Agilent GC/MS Analysis of PCBs in Waste Oil Using the Backflush Capability of the Agilent QuickSwap Accessory
Contents
1. Analysis of Suspected Flavor and Fragrance Allergens in Cosmetics Using the 7890A GC and Capillary Column Backflush 3 07 Agilent application note 5989 6460EN Bruce Quimby Rapid Forensic Toxicology Screening Using an Agilent 7890A NPD 5975 DRS GC MSD System 1 07 Agilent application note 5989 6066EN Mike Szelewski Significant Cycle Time Reduc tion Using the Agilent 7890A 5975 GC MSD for EPA Method 8270 2 07 Agilent application note 5989 6026EN Chunxiao Wang Parallel GC for Complete RGA Analysis 1 07 Agilent publication 5989 6103EN Philip Wylie Direct Injection of Fish Oil for the GC ECD Analysis of PCBs Results Using a Deans Switch With Backflushing 1 07 Agilent application note 5989 6095EN www agilent com chem For More Information For more information on our products and services visit our Web site at www agilent com chem Agilent shall not be liable for errors contained herein or for incidental or consequential damages in connection with the furnishing performance or use of this material Information descriptions and specifications in this publication are subject to change without notice Agilent Technologies Inc 2007 Printed in the USA November 7 2007 5989 7601EN 7 Agilent Technologies2. OP Tt 6 00 8 00 10 00 12 00 14 00 16 00 18 00 Time 20 00 22 00 24 00 26 00 28 00 Figure 3 GC MS TIC chromatograms obtained from scan data for a blank run after the analysis of a sampling with traditional bakeout no backflush A and with the use of backflush B Conclusion The benefits from using the backflush capability of QuickSwap on the 7890 GC MSD were illustrated using an analysis of PCBs in waste mineral oil The analytical portion of the analysis method was unchanged There were no negative consequences from adding a backflush to the method Several advantages were illustrated improved cycle time reduced column contamination improved pro jected column lifetime and reduced contamination of the MSD source Adding backflush to current methods should be seriously considered to increase both laboratory productivity and quality of results References 1 Information on sample preparation and analy sis of PCBs in waste oils can be found in refer ence methods DIN EN 12766 and DIN EN 61619 2 Chin Kai Meng Improving Productivity and Extending Column Life with Backflush 12 06 Agilent application note 5989 6018EN 3 Matthew S Klee Simplified Backflush Using Agilent 6890 GC 6 06 Agilent application note 5989 5111EN Matthew S Klee and Bruce Quimby A Column Flow Independent Configuration for Quick Swap 5 07 Agilent application note 5989 6702EN Frank David and Matthew S Klee
3. available specifically for this purpose According to EN 12766 for instance a combina tion of silica and acidified silica anion exchange SiOH H2SO SA adsorbents is prescribed The oil samples are diluted and applied to the cartridge in hexane solution and the PCB fraction is then immediately eluted with hexane rinse The polar matrix compounds remain on the SPE cartridges 1 In the PCB fraction however apolar matrix com pounds elute from the cartridge with the PCBs In one regard this is not an immediate analytical problem because when this sample fraction is ana lyzed by selective detectors like GC ECD or GC MS in selected ion monitoring SIM mode the co extracted solutes are not directly detected How ever their presence contaminates the inlet column and detector causing continuously decreasing system performance Symptoms such as drifting and increasingly noisy baseline integra tion difficulties decreasing chromatographic reso lution changing column selectivity and decreasing detector S N force more frequent inlet system column and MS source maintenance and poten tially require re running some samples Backflush is a technique that has recently become easier to implement with capillary GC separations due to the availability of Capillary Flow Technology devices 2 9 One such device is the Agilent Quick Swap whose primary function is to simplify a Agilent Technologies changing columns and doi
4. C min to 200 C 10 C min to 330 C 10 min Total run time 30 min Oven temperature program B with backflush 50 C 1 min 25 C min to 200 C 10 C min to 300 C 5 min Total run time 22 min MSD Setpoints 1 5 min solvent delay 260 C MSD transfer line SIM scan settings AutoTuned SIM ions 256 258 290 292 324 326 360 362 394 396 25 ms dwell time each Scan range 40 350 amu Table 2 Sample Sequence Run 1 Analysis of waste oil extract by GC MS in scan SIM mode no backflush oven program A Run 2 Blank run no sample injection no backflush oven program A same as run 1 Runs 3 5 Additional blank runs same conditions as above data not shown Run 6 Analysis of waste oil extract by GC MS in scan SIM mode with backflush oven program B Run7 Blank run no sample injection same program as in runs 1 5 Results temperature ramp and MS data acquisition are Total ion chromatograms TICs obtained from GC MS SIM mode are shown in Figure 1 tradi tional bakeout with no backflush A with back flush B The PCBs of interest elute in the 9 to 16 min time range The profiles obtained by both methods are very similar in PCB resolution and intensity When these results are carefully scruti nized little or no difference is noted However a clear baseline drop is observed in chromatogram B at 16 5 min corresponding to the initiation of backflush In usua
5. GC MS Analysis of PCBs in Waste Oil i Using the Backflush Capability of the gt Agilent QuickSwap Accessory A Environmental e e Authors Frank David Research Institute for Chromatography Pres Kennedypark 26 8500 Kortrijk Belgium Matthew S Klee Agilent Technologies 2850 Centerville Road Wilmington DE 19808 USA Abstract Polychlorinated biphenyls PCBs in waste oil are typi cally analyzed by GC ECD or GC MS after solid phase extraction SPE cleanup However not all problematic matrix components are completely removed during cleanup and are injected into the analytical system thereby contaminating the column and the detector In this application a practical example of backflushing is presented using the Agilent QuickSwap accessory installed on a 7890 GC 5975 MSD system Benefits of using QuickSwap instead of the traditional high tempera ture bakeout procedure are demonstrated Column and detector contamination were significantly reduced and sample throughput increased Introduction The determination of polychlorinated biphenyls PCBs in mineral oils including transformer oil Application waste oil or solid waste in general is a routine application in environmental laboratories After dilution dissolution of the oil sample a solid phase extraction sample cleanup is used to remove most of the matrix components Several SPE meth ods are commonly applied and some custom car tridges are
6. an data with which to identify unknowns using a library search or spectral interpretation For the same analytical runs shown in Figure 1 based on SIM data total ion chromatograms from full scan data are shown in Figure 2A no backflush and Figure 2B with backflush The sample matrix interferents can be even more easily seen in these chromatograms Since all ions in the 40 to 350 amu range are being monitored the considerable amounts of material eluting after the PCBs of interest dominates the chromatogram In fact in the TICs shown in Figure 2 the low level PCBs are not discernable due to the dominance of the hydrocarbon back ground It appears that all the interferents were effectively removed by the bakeout because the signal returns to baseline even though this was not the case To better demonstrate the inferiority of traditional bakeout to backflushing for removing residual Abundance 2e 074 TIC exp3 6 D DATA MS 4 TIC exp3 1 D DATA MS 1 5e 07 1e 07 J PCB elution range components a blank run no injection was made after each of the analytical runs previously shown The TIC scan mode chromatogram after sample analysis with bakeout is shown in Figure 3A To contrast the efficacy of backflush in removing con tamination the blank run done directly after sample analysis with backflush is shown in Figure 3B In this chromatograph only signal from normal column bleed was observed In F
7. igure 3A the higher level of contamination was seen even after doing the 10 min bakeout at 330 C and observing the apparent return of signal back to baseline From this comparison it is a clear that by relying on a typical bakeout low volatility material would continue to build up in the analytical system from run to run ever increasing the level of back ground and interfering with subsequent analyses requiring the column to be prematurely replaced By backflushing the low volatility material was efficiently removed at lower temperatures in less time while simultaneously lowering source conta mination Column lifetime would improve dramati cally In addition the backflush method required less cooldown time after the run from 300 C instead of 330 C Total cycle time was thereby reduced by more than 25 by using backflush A Traditional bakeout at 330 C for 10 min B With backflush at 300 C 1 for 5 min 5000000 Ti pt tip iio tot rbd be ha oe a he oe op ep oo EP ee 6 00 8 00 10 00 12 00 14 00 16 00 18 00 20 00 22 00 24 00 26 00 28 00 Time Figure 2 GC MS TIC scan chromatograms obtained for the analysis of PCBs in waste mineral oil without back flush A and with backflush B Abundance oa o li 450000 400000 TIC exp3 7 D DATA MS 350000 TIC exp3 2 D DATA MS 300000 250000 200000 150000 100000 50000 ar A No BF B With BF
8. l backflush methods the oven Abundance 200000 150000 100000 50000 50000 100000 150000 200000 ere can stopped when backflush is initiated In Figure 1B oven temperature was held at 300 C but acquisi tion was left on to show the drop in baseline when column flow reversed In contrast to the backflush chromatogram B a hump is observed extending to 22 min in chromatogram A This shows the pres ence of high boiling matrix interferences in the sample extract and demonstrates the need for removal of these either through a bakeout or back flush By the end of the bakeout in 1B the baseline appears to return to the initial level indicating that the interferences had been removed TIC exp3 6 D DATASIM MS TIC exp3 1 D DATASIM MS A Traditional bakeout at high temperature B With backflush at 300 C 6 00 8 00 10 00 12 00 14 00 16 00 18 00 Time Figure 1 backflush A and with backflush B 20 00 22 00 24 00 26 00 28 00 GC MS total ion chromatograms TICs obtained for the analysis of PCBs in waste mineral oil without A helpful recent enhancement of Agilent MSDs is the ability to acquire both SIM and scan data in the same run termed simultaneous SIM Scan The advantage of simultaneous SIM Scan is that the benefits of improved detection limits for target compounds with SIM acquisition can be coupled with the benefit of having full sc
9. mination is reduced Sample Preparation A typical procedure was used to prepare a BCR reference sample BCR 449 waste mineral oil high PCB level A 10 dilution of the oil was made in hexane 1 gin 10 mL From this solution 250 uL was applied to a series combination of two car tridges a 3 mL cartridge filled with 500 mg of silica treated with H2SO 500 mg strong anion exchange resin and a 3 mL cartridge filled with 500 mg silica The cartridges were preconditioned with hexane The PCBs were eluted with 4 mL hexane An aliquot of this solution was used for GC MS analyses GC Conditions All analyses were performed on an Agilent 7890A GC 5975 MSD system with QuickSwap option number 113 with Aux EPC module Injection was done using a 7683 ALS The GC MS conditions can be summarized in Table 1 Column 30 m x 0 25 mm id x 0 25 um df HP 5MS Agilent P N 19091 433 Inlet S Sl in splitless mode 280 C 0 75 min purge delay Purge flow rate 50 mL min Carrier gas Helium Run pressure Backflush pressure 150 kPa constant pressure 28 kPa 2 mL min initial flow rate QuickSwap Restrictor GC option number 113 or 17 cm x 110 pm id restrictor Accessory kit G3185B Part number G3185 60363 Column outlet QuickSwap Run pressure Backflush pressure Helium 28 kPa He using AUX EPC 150 kPa Through elution of PCBs Held for 5 min after PCBs Oven temperature program A no backflush 50 C 1 min 25
10. ng maintenance on GC MS systems QuickSwap provides a flow of clean carrier gas that excludes air from the mass spectrometer when columns are disconnected An auxiliary electronic pressure control aux EPC module or pressure control module PCM is typi cally used to supply the purge gas to QuickSwap and thereby offers the ability to program the pres sure during the run To backflush a capillary column one need only raise the pressure of Quick Swap the outlet of the column higher than that of the inlet the head of the column The column flow reverses eliminating remaining sample com ponents from the head of the column and passing them out of the split vent of the inlet and onto the split vent trap Backflushing a column after elution of the com pounds of interest is a very effective way of elimi nating column contamination Low volatility contaminants from the most recently injected sample tend to remain at the head of the column until high oven temperatures are reached So by reversing the flow through the column these con taminants need only flow a short distance to be removed from the column In the traditional bake out they would need to travel through the full Table 1 GC MS System Conditions length of the column to be removed In addtion to more effective removal of contaminants cycle time is significantly reduced columns are spared from exposure to the high temperatures typical of bake outs and detector conta
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Agilent GC/MS Analysis of PCBs in Waste Oil Using the Backflush Capability of the Agilent QuickSwap