Optimum methods for the analysis of 1,4-dioxane and the potential for false positives

1. Optimum methods for the analysis of 1,4-dioxane and the potential for false positives Charles Carter, Ph.D. Vice President of Quality and Technical Services September 16, 2014

2. Topics Background on 1,4-dioxane as an environmental contaminant Basic chemistry of 1,4-dioxane A story Optimum methods for the analysis of 1,4-dioxane Field sampling issues that can create false positives for 1,4-dioxane Another story Sample and laboratory conditions that can create false positives for 1,4-dioxane Achieving standard reporting limits with reduced volume samples An update

3. Background Regulatory levels in between 1 ppb and 3 ppb EPA clu-in site indicated detection in 73 of 702 sources sampled in California Above action limit in 28 of these sources 67 sites in New Hampshire with concentrations from 2 ppb to 11,000 ppb Probable human carcinogen Used as a solvent stabilizer, as a solvent in various chemical processes, and is present as a by product in a variety of other materials.

4. Chemistry • Formula and structure • C4H8O2 • Boiling point 101.1 C • Infinitely water miscible • Miscible with most organic solvents • Boiling point in the range of standard volatiles, e.g toluene boils at 110 C • Low Henry’s Law constant due to miscibility with water. Fairly volatile in pure form, not very volatile from water.

5. Story #1 • Site contaminated with trichloroethene • Years of monitoring • Abrupt appearance of 1,4-dioxane at concentrations up to 800 ppb, field blanks and laboratory blanks clean • Data made no sense, but now 1,4-dioxane was the major risk driver • Please review the data • Perfect • Please check for contamination • None • Please reanalyze the samples and have a separate analysis done in a different lab • Same results • Now what?

6. Optimum method Some criticism from EPA on method choice 8260 or 8270, SIM or full scan? Poor purge efficiency, but poor extraction efficiency as well Poor purge efficiency accounted for in calculation of response factor Is purge efficiency consistent and largely independent of matrix? Lots of opinions! Let’s get some data.

7. Results Pulled all matrix spike results for a 10 month period

8. Test any materials in contact with the sample SPLP extracts of well casing, well fittings, gloves, cleaning solutions, and other materials (in Edison) Analysis by 8260 SIM with heated purge (in Irvine) Numerous materials leached 1,4-dioxane including nylon fittings and the FLUTe well liner Only those materials that had been either leak checked or washed prior to use showed contamination The leak checks were done with Dawn dishwashing detergent, and the field equipment decontamination was done with an old bottle labeled Alconox.

9. 1,4-dioxane in surfactants Dawn – 7000 ppb “Alconox” – 710 ppb Ethoxylated surfactants – a known issue at FDA Ajax Dish Lemon Liquid – 1200 ppb Clairol Herbal Essences Body Envy Volumizing Shampoo – 24,000 ppb Era 2X Ultra Laundry Detergent – 14,000 ppb Tide Laundry Detergent – 55,000 ppb Healthy Times Baby's Herbal Garden Honeysuckle Baby Bath – 5300 ppb

10. Field blanks If this issue is widespread, one would expect to find an increased frequency of 1,4-dioxane in field blanks. Pulled all client sample results where the client sample name included “FB”. Results – 1204 field blanks, no hits for 1,4-dioxane above the reporting limit

11. Story #2 • Switched analysis location from one network lab to another • “Charlie – we have never seen 1,4-dioxane at this site and the location never used 1,4-dioxane, but now we have positive results for 1,4-dioxane. Could you find out if these are false positives or laboratory contamination?” • Retention time is perfect • Spectrum is perfect • Blank is clean

12. But there are some oddities

13. 8 runs later

14. Reanalysis Different instrument Soil mode with purge in VOA vial instead of water purge with standard sparge chamber All non-detects Decided it was a one time anomaly Happened again in 30 days Time for a root cause investigation!

15. The known variables • Desorb temperature • Old lab 210 C • New lab 250 C • Sparge times and flows • Identical • Sparge configuration • Old lab – water mode • New lab – both, but 1,4-dioxane only appears with water mode • Unusual detail – sulfuric acid is used as the field preservative as opposed to hydrochloric acid

16. The theory If H2SO4 somehow got into the purge gas stream and accumulated on the trap, heating could cause a dehydration reaction creating gas phase SO3 during the desorption step Methanol is used as the solvent for our internal standards and surrogates, so some methanol is always present Plausible reaction mechanism

17. Three step mechanism • Methanol reacts with sulfur trioxide forming formaldehyde and sulfur dioxide • CH3OH + SO3 CH20 + SO2 + H2O • Methanol and formaldehyde have a dehydration reaction with sulfuric acid to form acetaldehyde • CH3OH + CH2O + SO3  C2H4O + H2SO4 • Acetaldehyde does a cyclic dimerization in the acidic gas phase

19. Is there any supporting evidence?

20. How would sulfuric acid get on the trap? • Bubble ejection • Bursting bubbles create aerosols • Could carry raw sample and preservative into purge and trap system • Water purge versus soil purge • Smaller bubbles make smaller ejected droplets • Same flow through each • Water sparge vessel had 1 cm ID • VOA vial > 2 cm ID • Water sparge vertical velocity more than 4 times greater than soil vertical velocity • Droplets created in VOA vial are more likely to settle out. Larger droplets with a lower vertical velocity

21. We can test this! 5% KCl solution Sparge under different conditions into an impinger Measure chloride in impinger Calculate the amount of sample in the purge gas

22. Results Coming soon!!

23. Topic #3 Achieving Standard Reporting Limits with Reduced Sample Sizes • What determines the sensitivity of our methods • Instrument modifications to increase sensitivity • Lower Volume Initiative [LVI] • SW 846 3510C & 3520C with 250 and 125 ml sample volume • SW 846 3511 with 40 ml sample volume • QA White Paper • State Certifications • Unanticipated benefit – extraction kinetics

24. Method sensitivity • Key items are the volume of sample which the lab starts with, final volume of the extract and the volume of the extract injected onto the GC column will determine the Reporting Limits the laboratory will provide • Typical injection volumes are 1 – 2 microliters • Injection port modifications – 4 to 8 microliters • What to do with all this additional sensitivity? • Lower reporting limits • Increase final extract volume • Reduce sample size

25. LVI Standard Bottle Sizes 40 ml

26. Advantages Efficiency: Water samples can be collected at more efficient rates especially from low production groundwater wells Easier Field Logistics: Smaller bottles, less bulk to transport to sampling site Maximized Shipping Capacity: More samples will fit into a shipping container Reduced Shipping Costs: Minimized sample weight due to reduced volume Reduced Breakage: Smaller containers are much more durable

27. Approvals White paper Verified acceptability with states Demonstration packages

28. Method 3520 Heavier than water solvent boils in flask Vapor condenses in condenser and drips through sample Solvent extracts analytes as is falls through the sample Condensed solvent accumulates in bottom of extractor body and flows back into the distillation flask

29. Kinetics of extraction ΔCw = -(Vs x Cs_avg)/Vw Change in water concentration is mass removed in solvent divided by the volume of sample The volume of solvent is the distillation rate times the elapsed time, so Vs = Q x Δt The solvent concentration is the sample concentration times a partition coefficient, so Cs = Cw x k Substituting gives ΔCw = -(k xCw avg x Q x Δt) / V dC = -kCQ/V dt Rearranging and integrating gives the rate expression C/C0 = exp(-kQt/V)

30. % Extracted as a function of time at different values of k

31. % extracted over time as a function of sample size C/C0 = exp(-kQt/V)

32. The simple version Solvent to water ratio At a constant distillation rate, the solvent to water ration will increase by a factor of 4 if the sample size decreases by a factor of 4. When the sample size decreases by a factor of 4, the distillation time can decrease by a factor of 4 and we will keep the solvent to water ratio constant.

33. Results 81 analytes 6 replicates at 1000 ml for 18 hours 6 replicates at 250 ml for 4 hours

34. Implementation considerations and advantages Precedent for reduced time in 3520 – accepted by EPA and incorporated into the CLP SOW Arguably less labor with 3520, definitely better recoveries With 36 hours of extraction time, 24 hour turnaround was not possible Many laboratories maintained both procedures With 8 hours of extraction time 24 hour turnaround is possible

35. Conclusions 1,4-dioxane chemistry and optimum methods Potential field contamination that can result in false positives for 1,4-dioxane Specific laboratory conditions that can create false positives for 1,4-dioxane Reducing sample sizes and unexpected benefits