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

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

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

4. Purge & Trap Products

5. 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

6. 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.

7. 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
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
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

8. 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

9. 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.

10. Traditional Sparge Vessel

11. Fritless Bulbless Sparge Vessel

12. 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

13. 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

14. 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.

15. 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.

17. 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
mg/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

18. 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.

19. 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

20. 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

21. 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

22. 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

23. Ethanol and 1,4-Dioxane Carryover Graphic

24. 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

25. 50ppb Chromatogram

26. 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

27. 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

28. 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.

29. 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.

30. 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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