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H&P Mobile GeoChemistry Escondido, CA TO-15 or not TO-15? James Picker, Ph.D. That is the question.

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Presentation on theme: "H&P Mobile GeoChemistry Escondido, CA TO-15 or not TO-15? James Picker, Ph.D. That is the question."— Presentation transcript:

1 H&P Mobile GeoChemistry Escondido, CA TO-15 or not TO-15? James Picker, Ph.D. That is the question.

2 H&P Mobile GeoChemistry Escondido, CA Objective Used for the analysis of VOCs in soil vapor (gas) to measure health risk Compare/Contrast EPA Method 8260B vs. EPA Method TO-15/TO-14A

3 H&P Mobile GeoChemistry Escondido, CA OR Perceived (advertised?) Difference

4 H&P Mobile GeoChemistry Escondido, CA OR Actual difference

5 H&P Mobile GeoChemistry Escondido, CA Summary EPA 8260 vs. TO-15/14A SAMEIDENTICAL Data ReductionGC/MS SystemSample Preparation SLIGHTLY DIFFERENT

6 H&P Mobile GeoChemistry Escondido, CA Similarities GC/MS Method (SCAN or SIM) GC with FSCC (20-60m X mm id) LRMS (quadrupole, ion trap, TOF) *Concentration of compounds on multiadsorbent trap* Uses Internal Standards/Surrogate(s) for accuracy/QC Multipoint Calibration ICAL, linearity checks, Daily CCV Varying sample size permitted Quant by RFs

7 H&P Mobile GeoChemistry Escondido, CA Differences Standards and Sample Preparation EPA 8260B (modified) *Standards in liquid (MeOH)* Purge and trap Purged from headspace and H2O using He or dry purging Water management Desorption direct to GC/MS EPA TO-15/14A *Standards in Air (N2)* Vacuum (or Pressure) flow and Trap pulled from cylinder, using pump or pressure Desorption to cryofocus or directly to GC/MS.

8 H&P Mobile GeoChemistry Escondido, CA Standards in Water or Air -

9 H&P Mobile GeoChemistry Escondido, CA Compounds Analyzed equally well by EPA 8260 or TO-15 BTEX, Trimethylbenzenes, Freons PCE, TCE, vinyl chloride, DCEs, 1,2- DCPE, 1,1,1,2- TCA 1,1,1-TCA,

10 H&P Mobile GeoChemistry Escondido, CA Compounds Analyzed with a slight high bias by EPA 8260 versus TO-15 MTBE, other oxygenates 1,1,2,2-TCA, 1,2- DCA, 1,1,2-TCA Naphthalene rest of common 8260 list

11 H&P Mobile GeoChemistry Escondido, CA Compounds Analyzed with a high bias by EPA 8260 versus TO-15 Ethanol, TBA 1,4 Dioxane Acetone & other ketones Any water soluble low volatility compound

12 H&P Mobile GeoChemistry Escondido, CA Differences II Calibration and Range EPA 8260B (modified) Typical Calibration 500 – ug/m3 ( ppbv for benzene) MDLs 100 ug/m3 (31 ppbv benzene) For 8260 SIM 10 ug/m3 (3 ppbv benzene EPA TO-15/14A Typical Calibration ug/m3 benzene (1-40 ppbv) MDLs 0.3 ug/m3 benzene( 0.1ppbv) For TO-15 SIM 0.03 ug/m3 benzene (0.01ppbv)

13 H&P Mobile GeoChemistry Escondido, CA Calibration Range MDL to highest standard assumes 20 cc sample ug/m3 TO-15/14A SIM 8260 SCAN TO-15/14A SCAN 8260 SIM Normal Range Extended by dilution

14 H&P Mobile GeoChemistry Escondido, CA Fail Levels subslab 5bgs ug/m3 TO-15/14A SIM 8260 SCAN TO-15/14A SCAN 8260 SIM EPA R9 CA-EPA

15 H&P Mobile GeoChemistry Escondido, CA ug/m3 TO-15/14A SIM 8260 SCAN TO-15/14A SCAN 8260 SIM Fail Levels subslab 5bgs CA EPAEPA R9

16 H&P Mobile GeoChemistry Escondido, CA Project BL 4FEB05 results in ug/L SampleTO-15 PCE 8260 PCE TO-15 TCE 8260 TCE TO-15 c12DCE 8260 c12DCE TO-15 t12DCE 8260 t12DCE TO-15 F F-113 SV < SV SV < SV <1 SV < SV < SV < SV < AVG %Diff Average % Diff across all compounds = 38%

17 H&P Mobile GeoChemistry Escondido, CA Project MC 1FEB05 results in ppbv SampleTO-15 PCE 8260 PCE TO-15 TCE 8260 TCE TO-15 c12DCE 8260 c12DCE TO TCA TCA TO-15 F F-113 SG <16<2532<25<16<25NA SG <16<254036NA SG8<16<14<1664<16< NA SG12<16< NA SG1329<149881<16<2528<20NA

18 H&P Mobile GeoChemistry Escondido, CA Conclusions 1.For most vapor intrusion compounds of interest, methods yield identical results 2.For more water soluble compounds 8260 is within factor of 2. Fine for VI calculations 3.A few compounds may require TO method. Some compounds may require 8260 method 4.On-site analysis assists in decision making, regulatory QA requirements and assurance of tracer compound integrity

19 H&P Mobile GeoChemistry Escondido, CA Recommendations Choose either or a combination of methods, depending on compounds and DLs required Select on-site analysis for decision making, regulatory QA requirements (assurance of tracer compound integrity, purge volume testing, etc.) Do onsite TO-15 where levels are low Do onsite 8260 where levels are moderate to high Follow with offsite TO-15 for Quality Assurance

20 H&P Mobile GeoChemistry Escondido, CA

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22 H&Ps Solutions Option 1 – Where 8260B Meets Project DQOs: On-site, full QC 8260B fulfilling DTSC/LA-RWQCB requirements with off-site TO- 15 confirmation on a sub-set of samples. Option 2 – Where TO-14/15 is required to meet Project DQOs: On-site screening-level 8260B of all samples with of-site analysis of ALL samples by TO-15. Option 3 – For larger projects with lower DLs: On site TO-15 All Options: Fulfill all DTSC soil gas advisory requirements Allow on-site analysis for leak/tracer compound test Guarantee sample integrity Provide real-time data for real-time decisions

23 James Picker, Ph.D. 148 Vinewood Street Escondido, CA (800)


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