Ultrasonic Extraction
Method 3550B
Description:
This SOP describes preparation methods that ensure proper extraction of organic compounds from solids, sludges, and other wastes prior to analysis by GC or GC/MS by SOP #6600, 6700.
Precautions:
Compressed gases (see procedure 0040)
Corrosives (see procedure 0020)
General Requirements (see procedure 0010)
Solvents (see procedure 0030)
Sample Preservation:
Samples to be analyzed for Semivolatiles must be collected in a glass container with a Teflon-lined cap, and refrigerated to 4oC until extraction. Samples may be held for 7 days under refrigeration prior to organic extraction and 40 days prior to analysis.
Interferences:
Interferences can exist as a result of poor extraction techniques, contaminated reagents and instrumentation cleanliness. All glassware associated with the extraction and concentration processes must be thoroughly cleaned prior to use. Caution must be taken to avoid any plastic sample or reagent containers to avoid possible phthalate contamination. A rigorous preventative maintenance routine is mandatory to maintain instrument performance.
Apparatus:
-600mL beakers
-Kuderna-Danish (K-D) apparatus and accessories for concentrating
-Concentrator tube with ground glass joint & spring attachment
-3 Ball Snyder column with ground glass joint
-Connectors for attaching flasks and concentrator tubes
-Vials- crimp top
-1mL syringe
-Funnels with stems
-Glass pasteur pipettes & bulbs
-Concentration Tube
-Activated Carbon Filter
Reagents:
-Methylene Chloride (MeCl2), ACS Grade
-Hexane, ACS Grade
-Sodium Sulfate
-Compressed Nitrogen
-BNA Surrogate Standard- surrogate obtained from purchased stock at 200 and
100pp. Expiration date posted by manufacturer, spike 100mL / sample.
-BNA Matrix Spike Standard- prepare matrix spike from purchased stock
solution. Spike 100mL / sample. (see Table II for a list of spike
compounds)
-Pesticide/PCB Surrogate Standard (DBC/TCMX)- purchased stock, spike 25mL /
sample.
-Pesticide Matrix Spike Solution- purchased stock of standard in spikes 25mL /
sample.
-PCB Spike Standard (Arochlor 1260-1060)- purchased stock of standard in
spikes 25mL / sample.
-PAH and DRO Surrogates- purchased stock of standard in spikes 50mL / sample.
Batching:
A batch is defined as a group of no more than 20 samples of a similar matrix that are processed in any given working period. Each batch requires a method blank; laboratory control sample and a matrix spike/matrix duplicate to be processed with it. Any variations from these guidelines should be noted in the extraction logbook. If there should be more than 20 samples to be extracted, a second set of method blank, laboratory control sample and matrix spike/matrix spike duplicate pair should be analyzed. Throughout the batch extraction procedure, care should be taken that all samples and quality control samples are processed with the same reagents and solvents.
Procedure:
1.0 The sample volume selected will depend on matrix and expected analyte concentration, however, a general guideline is 30g of sample used for sludges and “clean solids” and 2-10g of sample is used for low level waste depending upon the homogeneity of the sample.
2.0 Extraction:
2.1 Homogenize and weigh sample into 600mL labeled beaker.
2.1.1 Place the beaker into the 105oC oven to drive off water. Cool.
2.1.2 Add activated Sodium Sulfate and mix until the consistency of wet sand is achieved.
2.2 Add 200mL of MeCl2 (40mL for low level) and 100mL of the appropriate surrogate, also add 100mL of matrix spike as needed.
2.3 Place beaker in sonicator under horn.
2.3.1 The proper depth for the horn to be immersed in the solvent is just below the line on the horn but not contacting the solid material. Sonication should be done with the controls set on 60% Duty Cycle, Output Control 6, and Time on 6min. Sonicate.
3.0 Concentration:
3.1 Assemble a K-D apparatus. Label with sample info. In a stemmed glass funnel, push glass wool (enough to plug it) into the stem. Fill halfway with sodium sulfate and place so that stem is in the top of the K-D apparatus. Filter sample through the funnel. Rinse sodium sulfate with fresh MeCl2 to make sure that all sample gets through. Add a small boiling chip. Attach Snyder column. For PCB’s and Pest go to section 3.3.1.
3.2 Place assembled apparatus into steam bath. Check for proper boiling such that the macro Snyder column chatters but does not flood.
3.2.1 Boiling chip should remain at the base of the receiving vessel (bottom part). It should not float to the top of the vessel or into the flask. Since MeCl2 boils rather violently, the boiling chip is necessary to ensure smoother evaporation of the solvent. If the sample is concentrating properly, the Snyder column will “chatter” constantly. If the column makes occasional loud or irregular noise, remove the apparatus from the heat, and let cool; add a new boiling chip and return to the heat.
3.2.2 Any sample or quality control extract that has been reduced to dryness needs to be flagged in case some of the target analytes have been boiled out. A notation needs to be made in the extraction logbook under the comments section for the extract. The extract’s vial should also be capped with a different color cap to alert the analyst that the sample had been cooked to dryness and that the data is suspect.
3.3 Once the sample is reduced to approximately 1.0mL, remove from heat. Cool about 10 minutes. For PCB’s and Pest, go to Section 3.3.1 for BNA’s, DRO’s, and PAH’s, go to Section 3.2.1.
3.3.1 For PCB’s and Pest’s, a solvent exchange is necessary. After adding the boiling chip, add 5.0mL of Hexane to the K-D apparatus. Attach the Snyder column and concentrate as in Section 3.2.1. Once the sample is reduced to approximately 5.0mL, remove from the heat and cool.
3.3.2 For BNA’s and PAH’s, transfer the MeCl2 to a concentration tube. Rinse the receiving flask with 5mL fresh MeCl2 and add to the concentration tube.
3.3.2.1 Place concentration tube(s) in metal rack and submerge the bottom half of tube.
3.3.2.2 Place the nitrogen outlet in the upper tenth of the tube and initiate a gentle nitrogen stream. Note: as the volume of MeCl2 begins to drop, it is necessary to rinse the walls of the tube with fresh MeCl2.
3.3.2.3 Stop the nitrogen flow when the solvent volume drops just below 1.0mL. Remove the tube from the water bath. Bring to 10mL volume with new MeCl2.
3.4 Label a vial with the sample ID. Transfer the sample with a glass pipette and close the cap tightly.
3.5 Store the extract in the refrigerator until it is ready for analysis.
4.0 Glassware Cleanup:
4.1 All glassware is to be cleaned first by rinsing with a small amount of MeCl2 (put this waste into a separate container, DO NOT put it down the sink). Then wash with HOT water and very dilute soap, rinse with dilute HCL and ultra-pure water. Place all glassware (except graduated cylinders and separatory funnels) into the oven to dry for about 30 minutes.
4.1.1 If glassware is oily, rinse with MeCl2 until it comes clean.
4.1.2 Make sure to use the small brush to clean the receiving vessels.
4.2 Remember, all glassware is to be clean, cool, and dry before its next use.
4.3 It is best to clean glassware immediately after use.
Quality Control:
§ Each analytical batch extracted for semivolatiles must be accompanied by a blank consisting of ultra-pure water taken trough all extraction steps.
§ Based on notebook order, every 20th analytical sample analyzed must be a QC standard for the analytical parameters analyzed.
§ All weights, volumes, comments, etc. for each batch must be entered in notebook form for data review.
§ As determined by notebook order, every 10th sample of similar matrix shall be analyzed in duplicate; every 20th sample shall be analyzed as a duplicate spike.
§ Failure to meet quality control acceptable limits requires corrective action (see attachment 0150)
Helpful Hints:
§ Turn on steam bath when you are ready to start extractions. It should stay on “med” during concentration, but you do not want it to boil too vigorously. It takes about an hour to heat up on High. ALWAYS check the water level before, during, and after concentration to maintain the proper level. Use ultra-pure water to replenish it.
§ Tighten stopcocks before pouring in the sample, and loosen stopcocks before you leave for the day.
§ There is a dedicated syringe for BNA surrogates --- make sure that you use the right one. Always measure out the BNA surrogates when it is at room temp. Too hot or too cold will affect the concentration. DO NOT use the eppendorf automatic pipettor!!
§ Cover all extracts with foil, not lids. DO NOT use Para film!!
§ DO NOT use anything plastic!! The components of plastic are extracted by MeCl2 and will show up as contamination.
§ If an EMULSION forms:
§ Try to swirl it loose.
§ Add all additions of MeCl2 (for that pH range) and shake. That may break it up.
§ Pour into centrifuge tubes. Sometimes the act of putting it into a smaller container helps.
§ If all else fails, centrifuge. If it does not break, try to centrifuge again for 10 minutes. Use glass pipettes to remove solvent and filter. If you do not get 50% or better of “clear” MeCl2 after this, you have to start all over again with less sample volume or mass.
Reference:
SW846 Method 3550B, 1 to 13
Revision 2; December 1996.
4
Procedure 6020
Revised 05/07