METHOD 5040A ANALYSIS OF SORBENT CARTRIDGES FROM VOLATILE ORGANIC SAMPLING TRAIN (VOST): GAS CHROMATOGRAPHY/MASS SPECTROMETRY TECHNIQUE

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1 METHOD 5040A ANALYSIS OF SORBENT CARTRIDGES FROM VOLATILE ORGANIC SAMPLING TRAIN (VOST): GAS CHROMATOGRAPHY/MASS SPECTROMETRY TECHNIQUE 1.0 SCOPE AND APPLICATION 1.1 Methd 5040 was frmerly Methd 3720 in the Secnd Editin f this manual. 1.2 This methd cvers the determinatin f vlatile principal rganic hazardus cnstituents (POHCs), cllected n Tenax and Tenax/charcal srbent cartridges using a vlatile rganic sampling train, VOST (1). Much f the descriptin fr purge-and-trap GC/MS analysis is described in Methd 8240 f this chapter. Because the majrity f gas streams sampled using VOST will cntain a high cncentratin f water, the analytical methd is based n the quantitative thermal desrptin f vlatile POHCs frm the Tenax and Tenax/charcal traps and analysis by purge-and-trap GC/MS. Fr the purpses f definitin, vlatile POHCs are thse POHCs with biling pints less than 100 C. 1.3 This methd is applicable t the analysis f Tenax and Tenax/ charcal cartridges used t cllect vlatile POHCs frm wet stack gas effluents frm hazardus waste incineratrs. 1.4 The sensitivity f the analytical methd fr a particular vlatile POHC depends n the level f interferences and the presence f detectable levels f vlatile POHCs in blanks. The desired target detectin limit f the analytical methd is 0.1 ng/l (20 ng n a single pair f traps) fr a particular vlatile POHC desrbed frm either a single pair f Tenax and Tenax/charcal cartridges r by thermal desrptin f up t six pairs f traps nt a single pair f Tenax and Tenax/charcal traps. The resulting single pair f traps is then thermally desrbed and analyzed by purge-and-trap GC/MS. 1.5 This methd is recmmended fr use nly by experienced mass spectrscpists r under the clse supervisin f such qualified persns. 2.0 SUMMARY OF METHOD 2.1 A schematic diagram f the analytical system is shwn in Figure 1. The cntents f the srbent cartridges are spiked with an internal standard and thermally desrbed fr 10 min at 180 C with rganic-free nitrgen r helium gas (at a flw rate f 40 ml/min), bubbled thrugh 5 ml f rganic-free reagent water, and trapped n an analytical adsrbent trap. After the 10 min. desrptin, the analytical adsrbent trap is rapidly heated t 180 C, with the carrier gas flw reversed s that the effluent flw frm the analytical trap is directed int the GC/MS. The vlatile POHCs are separated by temperature prgrammed gas chrmatgraphy and detected by lw-reslutin mass spectrmetry. The cncentratins f vlatile POHCs are calculated using the internal standard technique. CD-ROM 5040A - 1 Revisin 1

2 3.0 INTERFERENCES 3.1 Refer t Methds 3500 and APPARATUS AND MATERIALS 4.1 Thermal desrptin unit: The thermal desrptin unit (fr Inside/Inside VOST cartridges, use Supelc "clamshell" heater; fr Inside/Outside VOST cartridges, user-fabricated unit is required) shuld be capable f thermally desrbing the srbent resin tubes. It shuld als be capable f heating the tubes t C with flw f rganic-free nitrgen r helium thrugh the tubes. 4.2 Purge-and-trap unit: The purge-and-trap unit cnsists f three separate pieces f equipment: the sample purger, trap, and the desrber. It shuld be capable f meeting all requirements f Methd 5030 fr analysis f purgeable rganic cmpunds frm water. 4.3 GC/MS system: As described in Methd REAGENTS 5.1 Organic-free reagent water. All references t water in this methd refer t rganic-free reagent water, as defined in Chapter One. 5.2 Methanl, CH OH - Pesticide grade, r equivalent Analytical trap reagents: ,6-Diphenylene xide plymer: Tenax (60/80 mesh), chrmatgraphic grade r equivalent Methyl silicne packing: 3% OV-1 n Chrmsrb W (60/80 mesh) r equivalent Silica gel: Davisn Chemical (35/00 mesh), Grade 15, r equivalent Charcal: Petrleum-based (SKC Lt 104 r equivalent). 5.4 Stck standard slutin: Stck standard slutins will be prepared frm pure standard materials r purchased as certified slutins. The stck standards shuld be prepared in methanl using assayed liquids r gases, as apprpriate. Because f the txicity f sme f the rganhalides, primary dilutins f these materials shuld be prepared in a hd. A NIOSH/MESA apprved txic CD-ROM 5040A - 2 Revisin 1

3 gas respiratr shuld be used when the analyst handles high cncentratins f such materials Fresh stck standards shuld be prepared weekly fr vlatile POHCs with biling pints f <35 C. All ther standards must be replaced mnthly, r sner if cmparisn with check standards indicates a prblem. 5.5 Secndary dilutin standards: Using stck standard slutins, prepare, in methanl, secndary dilutin standards that cntain the cmpunds f interest, either singly r mixed tgether. The secndary dilutin standards shuld be prepared at cncentratins such that the desrbed calibratin standards will bracket the wrking range f the analytical system Brmflurbenzene (BFB) standard: Prepare a 25 ng/µl slutin f BFB in methanl. 5.7 Deuterated benzene: Prepare a 25 ng/µl slutin f benzene-d in methanl SAMPLE COLLECTION, PRESERVATION, AND HANDLING 6.1 Refer t Methd 0030, Chapter Ten. 6.2 Sample trains btained frm the VOST shuld be analyzed within 2-6 weeks f sample cllectin. 7.0 PROCEDURE 7.1 Assembly f PTD device: Assemble a purge-and-trap desrptin device (PTD) that meets all the requirements f Methd 5030 (refer t Figure 1) Cnnect the thermal desrptin device t the PTD device. Calibrate the PTD-GC/MS system using the internal standard technique. 7.2 Internal standard calibratin prcedure: This apprach requires the use f deuterated benzene as the internal standard fr these analyses. Other internal standards may be prpsed fr use in certain situatins. The imprtant criteria fr chsing a particular cmpund as an internal standard are that it be similar in analytical behavir t the cmpunds f interest and that it can be demnstrated that the measurement f the internal standard be unaffected by methd r matrix interferences. Other internal standards that have been used are ethylbenzene-d 10 and, 1-2-dichlrethane-d 4. One adds 50 ng f BFB t all srbent cartridges (in additin t ne r mre CD-ROM 5040A - 3 Revisin 1

4 internal standards) t prvide cntinuus mnitring f the GC/MS perfrmance relative t BFB Prepare calibratin standards at a minimum f three cncentratin levels fr each analyte f interest The calibratin standards are prepared by spiking a blank Tenax r Tenax/charcal trap with a methanlic slutin f the calibratin standards (including 50 ng f the internal standard, such as deuterated benzene), using the flash evapratin technique. The flash evapratin technique requires filling the needle f a 5.0 µl syringe with clean methanl and drawing air int the syringe t the 1.0 µl mark. This is fllwed by drawing a methanlic slutin f the calibratin standards (cntaining 25 µg/µl f the internal standard) t the 2.0 µl mark. The glass traps shuld be attached t the injectin prt f a gas chrmatgraph while maintaining the injectr temperature at 160 C. The carrier gas flw thrugh the traps shuld be maintained at abut 50 ml/min After directing the gas flw thrugh the trap, the cntents f the syringe shuld be slwly expelled thrugh the gas chrmatgraph injectin prt ver abut 15 sec. After 25 sec have elapsed, the gas flw thrugh the trap shuld be shut ff, the syringe remved, and the trap analyzed by the PTD-GC/MS prcedure utlined in Methd The ttal flw f gas thrugh the traps during additin f calibratin standards t blank cartridges, r internal standards t sample cartridges, shuld be 25 ml r less Analyze each calibratin standard fr bth Tenax and Tenax/ charcal cartridges accrding t Sectin 7.3. Tabulate the area respnse f the characteristic ins f each analyte against the cncentratin f the internal standard and calculate the respnse factr (RF) fr each cmpund, using Equatin 1. where: RF = AsC is/aisc s (1) A = s A = is C = is C = s Area f the characteristic in fr the analyte t be measured. Area f the characteristic in fr the internal standard. Amunt (ng) f the internal standard. Amunt (ng) f the vlatile POHC in calibratin standard. If the RF value ver the wrking range is a cnstant (<10% RSD), the RF can be assumed t be invariant, and the average RF can be used fr calculatins. Alternatively, the results can be used t plt a calibratin curve f respnse ratis, A s/a is versus RF. CD-ROM 5040A - 4 Revisin 1

5 7.2.6 The wrking calibratin curve r RF must be verified n each wrking day by the measurement f ne r mre f the calibratin standards. If the respnse varies by mre than +25% fr any analyte, a new calibratin standard must be prepared and analyzed fr that analyte. 7.3 The schematic f the PTD-GC/MS system is shwn in Figure 1. The sample cartridge is placed in the thermal desrptin apparatus (fr Inside/ Inside VOST cartridges, use Supelc "clamshell" heater; fr Inside/Outside VOST cartridges, user fabricated unit is required) and desrbed in the purge-and-trap system by heating t 180C fr 10 min at a flw rate f 40 ml/min. The desrbed cmpnents pass int the bttm f the water clumn, are purged frm the water, and cllected n the analytical adsrbent trap. After the 10 min desrptin perid, the cmpunds are desrbed frm the analytical adsrbent trap int the GC/MS system accrding t the prcedures described in Methd Qualitative analysis The qualitative identificatin f cmpunds determined by this methd is based n retentin time, and n cmparisn f the sample mass spectrum, after backgrund crrectin, with characteristic ins in a reference mass spectrum. The reference mass spectrum must be generated by the labratry using the cnditins f this methd. The characteristic ins frm the reference mass spectrum are defined t be the three ins f greatest relative intensity, r any ins ver 30% relative intensity if less than three such ins ccur in the reference spectrum. Cmpunds shuld be identified as present when the criteria belw are met The intensities f the characteristic ins f a cmpund maximize in the same scan r within ne scan f each ther. Selectin f a peak by a data system target cmpund search rutine, where the search is based n the presence f a target chrmatgraphic peak cntaining ins specific fr the target cmpund at a cmpund-specific retentin time, will be accepted as meeting this criterin The RRT f the sample cmpnent is within ± 0.06 RRT units f the RRT f the standard cmpnent The relative intensities f the characteristic ins agree within 30% f the relative intensities f these ins in the reference spectrum. (Example: Fr an in with an abundance f 50% in the reference spectrum, the crrespnding abundance in a sample spectrum can range between 20% and 80%.) Structural ismers that prduce very similar mass spectra shuld be identified as individual ismers if they have sufficiently different GC retentin times. Sufficient GC reslutin is achieved if the height f the valley between tw ismer peaks is less than 25% f the sum f the tw peak heights. Otherwise, structural ismers are identified as ismeric pairs Identificatin is hampered when sample cmpnents are nt reslved chrmatgraphically and prduce mass spectra CD-ROM 5040A - 5 Revisin 1

6 cntaining ins cntributed by mre than ne analyte. When gas chrmatgraphic peaks bviusly represent mre than ne sample cmpnent (i.e., a bradened peak with shulder(s) r a valley between tw r mre maxima), apprpriate selectin f analyte spectra and backgrund spectra is imprtant. Examinatin f extracted in current prfiles f apprpriate ins can aid in the selectin f spectra, and in qualitative identificatin f cmpunds. When analytes celute (i.e., nly ne chrmatgraphic peak is apparent), the identificatin criteria can be met, but each analyte spectrum will cntain extraneus ins cntributed by the celuting cmpund Fr samples cntaining cmpnents nt assciated with the calibratin standards, a library search may be made fr the purpse f tentative identificatin. The necessity t perfrm this type f identificatin will be determined by the type f analyses being cnducted. Guidelines fr making tentative identificatin are: (1) Relative intensities f majr ins in the reference spectrum (ins > 10% f the mst abundant in) shuld be present in the sample spectrum. (2) The relative intensities f the majr ins shuld agree within + 20%. (Example: Fr an in with an abundance f 50% in the standard spectrum, the crrespnding sample in abundance must be between 30 and 70%). (3) Mlecular ins present in the reference spectrum shuld be present in the sample spectrum. (4) Ins present in the sample spectrum but nt in the reference spectrum shuld be reviewed fr pssible backgrund cntaminatin r presence f celuting cmpunds. (5) Ins present in the reference spectrum but nt in the sample spectrum shuld be reviewed fr pssible subtractin frm the sample spectrum because f backgrund cntaminatin r celuting peaks. Data system library reductin prgrams can smetimes create these discrepancies. Cmputer generated library search rutines shuld nt use nrmalizatin rutines that wuld misrepresent the library r unknwn spectra when cmpared t each ther. Only after visual cmparisn f the sample with the nearest library searches will the mass spectral interpretatin specialist assign a tentative identificatin. 7.5 Quantitative analysis When an analyte has been qualitatively identified, quantitatin shuld be based n the integrated abundance frm the EICP f the primary characteristic in chsen fr that analyte. If the sample prduces an interference fr the primary characteristic in, a secndary characteristic in shuld be used. CD-ROM 5040A - 6 Revisin 1

7 Using the internal standard calibratin prcedure, the amunt f analyte in the sample cartridge is calculated using the respnse factr (RF) determined in Sectin and Equatin 2. where: Amunt f POHC = AsC is/aisrf (2) A = Area f the characteristic in fr the analyte t be s measured. A = Area fr the characteristic in f the internal is standard. C = Amunt (ng) f internal standard. is The chice f methds fr evaluating data cllected using VOST fr incineratr trial burns is a regulatry decisin. The prcedures used extensively by ne user are utlined belw The ttal amunt f the POHCs f interest cllected n a pair f traps shuld be summed The bservatin f high cncentratins f POHCs f interest in blank cartridges indicates pssible residual cntaminatin f the srbent cartridges prir t shipment t and use at the site. Data that fall in this categry (especially data indicating high cncentratins f POHCs in blank srbent cartridges) shuld be qualified with regard t validity, and blank data shuld be reprted separately. The applicability f data f this type t the determinatin f DRE is a regulatry decisin. Cntinued bservatin f high cncentratins f POHCs in blank srbent cartridges indicates that prcedures fr cleanup, mnitring, shipment, and strage f srbent cartridges by a particular user be investigated t eliminate this prblem If any internal standard recveries fall utside the cntrl limits established in Sectin 8.4, data fr all analytes determined fr that cartridge(s) must be qualified with the bservatin. 8.0 QUALITY CONTROL 8.1 Refer t Chapter One fr specific quality cntrl prcedures and Methd 0030 fr sample preparatin prcedures. 8.2 Each labratry that uses this methd is required t perate a frmal quality cntrl prgram. The minimum requirements f this prgram cnsist f an initial demnstratin f labratry capability and the analysis f blank Tenax and Tenax/charcal cartridges spiked with the analytes f interest. The labratry is required t maintain perfrmance recrds t define the quality f CD-ROM 5040A - 7 Revisin 1

8 data that are generated. Onging perfrmance checks must be cmpared with established perfrmance criteria t determine if results are within the expected precisin and accuracy limits f the methd Befre perfrming any analyses, the analyst must demnstrate the ability t generate acceptable precisin and accuracy with this methd. This ability is established as described in Sectin The labratry must spike all Tenax and Tenax/charcal cartridges with the internal standard(s) t mnitr cntinuing labratry perfrmance. This prcedure is described in Sectin T establish the ability t generate acceptable accuracy and precisin, the analyst must spike blank Tenax and Tenax/charcal cartridges with the analytes f interest at tw cncentratins in the wrking range The average respnse factr (RF) and the standard deviatin (s) fr each must be calculated The average recvery and standard deviatin must fall within the expected range fr determinatin f vlatile POHCs using this methd. The expected range fr recvery f vlatile POHCs using this methd is %. 8.4 The analyst must calculate methd perfrmance criteria fr the internal standard(s) Calculate upper and lwer cntrl limits fr methd perfrmances using the average area respnse (A) and standard deviatin(s) fr internal standard: Upper Cntrl Limit (UCL) = A + 3s Lwer Cntrl Limit (LCL) = A - 3s The UCL and LCL can be used t cnstruct cntrl charts that are useful in bserving trends in perfrmance. The cntrl limits must be replaced by methd perfrmance criteria as they becme available frm the U.S. EPA. 8.5 The labratry is required t spike all sample cartridges (Tenax and Tenax/charcal) with internal standard. 8.6 Each day, the analyst must demnstrate thrugh analysis f blank Tenax and Tenax/charcal cartridges and rganic-free reagent water that interferences frm the analytical system are under cntrl. 8.7 The daily GC/MS perfrmance tests required fr this methd are described in Methd METHOD PERFORMANCE 9.1 Refer t the determinative methds fr perfrmance data. CD-ROM 5040A - 8 Revisin 1

9 10.0 REFERENCES 1. Prtcl fr Cllectin and Analysis f Vlatile POHC's Using VOST. EPA/600/ , March Validatin f the Vlatile Organic Sampling Train (VOST) Prtcl. Vlumes I and II. EPA/600/ a, January CD-ROM 5040A - 9 Revisin 1

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11 METHOD 5040A ANALYSIS OF SORBENT CARTRIDGES FROM VOLATILE ORGANIC SAMPLING TRAIN (VOST): GAS CHROMATOGRAPHY/MASS SPECTROMETRY TECHNIQUE CD-ROM 5040A - 11 Revisin 1