Ionisable at different pH_

21. Know your matrix_
Combined complexity & similarity,
• Good chromatography_
• Heart-cut GC_
• Backflush_

22. Know your matrix_
High molecular weight interferences,
• Matrix solid phase dispersion_
• Backflush_
• Gel permeation_

23. 3
Know
Combine information,
your techniques_
• Direct injection_
• Preconcentration_
• Extraction_
• Derivatisation_

24. Know your techniques_
Permanent gases with GC,
• High levels, direct injection_
• Trace levels, air server_
• Complex matrix, chromatography_

25. Know your techniques_
Volatile components with GC,
• High levels, static headspace_
• Trace levels, thermal desorption_
ITEX_
• Complex matrix, multiple headspace_
thermal extraction_
pyrolysis_
• Polar compounds, derivatisation_

26. Know your techniques_
Semi-volatile components with GC,
• High levels, LLE, SPE
• Trace levels, evaporate solvent_
MEPS_
• Complex matrix, clean-up_
• Polar compounds, derivatisation_
• High boilers, on-column injection_

27. Know your techniques_
Non-volatile components with LC,
• GC is possible, derivatisation_
• High levels direct injection_
• Trace levels, SPE_
• Complex matrix, clean-up_
• Polarity, LC mode_

28. 4
Use smart calibration solutions_
Exploit the power of MS,
• Isotope dilution analysis_
• Internal standards prior to prep_
• Surrogates prior to injection_
• Standard addition for complex matrices_

29. 5
Take your time & evaluate_
Developing a sample prep method is often challenging and
quite frustrating. Immediate success is highly uncertain, even for
experienced users..
Take your time and carefully assess all possibilities.

30. But what about sorption…?

31. Definition of sorptive extraction
Family of miniature extraction techniques that use polydimethyl
siloxane or polyacrylate as enrichment phase_

32. Applications of sorptive extraction
Sorptive extractions are particularly popular in scientific literature.
Applications include,
• Headspace extraction_
• Direct extraction_
• In-situ derivatisation_
• Passive sampling_

33. Typical configurations
Several techiques have been introduced,
• solid phase microextraction_
• stir bar sorptive extraction_
• solid phase dynamic extraction_
• single drop microextraction_

34. Advantages of sorptive extraction
Applied configurations are simple to use and eliminate extraction
solvents. After sampling, trapped components are released by
heat, without partial losses (sensitivity)_

35. Some remarks to take into account
Sorptive extraction uses equilibrium extraction,
• Takes some time to complete
• Non-exhaustive extraction
• Equilibrium depends on matrix
Preserve for clean matrices !

36. Comparison fiber versus stir bar
Use a mixed mode SPME fiber to attain sensitivities superior to
SBSE,
• Fully automated_
• In a fraction of time_

37. Concluding remarks

38. Don’t forget these things…
• Nobody likes sample prep_
• Neglecting sample prep is riskful_
• Be vigilante_
• Know your business_
• Take your time_
Good luck !

39. Additional information
Dr. Joeri Vercammen
www.is-x.be
j.vercammen@is-x.be