1. Solid Sample Extraction for Pesticides, PCBs,
PAHs and Dioxin/Furans Analysis using
Accelerated Solvent Extraction (ASE) System
Bhupander Kumar
Scientist
National Reference Trace Organics Laboratory
Central Pollution Control Board
East Arjun Nagar
Delhi-110032
2. Principles of Extraction
Physical and chemical processes influence solid-liquid
extractions
– Diffusion
– Viscosity
– Surface tension
– Solubility
– Binding energy of physio-chemico sorption interactions
3. Principles of Extraction
General improvement of chemical processes as temperature
increases
– Diffusion increases, viscosity decreases, surface
tension decreases, solubility increases, and solute
interactions with matrix are decreased
“Like dissolves like” principle is important
– Polar solvent for polar analytes
Particle size influences extraction rate
5. Comparison of Liquid Extraction Techniques
Techniques Sample Size
(g)
Solvent Vol.
(ml)
Average Extraction
Time* (hours)
Soxhlet 10 – 30 300 – 500 4 – 48
Sonication 30 300 – 400 0.5 – 1
Microwave 5 30 0.5 - 1
Automated Soxhlet 10 50 0.5 – 2
ASE 10 - 100 15 - 120 0.2 – 0.5
*Extraction times are based on a per sample basis. This estimate of
time does not include sample weighing, sample loading, or sample
concentration.
6. What is Accelerated Solvent Extractor
(ASE) ?
ASE is a technique for extracting solid and
semi-solid samples with liquid solvents
ASE Uses elevated temperatures (40- 200oC) and
pressures (1500-2000 psi)
Uses small quantities of solvent and short
periods of time
-15 mL and 15 min for 10 g samples
ASE can be used to replace Soxhlet, Sonication,
Boiling, Wrist Shaker, and other extraction
methods
7. Comparison of extraction for Dioxin and Furans
by ASE and Soxhlet
ASE Soxhlet
Sample size 4 – 10 grams 4 – 10 grams
Solvent Toluene Toluene
Solvent volume (ml) 15 250
Temperature o C 150 - 180 << Boiling point
Pressure 10 MPs Atmospheric
Time 2 x10 min 18 hours
8. Environmental
Matrices*
Soils, Sludges, Sediments
Plant and animal tissues
Air Samples
– Glass filters
– Quartz filters
– Tenax resins
– Charcoal adsorbents
– PUF and XAD resins
Essentially all solid or semi-solid
matrices analyzed for environmental
contaminants
* Pesticides, Herbicides, Semi-volatiles,
PAHs, PCBs ,PCDDs and PCDFs
ASE Application Areas
9. Food
Matrices
Food contaminant analysis
– Pesticides
– Herbicides
– PCBs
– PAHs
– dioxins, etc.
Component analysis
– Lipid content
– Flavors
– aromas, etc.
ASE Application Areas
12. ASE 350
ASE 350 automated extraction system for
solid and semisolid samples
Extraction of 24 sample at a time in various
size of cells (1, 2, 10, 22, 34, 66, and 100 ml)
Collection vessels are 60 and 250 ml size
Three 2L solvents can be hold
Temp. limit 4000 C
Work at pressure of 1500 - 2000 psi
Can use single solvents or gradient of solvent
Typical extraction times of 15 min per sample
Extraction solvent volumes of 40–150 mL
Solvents
Control panel
Collection tray with vessels
Extraction cells
14. Cell Loading
Add filter to cell
Weigh sample
Mix Sample with dispersant
– ASE prep DE or Ottawa sand
Fill empty space with sand or DE
Transfer sample to cell using ASE funnel
Add surrogate or other tracer compounds
Add filter (optional) and Cap cell
Load cell in extraction tray
18. Methods Optimization in ASE
Sample preparation or pretreatment
– Grinding
– Dispersing
– Drying
19. Grinding
Sample with larger particles should be ground
Efficient extraction requires minimum particle size
generally < 0.5 mm
Grinding can be done by mortar and pestle or electric
grinder and mills
20. Dispersing
The aggregation of sample particles prevent efficient extraction
Dispersing with samples that tends to compact in cell outlet
Samples with fine particles can adhere tightly to each other under
high pressure
Dispersing can be achieved by ASE Prep DE (Diatomaceous earth)
or Ottawa sand
Sea sand is not recommended because it contains very small
particles which block system
Run dispersing extraction blank to verify its cleanliness
21. Drying
Wet sample prevent non-polar solvents from reaching the target analyte
Sample drying prior to extraction is the way to handle wet samples
Drying is normally done by adding ASE Prep DE
Cellulose may be used for very wet samples like fruits and vegetables
Magnesium sulfate is not recommended due to its melting at high temp.
Sodium sulfate is also not recommended because it could solubilize and
can deposited in exit line
Following ratios have been applied to various samples
Sample that appear dry: 4 g sample to 1 g DE
Sample that appear wet: 4 g sample to 2 g DE
22. Examples of Sample Preparation
Sample Type Sample preparation
Wet soil/sediment 10 g sample with 5 g
of ASE Prep DE or Ottawa sand
Fish tissue (80 % moisture) 3 g sample with 2 g
of ASE Prep DE or Ottawa sand
Fruit / vegetables 10 g sample with 5 g
of ASE Prep DE or Ottawa sand
or 2 g cellulose
Creams/lotions 2 g sample with 3 g
of ASE Prep DE or Ottawa sand
Ground polymer 1 – 3 g sample with 1 – 3 g
of ASE Prep DE or Ottawa sand
23. ASE Extraction Parameters
Solvent
Pressure
Temperature
Static Time
Flush Volume
Purge Time
Cycles
24. Solvents
Solvent must be able to solubilize the target analytes while
leaving the sample matrix intact
For efficient extraction “Like dissolves like” principle is
important
Solvent mixture of different polarities can be used to extract
broad range of compounds
Solvents with aqueous buffers can be used in ASE
Strong acids (HCl, HNO3,H2SO4) are not recommended, due to
their ability to react with the stainless steel in the system
25. Temperature
Start at 100ºC or 20ºC below the analyte/matrix degradation point
Run multiple extractions on same sample at 100º C
Increase temperature to improve recoveries
Be aware of thermal limitations of sample and analytes
1000 C is better for pesticides, herbicides, PCBs and PAHs
1500 C is better for Dioxin/furans
26. Pressure
Start at 1500 -2000 psi
Consider lower pressures for samples likely to compress
For most samples pressure has no noticeable effect
Maximum pressure is 2000 psi
ASE 200, 300 and 350 are set at 1500 psi
27. Extraction Time
Increased extraction time
– Allows longer time for analyte diffusion
Improved recovery obtained with some samples
Increased number of static cycles gives better results
28. Static Time Cycles
Static extraction cycles
– Better to have multiple cycles than one long cycle
» Two 5-min cycles are good than one 10-min
cycle
» Five 2-min cycles even better
29. Flush Volume
Solvent volume goes into cell
Set at 60% of cell volume
When used with multiple static cycle, flush volume per
cycle is the total % divided by the number of cycles
1 cycle with 60% flush volume
2 cycle with 30%
3 cycle with 20%
30. Purge Time
Purpose is to get solvent out of cell; no impact on
recovery of analytes
Set purge time for 30-45 seconds per 11 mL of cell
volume (90-135 sec for 33-mL cell)
Increase purge time for densely packed samples
Increase purge time for non-volatile solvents
Increase purge time for larger cells: 66-mL or 100-mL
cells
31. Achieve Selectivity
Solvent choice
– Adjust polarity
Selective sorbents
– Alumina for fat retention
Temperature
– Higher temperature = more co-extractables
Combinations of the above
32. Check ASE Extraction Parameters
If recoveries are low:
1) Increase the temperature
2) Add static cycles
3) Increase the static time
4) Select a different solvent
Diagnostic skill
– Rinse test
– Run three blanks: check weight of solvent collected
– RSD: 3% or less
33. ASE Parameters for
PCDDs/Fs and PCBs
Conditions PCDDs/Fs PCBs
Matrix Soil, sludge,
sed. Etc (10 g)
PUF Fish tissue
(10 g)
Sediment
(10 g)
Solvent Toluene Hexane Hexane Acetone/hexane
(1:1)
Temp. 1500C 1000C 1250C 1500C
Pressure 2000 psi 1500 psi 1500 psi 1500 psi
Heatup time 5 min 5 min 6 min 7 min
Static time 10 min 5 min 5 min 7 min
Flush volume 60 % 60 % 60 % 60 %
Purge time 125s 100s 100s 180s
No. of static
cycles
3 1 2 3
34. ASE Parameters for
Herbicides, Pesticides, and PAHs
Conditions Herbicides Pesticides PAHs
Matrix Soil, sludge, sed.
(10 g)
Soil, sludge, sed.
(10 g)
Soil, sludge, sed.
(7 g)
Solvent DCM/acetone
(1:2)
hexane/acetone
(1:1)
DCM/acetone (1:1)
Temp. 1000C 1000C 1000C
Pressure 2000 psi 1500 psi 1500 psi
Heat up time 5 min 5 min 5 min
Static time 5 min 5 min 5 min
Flush volume 60 % 60 % 60 %
Purge time 60s 60s 60 s
No. of static cycles 3 3 3
35. ASE Parameters for
POPs (pesticides, HCB, PCBs, PCDDs/Fs) with
Hexane, DCM, Acetone, Toluene
Conditions Pesticides &
PCBs
HCB PCDDs/Fs
Matrix Soil, sludge. Sediments, Dust, biological
Solvent Hexane/acetone
(1:1)
DCM/acetone
(1:1)
Toluene
Temp. 1000 C 1000 C 1500 C
Pressure 1500 psi 1500 psi 1500 psi
Heat up time 5 min 5 min 7 min
Static time 5 min 5 min 10 min
Flush volume 60 % 60 % 70 %
Purge time 100 s 100 s 120 s
No. of static cycles 2 2 3
36. ASE Parameters for
XAD - 2 (AMBERLITE) Resin
Conditions Cleaning Elution
Solvent Acetone (100%) - one extraction
Hexane/acetone (25:75) – one extraction
Hexane/acetone (50:50) – 3 extraction
Hexane/acetone (50:50)
Temp. 750C 750C
Pressure 1000 psi 1000 psi
Heat up time 5 min 5 min
Static time 5 min 5 min
Flush volume 150 % 150 %
Purge time 120 s 120 s
No. of static
cycles
5 3
37. Thank you for your attention!
bhupander_kumar@yahoo.com
42102378, 9212135238
GO WITH ASE TO SAVE TIME, ENERGY AND
ENVIRONMENT WITH ADEQUATE ACCURACY……!!
