Optimization of 1,4-Dioxane and Ethanol Detection Anne Jurek – Applications Chemist

Overview Who is EST analytical? Typical Ethanol and 1,4-Dioxane Issues Experimental parameters examined Observations Conclusions Q&A

Introduction to EST Analytical Purge & Trap Experts Privately held Founded in 1990 Environmental roots Full Support and Service PURGE & TRAP

Purge & Trap Products

Ethanol and 1,4-Dioxane Problems Compounds are miscible in water and difficult to purge out. Compounds are difficult to clean up after a sample is run, blank contamination Recovery issues when running a calibration standard

Ethanol and 1,4-Dioxane Problem Source Identify Problem Source: EST Analytical researched ethanol and 1,4-dioxane problems and found that the main source is the fact that ethanol and 1,4-dioxane like to hang on to the sparge tube and the frit therein.

Rxi-624Sil MS 30m x 0.25mm I.D. 1.4µm film thickness GC/MS Parameters GC/MS Agilent 7890A/5975C inert XL Inlet Split/Splitless Inlet Temp. 220ºC Inlet Head Pressure 12.153 psi Mode Split Split Ratio 40:01:00 Column Rxi-624Sil MS 30m x 0.25mm I.D. 1.4µm film thickness Oven Temp. Program 45ºC hold for 1 min, ramp 15ºC/min to 220ºC, hold for 1.33 min, 14 min run time Column Flow Rate 1mL/min Gas Helium Total Flow 44mL/min Source Temp. 230ºC Quad Temp. 150ºC MS Transfer Line Temp. 180ºC Scan Range m/z 35-300 Scans 5.2 scans/sec SIM Ions (0.7min to 3.49min) 45, 46 SIM Ions (3.5min to 14min) 58, 88 Solvent Delay 0.7 min

Purge and Trap Starting Parameters Purge and Trap Concentrator EST Encon Evolution Trap Type Vocarb 3000 Valve Oven Temp. 150ºC Transfer Line Temp. Trap Temp. 35ºC Moisture Reduction Trap (MoRT) Temp. 39ºC Purge Time 11 min Purge Flow 40mL/min Purge Temp. Tested Parameter Dry Purge Temp. ambient Dry Purge Flow Dry Purge Time 1.0 min Desorb Pressure Control On Desorb Pressure 5psi Desorb Time 0.5 min Desorb Preheat Delay 10 sec Desorb Temp. 250ºC Moisture Reduction Trap (MoRT) Bake Temp. 210ºC Bake Temp 260ºC Sparge Vessel Bake Temp. Bake Time 6 Bake Flow 85mL/min Purge and Trap Auto-Sampler EST Centurion WS Sample Type Water Water Volume 5ml Extraction Internal Standard Vol. 5 µl

Parameters Tested Altered Parameters Baseline Parameters A Iteration B Iteration C Iteration D Iteration E Iteration F Iteration G Sparge Vessel Type 5ml Fritted 40ml Vial, 10ml purge volume 5ml Fritless Bulbless Purge Temperature (ºC) Room Temp. 40 60 Sparge Bake Temperature (ºC) 110 Not Applied Not Applied* *For Iteration E, the patented Water Prep-Mode was used.

Traditional Sparge Vessel

Fritless Bulbless Sparge Vessel

Water Prep Mode Patented feature of the Centurion Runs all samples in the soil station of the Centurion Requires a syringe option Transfers water samples into a separate vial in the soil station without exposing the sample to atmosphere, thus providing fresh “glassware” for each sample

Water Prep Mode Step 1 Empty vials are placed in one tray while water standards or samples are placed in the second tray. The system transports the empty vial to the soil sampling station and it is moved onto the sample needle

Water Prep Mode Step 2 The arm moves over to the full water vial, the vial is pressurized with helium gas and the prescribed water volume is removed. Internal standard (IS) is added by injecting IS into the sample as it is transported to the vial in the soil sampling station.

Water Prep Mode Step 3 The sample is heated and purged in the same manner as a soil sample, and the analytes are trapped on the analytical trap. Next, the analytes are desorbed onto the GC column.

To Make an 8260 Standard at 200ppm Diluted in P&T Methanol Standard Preparation To Make an 8260 Standard at 200ppm Diluted in P&T Methanol Amount Restek Part # Standard Concentration Final Vol. 200µl 30466 Ethanol 10.0mg/ml 2.0ml 30265 2-Cleve 2.0mg/ml 30633 Cal Mix #1 30042 502.2 Cal Mix #1 30489 Acetates 30465 Cal Oxy 2.0-10.0mg/ml 30287 1,4-Dioxane 160µl 30073 Surr. Mix 2.5mg/ml 80µl 30006 VOA Cal Mix #1 5.0mg/ml Use 2ml volumetric flask and dilute standards to 2.0ml in purge and trap methanol To Make a 10x Dilution of the 8260 Standard (From 200ppm to 20ppm) Diluted in P&T Methanol 200µl of 200ppm standard diluted to 2.0ml in purge and trap methanol

Prepared an 8260 Curve Diluted in De-ionized/UV Treated Water Curve Preparation Prepared an 8260 Curve Diluted in De-ionized/UV Treated Water Concentration Standard Standard Amount Final Vol. 0.5ppb 20ppm 2.5µl 100ml 1ppb 5µl 2ppb 10µl 5ppb 25µl 10ppb 50µl 20ppb 200ppm 50ppb 100ppb 200ppb 100µl Water Standards Fill 40ml Vial with final standard leaving no headspace in the vial.

Curve Average RF Curve Average Response Factors Compound Baseline--RT purge, 110ºC Sparge Bake 40ºC Purge, 110ºC Sparge Bake 60ºC Purge, 110ºC Sparge Bake 40ºC Purge, No Sparge Bake Water Extraction 40ºC Purge 40ºC Purge, 110ºC Sparge Bake, Fritless Bulbless Sparger 40ºC Purge, NoSparge Bake, Fritless Bulbless Sparger Ethanol 0.002 0.004 0.011 0.008 0.012 0.009 0.015 1,4-Dioxane 0.003 0.010 0.013

Curve Linearity Curve Linearity Compound Baseline--RT purge, 110ºC Sparge Bake 40ºC Purge, 110ºC Sparge Bake 60ºC Purge, 110ºC Sparge Bake 40ºC Purge, No Sparge Bake Water Extraction 40ºC Purge 40ºC Purge, 110ºC Sparge Bake, Fritless Bulbless Sparger 40ºC Purge, NoSparge Bake, Fritless Bulbless Sparger Ethanol 0.997* 14.520 10.600 11.540 0.999* 14.710 10.200 1,4-Dioxane 0.998* 13.810 14.840 12.290 7.470 13.720 7.160 *Indicates linear regression

Precision Results at 50ppb Precision at 50ppb (%RSD) Compound Parameter Iteration A B C D E F G Ethanol 13.43 7.29 12.48 2.47 2.54 6.18 3.68 1,4-Dioxane 9.44 7.64 14.86 2.10 4.34 7.20 2.51

Percent Recovery at 50ppb Compound Parameter Iteration   A B C D E F G Ethanol 170.24 108.45 125.90 110.68 93.71 80.05 96.53 1,4-Dioxane 148.44 128.01 122.49 110.95 101.55 80.27 97.45

Ethanol and 1,4-Dioxane Carryover Graphic

Ethanol and 1,4-Dioxane Carryover Table Average Carryover after 50ppb Compound Iteration A B C D E F G Ethanol 63ppb 76ppb 38ppb 58ppb ND 1,4-Dioxane 53ppb 60ppb 52ppb 44ppb 1,2,4-Trichlorobenzene 0.50ppb 0.53ppb Naphthalene 0.59ppb 0.61ppb 1,2,3-Trichlorobenzene 0.57ppb ND signifies Non Detect

50ppb Chromatogram

Curve Linearity and RF Table Compound Water Extraction 40ºC Purge   Fritless Bulbless Sparge Vessel, 40ºC purge, Sparge Bake Curve Linearity Response Factor Dichlorodifluoromethane 3.30 0.543 7.73 0.420 Chloromethane 11.39 1.016 12.68 0.963 Vinyl Chloride 2.08 0.927 5.31 0.889 Bromomethane 11.04 0.547 14.45 0.568 Chloroethane 11.48 0.613 12.83 0.623 Ethanol 0.999* 0.012 14.71 0.009 Trichlorofluoromethane 3.86 0.614 7.91 0.540 1,1-Dichloroethene 4.26 0.611 6.46 0.517 Acetone 13.93 0.346 13.09 0.392 Carbon Disulfide 5.64 2.112 7.28 1.544 Methylene Chloride 13.51 0.786 9.99 0.728 MTBE 3.38 2.113 2.39 2.174 1,1-Dichloroethane 5.99 1.419 8.15 1.245 2-Butanone 5.86 1.574 9.97 1.901 Chloroform 10.60 1.330 5.51 1.211 Benzene 2.89 3.079 2.23 2.735 1,2-Dichloropropane 0.458 4.85 0.410 1,4-Dioxane 7.47 0.010 13.72 Toluene 12.28 1.136 4.15 0.958 2-Hexanone 6.69 0.367 5.14 0.448 Chlorobenzene 6.08 1.340 2.93 1.156 Ethylbenzene 7.62 2.321 6.16 1.994 Xylene (m+p) 7.87 1.804 5.89 1.527 Xylene (o) 7.56 1.819 5.6 1.614 Bromoform 0.259 13.74 0.286 1,1,2,2-Tetrachloroethane 6.15 1.266 4.33 1.213 1,2-Dibromo-3-chloropropane 7.97 0.245 4.89 0.271 1,2,4-Trichlorobenzene 7.68 1.291 5.61 1.020 Naphthalene 12.46 3.787 5.1 3.365 Hexachlorobutadiene 9.30 0.556 7.86 0.376 1,2,3-Trichlorobenzene 12.74 1.253 5.08 0.955

Precision and Accuracy Table Compound Water Extraction 40ºC Purge   Fritless Bulbless Sparge Vessel, 40ºC purge, Sparge Bake Precision (%RSD) % Recovery Dichlorodifluoromethane 5.03 96.45 6.62 100.91 Chloromethane 3.71 90.88 4.44 87.32 Vinyl Chloride 4.72 97.24 5.13 95.08 Bromomethane 3.20 89.98 5.25 90.29 Chloroethane 4.18 90.66 4.76 87.49 Ethanol 2.54 93.71 6.18 80.05 Trichlorofluoromethane 4.80 98.25 6.45 98.41 1,1-Dichloroethene 3.99 98.96 5.73 101.07 Acetone 3.30 93.93 3.06 89.45 Carbon Disulfide 4.27 98.19 5.49 100.13 Methylene Chloride 2.12 91.85 2.31 92.19 MTBE 1.55 100.14 1.72 104.56 1,1-Dichloroethane 2.97 100.83 3.67 106.21 2-Butanone 1.21 93.14 4.7 95.12 Chloroform 2.60 92.31 99.47 Benzene 2.92 97.77 3.8 100.65 1,2-Dichloropropane 2.46 99.63 3.17 105.24 1,4-Dioxane 4.34 101.55 7.2 80.27 Toluene 3.50 92.80 4.79 102.29 2-Hexanone 1.64 98.85 1.81 106.37 Chlorobenzene 2.19 97.14 3.1 97.02 Ethylbenzene 3.45 98.97 Xylene (m+p) 3.18 97.64 4.06 98.29 Xylene (o) 2.45 99.50 3.62 98.74 Bromoform 1.52 116.43 1.42 109.97 1,1,2,2-Tetrachloroethane 1.09 94.79 2.06 100.72 1,2-Dibromo-3-chloropropane 0.91 104.86 1.19 104.47 1,2,4-Trichlorobenzene 98.69 2.71 98.64 Naphthalene 95.10 1.63 101.97 Hexachlorobutadiene 4.49 97.58 5.07 96.15 1,2,3-Trichlorobenzene 93.05 99.03

Conclusions The carryover of the 1,4-Dioxane and Ethanol proved to be the main problem with precision and accuracy of standards over time. The traditional sparge vessel with the frit and bulb was the most troublesome for analyte carryover. The fritless/bulbless sparge vessel showed a marked improvement in the precision and accuracy of the results.

Conclusions The fritless/bulbless sparge vessel also displayed much less carryover than the traditional sparge vessel. Heating the fritless/bulbless sparge vessel would be the recommendation for testing a full 8260 compound list due to the carryover of the heavier compounds is limited with this feature.

Conclusions A new “sparge” vessel proved to be the optimum option for this analysis. Automated water extraction provided a new 40ml vial for purging each sample thus there was no carryover because samples were purged in a disposable vial. Water extraction also provided excellent linearity and compound response for the analytes of interest.

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