METHOD 3650A ACID-BASE PARTITION CLEANUP. 1.1 Method 3650 was formerly Method 3530 in the second edition of this manual.

Transcription

1 1.0 SCOPE AND APPLICATION METHOD 3650A ACID-BASE PARTITION CLEANUP 1.1 Methd 3650 was frmerly Methd 3530 in the secnd editin f this manual. 1.2 Methd 3650 is a liquid-liquid partitining cleanup methd t separate acid analytes, e.g. rganic acids and phenls, frm base/neutral analytes, e.g. amines, armatic hydrcarbns, and halgenated rganic cmpunds, using ph adjustment. It may be used fr cleanup f petrleum waste prir t analysis r further cleanup (e.g., alumina cleanup). The fllwing cmpunds can be separated by this methd: a Cmpund Name CAS N. Fractin Benz(a)anthracene Base-neutral Benz(a)pyrene Base-neutral Benz(b)fluranthene Base-neutral Chlrdane Base-neutral Chlrinated dibenzdixins Base-neutral 2-Chlrphenl Acid Chrysene Base-neutral Creste Base-neutral and Acid Cresl(s) Acid Dichlrbenzene(s) Base-neutral Dichlrphenxyacetic acid Acid 2,4-Dimethylphenl Acid Dinitrbenzene Base-neutral 4,6-Dinitr--cresl Acid 2,4-Dinitrtluene Base-neutral Heptachlr Base-neutral Hexachlrbenzene Base-neutral Hexachlrbutadiene Base-neutral Hexachlrethane Base-neutral Hexachlrcyclpentadiene Base-neutral Naphthalene Base-neutral Nitrbenzene Base-neutral 4-Nitrphenl Acid Pentachlrphenl Acid Phenl Acid Phrate Base-neutral 2-Picline Base-neutral Pyridine Base-neutral Tetrachlrbenzene(s) Base-neutral Tetrachlrphenl(s) Acid Txaphene Base-neutral Trichlrphenl(s) Acid 2,4,5-TP (Silvex) Acid a Chemical Abstract Services Registry Number. CD-ROM 3650A - 1 Revisin 1

2 2.0 SUMMARY OF METHOD 2.1 The slvent extract frm a prir slvent extractin methd is shaken with water that is strngly basic. The acid analytes partitin int the aqueus layer, whereas, the basic and neutral cmpunds stay in the rganic slvent. The base/neutral fractin is cncentrated and is then ready fr further cleanup, if necessary, r analysis. The aqueus layer is acidified and extracted with an rganic slvent. This extract is cncentrated (if necessary) and is then ready fr analysis f the acid analytes. 3.0 INTERFERENCES 3.1 Mre extensive prcedures than thse utlined in this methd may be necessary fr reagent purificatin. 3.2 A methd blank must be run fr the cmpunds f interest prir t use f the methd. The interferences must be belw the methd detectin limit befre this methd is applied t actual samples. 4.0 APPARATUS AND MATERIALS 4.1 Drying clumn - 20 mm ID Pyrex chrmatgraphic clumn with Pyrex glass wl at bttm, r equivalent. NOTE: Fritted glass discs are difficult t clean after highly cntaminated extracts have been passed thrugh them. Clumns withut frits are recmmended. Use a small pad f Pyrex glass wl t retain the adsrbent. Prewash the glass wl pad with 50 ml f acetne fllwed by 50 ml f elutin slvent prir t packing the clumn with adsrbent. 4.2 Kuderna-Danish (K-D) apparatus Cncentratr tube - 10 ml graduated (Kntes K r equivalent). A grund glass stpper is used t prevent evapratin f the extracts Evapratin flask ml (K r equivalent). Attach t cncentratr tube with springs, clamps, r equivalent Snyder clumn - Three ball macr (Kntes K r equivalent) Snyder clumn - Tw ball micr (Kntes K r equivalent) Springs - 1/2 inch (Kntes K r equivalent). tps. 4.3 Vials - Glass, 2 ml capacity with Tefln lined screw-caps r crimp 4.4 Water bath - Heated, cncentric ring cver, temperature cntrl f + 2 C. Use this bath in a hd. CD-ROM 3650A - 2 Revisin 1

3 4.5 Biling chips - Slvent extracted, apprximately 10/40 mesh (silicn carbide r equivalent). 4.6 ph indicatr paper - ph range including the desired extractin ph. 4.7 Separatry funnel ml. 4.8 Erlenmeyer flask ml. 5.0 REAGENTS 5.1 Reagent grade inrganic chemicals shall be used in all tests. Unless therwise indicated, it is intended that all inrganic reagents shall cnfrm t the specificatins f the Cmmittee n Analytical Reagents f the American Chemical Sciety, where such specificatins are available. Other grades may be used, prvided it is first ascertained that the reagent is f sufficiently high purity t permit its use withut lessening the accuracy f the determinatin. 5.2 Organic-free reagent water - All references t water in this methd refer t rganic-free reagent water, as defined in Chapter One. 5.3 Sdium hydrxide, NaOH, (10N) - Disslve 40 g f sdium hydrxide in 100 ml f rganic-free reagent water. 5.4 Sulfuric acid, H SO, (1:1 v/v in water) - Slwly add 50 ml H SO t ml f rganic-free reagent water. 5.5 Sdium sulfate (granular, anhydrus), Na2SO 4 - Purify by heating at 400 C fr 4 hurs in a shallw tray, r by precleaning the sdium sulfate with methylene chlride. If the sdium sulfate is precleaned with methylene chlride, a methd blank must be analyzed, demnstrating that there is n interference frm the sdium sulfate. 5.6 Slvents: Methylene chlride, CH Cl - Pesticide quality r equivalent Acetne, CH COCH - Pesticide quality r equivalent Methanl, CH OH - Pesticide quality r equivalent Diethyl Ether, C H 0C H - Pesticide quality r equivalent Must be free f perxides as indicated by test strips (EM Quant, r equivalent). Prcedures fr remval f perxides are prvided with the test strips. After cleanup, 20 ml f ethyl alchl preservative must be added t each liter f ether. CD-ROM 3650A - 3 Revisin 1

4 6.0 SAMPLE COLLECTION, PRESERVATION, AND HANDLING 6.1 See the intrductry material t this chapter, Organic Analytes, Sectin PROCEDURE 7.1 Place 10 ml f the slvent extract frm a prir extractin prcedure int a 125 ml separatry funnel. 7.2 Add 20 ml f methylene chlride t the separatry funnel. 7.3 Slwly add 20 ml f prechilled rganic-free reagent water which has been previusly adjusted t a ph f with 10N sdium hydrxide. 7.4 Seal and shake the separatry funnel fr at least 2 minutes with peridic venting t release excess pressure. NOTE: Methylene chlride creates excessive pressure very rapidly; therefre, initial venting shuld be dne immediately after the separatry funnel has been sealed and shaken nce. The separatry funnel shuld be vented int a hd t prevent unnecessary expsure f the analyst t the rganic vapr. 7.5 Allw the rganic layer t separate frm the aqueus phase fr a minimum f 10 minutes. If the emulsin interface between layers is mre than ne-third the size f the slvent layer, the analyst must emply mechanical techniques t cmplete the phase separatin. The ptimum technique depends upn the sample, and may include stirring, filtratin f the emulsin thrugh glass wl, centrifugatin, r ther physical methds. 7.6 Separate the aqueus phase and transfer it t a 125 ml Erlenmeyer flask. Repeat the extractin tw mre times using 20 ml aliquts f dilute sdium hydrxide (ph 12-13). Cmbine the aqueus extracts. 7.7 Water sluble rganic acids and phenls will be primarily in the aqueus phase. Base/neutral analytes will be in the methylene chlride. If the analytes f interest are nly in the aqueus phase, discard the methylene chlride and prceed t Sectin 7.8. If the analytes f interest are nly in the methylene chlride, discard the aqueus phase and prceed t Sectin Externally cl the 125 ml Erlenmeyer flask with ice while adjusting the aqueus phase t a ph f 1-2 with sulfuric acid (1:1). Quantitatively transfer the cl aqueus phase t a clean 125 ml separatry funnel. Add 20 ml f methylene chlride t the separatry funnel and shake fr at least 2 minutes. Allw the methylene chlride t separate frm the aqueus phase and cllect the methylene chlride in an Erlenmeyer flask. 7.9 Add 20 ml f methylene chlride t the separatry funnel and extract at ph 1-2 a secnd time. Perfrm a third extractin in the same manner cmbining the extracts in the Erlenmeyer flask. CD-ROM 3650A - 4 Revisin 1

5 7.10 Assemble a Kuderna-Danish (K-D) cncentratr (if necessary) by attaching a 10 ml cncentratr tube t a 500 ml evapratin flask Dry bth acid and base/neutral fractins by passing them thrugh a drying clumn cntaining abut 10 cm f anhydrus sdium sulfate. Cllect the dried fractins in K-D cncentratrs. Rinse the Erlenmeyer flasks which cntained the slvents and the clumns with 20 ml f methylene chlride t cmplete the quantitative transfer Cncentrate bth acid and base/neutral fractins as fllws: Add ne r tw biling chips t the flask and attach a three ball macr-snyder clumn. Prewet the Snyder clumn by adding abut 1 ml f methylene chlride t the tp f the clumn. Place the K-D apparatus n a ht water bath (80-90 C) s that the cncentratr tube is partially immersed in the warm water. Adjust the vertical psitin f the apparatus and the water temperature as required t cmplete the cncentratin in minutes. At the prper rate f distillatin, the balls f the clumn will actively chatter but the chambers will nt fld. When the apparent vlume f liquid reaches 1 ml, remve the K-D apparatus frm the water bath and allw it t cl. Remve the Snyder clumn and rinse the flask and its lwer jints int the cncentratr tube with 1-2 ml f methylene chlride. Cncentrate the extract t the final vlume using either the micr- Snyder clumn technique (7.12.1) r nitrgen blwdwn technique (7.12.2) Micr-Snyder Clumn Technique Add anther ne r tw biling chips t the cncentratr tube and attach a tw ball micr-snyder clumn. Prewet the clumn by adding 0.5 ml f methylene chlride t the tp f the clumn. Place the K-D apparatus in a ht water bath (80-90 C) s that the cncentratr tube is partially immersed in the ht water. Adjust the vertical psitin f the apparatus and the water temperature as required t cmplete the cncentratin in 5-10 minutes. At the prper rate f distillatin the balls f the clumn will actively chatter but the chambers will nt fld. When the apparent vlume f the liquid reaches 0.5 ml, remve the K-D apparatus and allw it t cl. Remve the Snyder clumn and rinse the flask and its lwer jints int the cncentratr tube with 0.2 ml f methylene chlride. Adjust the final vlume t 1 ml with methylene chlride Nitrgen Blwdwn Technique Place the cncentratr tube in a warm water bath (35C) and evaprate the slvent vlume t ml using a gentle stream f clean, dry nitrgen (filtered thrugh a clumn f activated carbn). CAUTION: D nt use plasticized tubing between the carbn trap and the sample. CD-ROM 3650A - 5 Revisin 1

6 The internal wall f the cncentratr tube must be rinsed dwn several times with the apprpriate slvent during the peratin. During evapratin, the tube slvent level must be psitined t avid cndensatin water. Under nrmal prcedures, the extract must nt be allwed t becme dry. CAUTION: When the vlume f slvent is reduced belw 1 ml, semivlatile analytes may be lst The acid fractin is nw ready fr analysis. If the base/neutral fractin requires further cleanup by the alumina clumn cleanup fr petrleum waste (Methd 3611), the slvent may have t be changed t hexane. If a slvent exchange is required, mmentarily remve the Snyder clumn, add apprximately 5 ml f the exchange slvent and a new biling chip, and reattach the Snyder clumn. Cncentrate the extract as described in Sectin , raising the temperature f the water bath, if necessary, t maintain prper distillatin. When the apparent vlume again reaches 1 ml, remve the K-D apparatus frm the water bath and allw it t drain and cl fr at least 10 minutes. Repeat the exchange 2 mre times. If n further cleanup f the base/neutral extract is required, it is als ready fr analysis. 8.0 QUALITY CONTROL 8.1 Refer t Chapter One fr general quality cntrl prcedures and Methd 3600 fr cleanup prcedures. 8.2 The analyst must demnstrate that the cmpunds f interest are being quantitatively recvered befre applying this methd t actual samples. 8.3 Fr samples that are cleaned using this methd, the assciated quality cntrl samples must be prcessed thrugh this cleanup methd. 9.0 METHOD PERFORMANCE 9.1 Refer t the determinative methds fr perfrmance data REFERENCES 1. Test Methds: Methds fr Organic Chemical Analysis f Municipal and Industrial Wastewater; U.S. Envirnmental Prtectin Agency. Office f Research and Develpment. Envirnmental Mnitring and Supprt Labratry. ORD Publicatin Offices f Center fr Envirnmental Research Infrmatin: Cincinnati, OH, 1982; EPA-600/ CD-ROM 3650A - 6 Revisin 1

7 METHOD 3650A ACID-BASE PARTITION CLEANUP CD-ROM 3650A - 7 Revisin 1

8 METHOD 3650A (Cntinued) CD-ROM 3650A - 8 Revisin 1

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