Improving Productivity in Your Environmental and Food Testing Labs with Agilent 7890A/5975C GC/MS System

Transcription

1 Improving Productivity in Your Environmental and Food Testing Labs with Agilent 789A/5975C GC/MS System Mike Szelewski Senior Applications Chemist Page 1

2 Overview Capillary Flow Devices A family of tools for enhancing lab productivity Trace Analysis in Complex Mixtures Splitter provides element selective signals and MS spectra in a single injection PCBs in Fish Oil Deans switch removes cost and complexity from the analysis Semivolatiles Analysis QuickSwap reduces cycle time & keeps source clean Page 2

3 Pesticide Analysis Issues Trace level residue in complex matrices requires high instrument sensitivity and selectivity Multiple injections needed for selectivity/sensitivity (GC) and confirmation (MS) Desires shorter runtime to improve productivity Sometimes, a long bake-out period is needed to clean out heavy compounds Difficult to confirm targets in complex matrices Poor Spectral Library matches Long data processing time (background subtraction) Need to identify unknowns in samples Find all residues, fast! How many targets are in this sample and how long does it take to confirm? Page 3

4 Detector Splitter Example: --- Split column effluent to multiple detectors, even among MSD (vacuum) & GC detectors (atmospheric) 1:1:1 split DFPD:MSD:µECD ALS AUX EPC DualFPD µecd Effluent Splitter Column 5975C MSD 789A GC Page 4

5 Column Configuration GUI Simplifies Method Setup Page 5

6 Unknown peak in Strawberry Extract TIC No signal in fill-scan TIC µecd DualFPD (S) unknown DualFPD (P) Page 6

7 Deconvolution Reporting Software Finds All Target Compounds in 1-2 minutes Page 7

8 Target and Qualifier Ions of Temephos 2 Ion Ion Ion Ion Although the ion intensities are weak, the noticeable presence of all four ions at 4.9 min helped to identify the unknown peak as Temephos. Page 8

9 Milk Extract (MSD TIC) These high boilers are driven out of the split vent by backflushing at 28 o C Run time > 75 min to clean the column Oven ramps to 32 o C to bake off late eluters Page 9

10 Backflush During GC Run Split Vent S/SL Inlet 25 psi Aux EPC 4 psi Capillary Flow Device Detector(s) After GC Run Split Vent S/SL Inlet Aux EPC 6 psi Detector(s) 2 psi Capillary Flow Device Page 1

11 New ChemStation Software Makes it Easy to Set Up Backflushing Setting Up A Backflush Method Page 11

12 Blank Runs After 6 psi Blank run after a new injection and BF for 1 min Blank run after a new injection and BF for 2 min Blank run after a new injection and BF for 3 min Blank run after a new injection and BF for 4 min Blank run after a new injection and BF for 5 min Blank run after a new injection and BF for 6 min Blank run after a new injection and BF for 7 min Column is clean Note: late eluters were backflushed out first Page 12

13 Milk Extract It took additional 33 mins and column to 32 o C to remove these high boilers. Run stopped at 42 min and backflushed at 28 o C for 7 mins. Blank run after backflushing. Column is clean min Page 13

14 Summary The splitter configuration provides a comprehensive screening and quantitative system including SIM/Scan, µecd, DFPD(S and P) signals Backflush shortens cycle time and extends column life (The milk extract example shows the cycle time was reduced by more than 3%.) By combing Retention Time Locking (RTL) and the RTL pesticide database, a trace level pesticide residue was identified without the full scan mass spectrum Page 14

15 Background Information Fish are an excellent source of omega-3 fatty acids (DHA & EPA) American Heart Association recommends eating fatty fish at least two times per week or taking a daily fish oil supplement g of DHA + EPA /day significantly reduces deaths from heart disease and all causes But fish and fish oil may contain pollutants: PCBs, PBDEs, PCDDs, PCDFs, & heavy metals American Heart Association ( Page 15

16 Analysis of PCBs in Fish Oil The Challenges 29 possible PCB congeners No single-column method separates them all Indicator congeners measured in fish oil are: 28, 52, 11, 138, 153, 18 can be difficult to resolve from other PCBs Recommended method uses extraction followed by GC with High Resolution MS $$$$$ Problems when trying to GC fish oil High boilers stay on column causing: - carryover - dramatic shifts in PCB retention times Page 16

17 The Solution: Agilent 789A with Deans Switch for Heart Cutting and Backflushing ECD 1 No Cut restrictor solenoid valve (off) S/S Inlet PCM 41.4 psig 2.16 psig DB-XLB ECD 2 DB-2 Page 17

18 Solenoid Valve On for Heart Cutting Cut to Column 2 ECD 1 restrictor solenoid valve (on) S/S Inlet PCM 41.4 psig 2.16 psig DB-XLB ECD 2 DB-2 Page 18

19 Heart Cutting with the Deans Switch to Isolate Target PCBs from Fish Oil Spiked with Aroclor 126 Hz Hz 4 Column 2: DB-2 35 P/N ECD1 A, E CD1A, Fron t S ign al (CHUA NHONG FISH O IL DA TA JAN 2 7\ PCB \P CB 2-CA LIBRA TIO N IN IS O-OCTAN E Column 1: DB-XLB 3 P/N min Heart Cuts min Page 19

20 GC-FID Chromatogram of Fish Oil with No Backflushing 1-µL splitless injection of 1% fish oil without backflushing. GC oven was held at 29 o C for 3 min at the end of the run. g Enlarged Backflushing normally begins here Page 2

21 Two Blank Runs after 1-µL Splitless Injection of 1% Fish Oil Made with No Backflushing GC oven temperature held at 32 o C for 3 minutes at end of each run 1 st blank run 2 nd blank run Page 21

22 From a 35-Sample Sequence: Chromatograms 2, 2, & 35 Overlaid PCBs Spiked at.5 ppb Each Hz Hz min 11 Zoom At.5 ppb, PCB 28 is obscured by an interference in the Fish oil min Page 22

23 Quantitative Analysis of Indicator PCBs in a Real Fish Oil Sample (Un-spiked) Hz ppb ppb ppb ppb min Page 23

24 Summary For this application - No fish oil extraction saves time and $ - Low column maintenance - saves time and $ - HR/MS or HR/MS/MS not needed Saves ~ $4, More than 1 fish oil injections made without inlet or column maintenance Page 24

25 USEPA Method 827 Semivolatiles One of the most often used EPA methods Wastewater, soils and hazardous wastes Variations of this method account for >25% of environmental analyses Issues with currently available solutions Too slow with the commonly used 3m x 25um x.25um HP 5-MS Heavy matrix baked-out into source, necessitating frequent source cleaning (1-4 hours downtime) Daily front end column clips take.5-1. hr with cooling/re-heating the xfer line (which should be done to eliminate oxidizing the column) Oven cool down from 32C to 4C takes too long Page 25

26 Configuration and Results Configuration 2m x 18um x.36um DB 5.625, Agilent # faster runs QuickSwap for column maintenance/replacement without venting the 5975 or cooling the xfer line 5975 mounted in rear position of allows use of the pillow Method Criteria and Results, calibrated 1-2 ppm 827 criteria w/qs (range) 4 SPCCs minimum avg RRF CCCs %RSD < 3 % 2% - 2% Page 26

27 System Configuration Quick Swap with makeup gas 7683 Auto-sampler AUX EPC 5. psig 5975 MSD in back position 789A GC Column 2 m X.18 mm id X.36 µm DB Page 27

28 QuickSwap details Aux EPC In 5 psi during run 9 psi during backflush S/SL Inlet 25+ psi during run 1 psi during backflush MSD Transfer line Carrier/Aux flow Column flow During run Quick Swap restrictor During backflush Page 28

29 5 ppm 827 standard, run time 16 min. 77 analytes plus 6 ISTDs at 4 ppm Sample matrix forces a 4 min runtime baking heavies into source 24 min. Wasted 4 min. Backflush - spiked sample 2 min. Saved Scale 2x more sensitive than above Solvent injection after above 4 min backflush run. Inlet and column clean Page 29

30 Cycle Time Reduction = Productivity Gain Typical Minutes Saved Run Time without matrix bake-out, includes equib Run time with matrix bake-out 689 or QS Cool down time from 32 to Cool down time from 32 to 4 with pillow n/a Autosampler time, 789 with overlap Total time savings using a with the 2m column, Quick-Swap for backflush, rear postion for MSD and pillow Time Savings > 5 % Page 3

31 Conclusions Capillary Flow Technology Splitter, Deans switch, QuickSwap - extremely low dead volume - inert - does not leak - tracks oven temperature - easy column installation Backflushing preserves column lifetime, shortens cycle time and is made easy by the ChemStation software Can configure columns to Capillary Flow Devices and easily set pressures/flows 789A/5975C is extremely versatile! Page 31