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Accurate mass analysis of hydraulic fracturing waters: Identification of polyethylene glycol surfactants by LC/Q-TOF-MS

Agilent Technologies, Inc.

June 2015

May 21, 2015 Confidentiality Label 1

W h a t i s H y d r a u l i c F r a c t u r i n g ? W h y i s i t i m p o r t a n t ?

• Thermogenic Methane

• Natural Gas & Oil

• 45,000 Wells in US

• 7500 Wells in Colorado

• Natural Gas Prices Down

• US Energy Reserves UP

• High Water Use per well

106 Gallons

• Greenhouse Gases

• Groundwater Contam

• Aesthetics

• Risks Shallow Aquifers

• Methane and HC

• Fracking Fluids

• Metals

• Radionuclides

• Salts

21 May 2015

Confidentiality Label

2

S h a l e G a s F i e l d s L o w e r 4 8 S t a t e s

Hydraulic Fracturing Production Activity Price per Wellhead

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Vengosh et al. 2014 ES&T

Hydraulic Fracturing for Natural Gas Contamination Risks

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Hydraulic Fracturing for Natural Gas Potential Risks

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LC/QTOF-MS with High Resolution and Accurate Mass In Search of “Tracers” of “Fracking” Contaminates

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• Six flowback samples from

Colorado

• Dilute 1/10, filter through

PFTE 0.1 micron

• Use slow gradient with C-8

column, 3.5 micron, 0.1%

Formic acid/ACN gradient

• High Res Q-TOF analysis

with accurate mass

– 1290 Agilent UHPLC

– 6540 Agilent Q/TOF

– 1 ppm Mass Accuracy

– 25,000 Resolving Power

Samples and Prep

Work performed by Dr. Michael Thurman, University of Colorado, Boulder

Total Ion Chromatogram Production flow-back water from Niobrara Formation

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Hydrophilic Series

Hydrophobic Series

• Series of Peaks early and late in the chromatogram

• A Hydrophilic Series and a Hydrophobic series

• Masses Differ by 44 mass units suggesting CH2-CH2-O structure for both

Fracturing Fluid Composition What is injected into the well?

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Proprietary “mixture” containing:

• Water, sand, surfactants, biocides, solvents, distillates, simple

alcohols and glycols, recycled water

Ingredient disclosure required in Colorado

Glycols -CH2-CH2-O = 44 u

Fracturing Fluid Composition Mass Difference among HPI and HPO Series (Ethoxylates?)

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Calculating Kendrick Mass Scaling Factor for [CH2-CH2-O]

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KM Scaling Factor = Isobaric Mass of CH2-CH2-O /

Accurate mass of CH2-CH2-O

KMSF = 44.0000/ 44.0265

KMSF = 0.999404559

Calculating Kendrick Mass Scaling Factor for [CH2-CH2-O]

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KM = Measured Accurate mass x KMSC

KM Defect = Nominal KM-Exact KM

Why it works: adding exactly 44.0000 mass units

to each new polymeric species, i.e. EO-5 to EO-6, etc.;

therefore, mass defect remains the same. Multiplication of

0.999404559 makes this correction for all related

compounds.

Applying the Kendrick Mass Defect to Measured Masses in HPI-Series

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Time Measured Mass Kendrick Putative Identification Exact Mass Error

(Min) (m/z) Mass (m/z) (ppm)

3.5 173.0784 172.975 PEG-EO3 Na Adduct 173.0784 0.0

4.2 217.1042 216.975 PEG-EO4 Na Adduct 217.1046 2.0

5.4 261.1304 260.975 PEG-EO5 Na Adduct 261.1309 2.0

7.3 305.1569 304.975 PEG-EO6 Na Adduct 305.1571 0.7

9.5 349.1833 348.975 PEG-EO7 Na Adduct 349.1833 0.0

10.2 393.2092 392.975 PEG-EO8 Na Adduct 393.2095 0.8

10.7 432.2802 432.023 PEG-EO9 NH4 Adduct 432.2803 0.2

11.0 476.3066 476.023 PEG-EO10 NH4 Adduct 476.3065 0.2

11.3 520.3324 520.023 PEG-EO11 NH4 Adduct 520.3328 0.8

11.5 564.3585 564.022 PEG-EO12 NH4 Adduct 564.3590 0.9

11.7 608.3856 608.023 PEG-EO13 NH4 Adduct 608.3852 0.7

11.9 652.4113 652.023 PEG-EO14 NH4 Adduct 652.4114 0.2

• Formula Generation from m/z 173.0784

• C6H14O4-Na+ ------Chem Spider Search

• Identification of PEGs

• Next test Model with MS/MS, PEG EO-6 and EO-12

MS/MS of m/z 283 (1) and MS/MS of EO-12 at m/z 564 (2) May be the EO-6 H+

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44.01267

44.01254

44.01261

44.01257

44.01256

44.01263 44.01255 CH2=CHOH

18.0110

MH+

MNH4+

MNa+

1

2

MS/MS of m/z 283 and MS/MS of EO-12 at m/z 564 May be the EO-6 H+

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Two Series of Fragmentations

• H20 and CH2=CHOH to 3 diagnostic ions

• CH2=CHOH and H20 to 3 diagnostic ions

89, 133, 177 (Ferrer et al. 2003)

O OH

C4H9O2+

Exact Mass: 89.0597

O O

OH

C6H13O3+

Exact Mass: 133.0859

O O

O

OH

C8H17O4+


O

HO

HO

O O

O

OO

HO

Chromatogram of PEG-400 Standard (Mixture)

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EO-6

EO-6 Na+

EO-6 H+

283.1751

564.3585 EO-12

Na+ H+

NH4+

PEG-EO7

PEG-EO8

PEG-EO9

NH4+

NH4+

H+

H+

Na+

Na+

OH(CH2CH2O)8H

H

C16H35O9+


OH(CH2CH2O)7H

H

C14H31O8+


OH(CH2CH2O)9H

H

C18H39O10+


Proposed Crown Ether Structure Ammonium Adduct Formation

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O

O

O

O

O

O

O

O

OHN

H

H

HH

OH

Ionic Radii

Na+ =0.102 nm, H3O+ = 0.143 nm

K + = 0.138, NH4+ = 0.145 nm

Percent Adduct Type

EO-8 PEG H+ Na+ NH4+

% % %

EO-4 4 96

EO-5 15 85

EO-6 33 66

EO-7 60 40

EO-8 40 20 40EO-9 20 20 60

EO-10 15 15 70

EO-11 6 14 80

EO-12 5 15 80

EO-13 6 14 80

EO-14 6 14 80

PEG H+ Na+ NH4+% % %

EO-4 1 99

EO-5 8 92

EO-6 20 80

EO-7 40 60

EO-8 33 33 33EO-9 20 30 50

EO-10 10 25 65

EO-11 5 25 70

EO-12 5 25 70

EO-13 5 25 70

EO-14 5 25 70

//upload.wikimedia.org/wikipedia/commons/9/9f/Atomic_&_ionic_radii.svg

NH4+ Na+

Density Functional Theory DFT Calculations by Jens Blotvogel, CSU

Table S3: Total free energies, binding constants, and atomic distances for the PEG-EO9

ammonium complex as a function of the number of interacting oxygen atoms calculated

at the IEFPCM/B3LYP/6-311G(d,p) level of theory.

No. of

interacting O

Total Free

Energy

(hartree)

Binding

Constant

log K

Min. H-O

Distance

(Å)

Avg. H-O

Distance

(Å)

Min. N-O

Distance

(Å)

Avg. N-O

Distance

(Å)

6 -1517.854737 4.5 1.86 3.44 2.85 4.18

7 -1517.856880 5.5 1.86 2.99 2.86 3.64

8 -1517.861084 7.4 1.90 2.73 2.92 3.48

9 -1517.862942 8.3 1.84 2.60 2.87 3.31

10 -1517.866147 9.7 1.84 2.44 2.87 3.14

Table S4: Total free energies, binding constants, and atomic distances for the PEG-EO9

sodium complex as a function of the number of interacting oxygen atoms calculated at

the IEFPCM/B3LYP/6-311G(d,p) level of theory.

No. of

interacting O Total Free Energy

(hartree) Binding

Constant log K Min. Na-O

Distance (Å) Avg. Na-O

Distance (Å)

6 -1623.106201 2.6 2.44 4.03

7 -1623.109024 3.9 2.46 3.54

8 -1623.109559 4.1 2.49 3.22

9 -1623.111726 5.1 2.49 3.16

10 -1623.117648 7.9 2.44 3.00

Table S5: Total free energies and binding constants for the PEG-cation complexes

calculated at the IEFPCM/B3LYP/6-311G(d,p) level of theory.

Na+ NH4

+ Δ log K

(NH4+ - Na

+)

Total Free

Energy

(hartree)

Binding

Constant log

K

Total Free

Energy

(hartree)

Binding

Constant log K

PEG EO9 -1623.117648 7.9 -

1517.866147 9.7 1.8

PEG EO8 -1469.300690 10.0 -

1364.047481 11.1 1.1

PEG EO7 -1315.483483 12.2 -

1210.227166 11.8 -0.4

This result explains why we see the PEG prefer NH4+ ion over Na+ at EO-8.

60X

NH4

Free Energy and Binding Constants

Changes in Adduct Formation

EO-20 changes to NH4+ and NH4+

OO

O

OO

O

OOO

HO

OO

O

OO

O

OO

HO

NH H

H

H

N HH

H

H

H3O+ = 0.143 nm

H+

Hydrophobic Series

Total Ion Chromatogram - Production Water

• Late Series of peaks in the chromatogram

• Masses Differ by 44 mass units suggesting CH2-CH2-O structure

• Elution reverses, more EOs the shorter the retention time

26.05 820.5996 820.111 C-12 EO-14 NH4

26.28 776.5740 776.112 C-12 EO-13 NH4 44.0256

26.49 732.5475 732.111 C-12 EO-12 NH4 44.0265

26.71 688.5215 688.112 C-12 EO-11 NH4 44.0260

26.93 644.4952 644.111 C-12 EO-10 NH4 44.0263

27.16 600.4686 600.111 C-12 EO-9 NH4 44.0266

27.40 556.4422 556.111 C-12 EO-8 NH4 44.0264

27.65 512.4160 512.111 C-12 EO-7 NH4 44.0262

27.89 468.3898 468.111 C-12 EO-6 NH4 44.0262

• Kendrick Mass Defect all equal, EO accurate mass

• Formula for m/z 468.3898 is C24H54NO7

• Chem Spider matches a C-12 ethoxylate

• MS/MS is next

MS/MS of m/z 468.3896 C-12 EO-6 NH4

468.3896

-17.0010

NH3

-168.1883

-18.0101

-44.0262

Na+ 21.9821

HO

(CH 2CH 2O )6H

N H 3C 24H 54N O 7+

Exact M ass: 468.3895

C -12 EO 6

C12H24


H+H+

H+NH4+

H+Na+

Na+Na+

NH4+NH4

+ NH4

+Na+

PEG EO17

Mass Spectrum for doubly charged PEG EO17 with mixed double adducts of Na+, NH4+,

and H+ for sample SF-1. The singly charged PEG EO17 also formed at a lesser

concentration with adducts of H+, Na+, and NH4+ (data not shown). The doubly charged

species shown here were the major ions found in the mass spectrum.

Mass Spectrum for doubly charged PEG EO17

SF-1

107

107

21 PEGs

30 PEGs

20 PEGs

GF-1

SF-2 107 EO-9

EO-9

EO-9

EO-21

Bimodal PEGs

Figure S3. Frac-t-Gram for PEG surfactants in three flowback samples.

Conclusions

PEG Composition

1. PEGs (in all 3 flowback samples)

2. Alkyl-EOs present in (2) flowback samples

3. Produced Water has PEGs

Kendrick Mass Defect

1. KMD works to find related EO’s

2. KMD finds multiply charged species

3. KMD finds mixed adducts

Acknowledgments

Tom Evans of Protreat Technologies, Denver, CO, for

Flowback Samples

Joe Weitzel and Jerry Zweigenbaum of Agilent

Technologies, Inc. for LC/QTOF-MS support

Acknowledgments