Use of Advanced Tools to Measure the Composition of

© 2018 Chevron Corporation

Use of Advanced Tools to Measure the Composition of Extractable Oxygenated Organics at a Historic Crude Oil Release

SiteRachel E. Mohler, Sungwoo Anh, Kirk O’Reilly, Dawn Zemo, Renae Magaw, Natasha Sihota,

Asheesh Tiwary, Catalina Espino Devine

8/07/2018

2© 2018 Chevron Corporation

Conceptual “TPH” plume in groundwater and natural attenuation

Dissolved organics measured as Extractable TPH (Mod ified EPA 8015)

LNAPL

Upgradient from HC plume:TPH = + Naturally occurring

organics+ Background

anthropogenic contamination

+ Lab/sampling artifacts

Dissolved HC plume:TPH = + HC (and NSOs in

case of crude oil)+ HC metabolites+ Naturally occurring




Downgradient from dissolved HC plume:TPH = + HC metabolites+ Naturally occurring




Downgradient from HC metabolite plume:TPH = + Naturally occurring




Dissolved HC plume Dissolved metabolite plume from HC biodegradation

LNAPL – Light Non Aqueous Phase LiquidsTPH – Total Petroleum Hydrocarbons

Groundwater Flow and biodegradation

HC – HydrocarbonsNSO compounds – Nitrogen, Sulphur and Oxygen containing compounds


Chromatograms Provide Insight into Presence of Non-Hydrocarbons

• Dissolved hydrocarbons will consist of compounds with carbon numbers less than 15 and will not show a UCM

• “Polars” are more soluble than hydrocarbons and compounds with carbon number greater than 15 can be in dissolved phase

Hydrocarbons “Polars”


Silica Gel Cleanup (EPA Method 3630C)

Compounds trapped depend on the solvent

Silica gel columns trap polars and allow petroleum hydrocarbons to pass through.

Surrogates allows tracking of hydrocarbons removal and retention of polars

4

TPHd – C10-C28 (µµµµg/l)

TPHd with S.G. (µµµµg/l)

% Polars

3300 810 75

220 N.D. 100

14000 13000 7

53000 2900 95

2100 340 84

2900 N.D. 100

3500 1600 54


Introduction to GCxGC

• Similar to traditional gas chromatography except that the compounds in the sample are subjected to two separations

• Simultaneous separation of analytes using two complementary (unrelated) separation mechanisms while preserving the first dimension separation

• Assume:

– GC1 can separate 5 compounds

– GC2 can separate 3 compounds

• Then:

– GC1xGC2 can separate 5 x 3, so 15 compounds!

15 20 25 30 35 40 45

0.3

0.4

0.5

0.6

Column 1 Time (seconds)

Col

umn

2 T

ime

(sec

onds

)

Alcohols

Ketones

Alkyl Benzenes

Alkanes

15 20 25 30 35 40 45

0.3

0.4

0.5

0.6

Column 1 Time (seconds)

Col

umn

2 T

ime

(sec

onds

)

Alcohols

Ketones

Alkyl Benzenes

Alkanes

Boiling Point

Pol

arity

K. J. Johnson et. al. J. Sep. Sci. (2002), 25, 297-303.


Importance of Advanced Characterization

Well DROug/l

DROwSGCug/l

Target Polars

# Tentatively Identified Polar Compounds (TIPCs) (metabolites only) in each class ( Commercial Lab GC-MS Library Search )

# Tentatively Identified Polar Compounds (TIPCs) (metabolites only) in each class ( GCxGC-MS Results )

K P Ald Alc Acid K P Ald Alc Acid

MW-3 3200 <96 All ND 0 0 0 0 9 22 0 5 19 15

MW-3 dup

2900 <120 All ND 0 0 0 0 3 14 0 4 13 14

MW-41

3300 <96 All ND 0 0 0 0 1 13 0 3 13 18

MW-26

210 <100 All ND 0 0 0 0 3 2 1 0 4 12

MW-31

470 <100 All ND 0 0 0 0 2 0 1 0 1 7

Identification is based on retention time and mass spectra, not by using standards. K= ketones, P= phenols, Ald= aldehydes, Alc= alcohols, Acids= acids and esters


Introduction to Orbitrap High Resolution Mass Spectrometry

• Molecules are directly infused into the mass spectrometer

• Molecules are ionized and separated based on their mass to charge ratio (m/z)

– Negative mode: acidic species

– Positive Mode: basic species

– Non-polar molecules will not be detected

• The mass spectrometer provides molecular formulas but cannot differentiate isomers


High Resolution Mass Spectrum using ESI in Negative Mode

ltq6731_8515994A neg #1 RT: 0.00 AV: 1 NL: 9.34E3T: FTMS - p ESI Full ms [150.00-1200.00]

150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900m/z

0

5

10

15

20

25

30

35

40

45

50

55

60

65

70

75

80

85

90

95

100

Rel

ativ

e A

bund

ance

475.25

531.28

443.19565.26

551.24455.19

429.17 577.26

591.27

607.31

619.31

211.11 279.14

645.29

373.18

657.29

683.36

191.05699.30345.15

m/z

Rel

ativ

e A

bund

ance

475.25

C30H35O5-


Crude Oil Site


Analytical Approach

Five Groundwater Samples (one upgradient, two within hydrocarbon plume, one within hydrocarbon footprint and one downgradient)

DCM extraction (nSG)

DCM extraction (SG)

Methanol EluateDCM extraction (8270)

1) EPA TPH method 8015

2) GCxGC-TOFMS

3) Orbitrap

1) Quantitative EPA method 8270

2) GCxGC-TOFMS

1) EPA TPH method 8015

2) GCxGC-TOFMS

1) GCxGC-TOFMS

Two LNAPL samples were also collected and analyzed on the Orbitrap


Composition of Organics Becomes more Like Background in the Downgradient Wells

UDF

DHDH

D


GCxGC Groundwater Results


Tentatively Identified Compounds Identified by GCxGC-TOFMS

• 2016 Bemidji data set contains 178 unique TICs of which 158 (89%) are in our fuels database

1(3H) Isobenzofuranone, 3,3 dimethyl

O

1 (2H) Naphthalenone, 3,4 dihydro

2,3,4 trimethyl, hex-3-enal

O

O

α methyl benzenealdehyde

HO

1-methyl, 1-indanol

2,6 dimethyl, 2 octanol

OH

2,3 dimethyl phenol

OH

O

OOctanoic acid, methyl ester

O

O


DH

Orbitrap Carbon Number Distribution is Different Based on location within the Plume

C33C33

C40C28

U DF

DH

C40

C28

D

C14


Compounds with 4-7 Oxygens DominateESI Negative Ion Mode

0.0

21.6

7.6

17.5

9.9

15.015.0

9.3

4.10.0

O1 O2 O3 O4 O5 O6 O7 O8 O9 O10

310E-U

1.0 1.4 3.0

10.9

28.229.0

18.1

8.52.7 2.7

O1 O2 O3 O4 O5 O6 O7 O8 O9 O10

9315B-DH

5.53.7

8.212.4

21.223.8

15.1

6.3

1.0 2.8

O1 O2 O3 O4 O5 O6 O7 O8 O9 O10

518A-DH

0.0 0.5 1.5

19.524.5

18.514.1

10.16.3

3.7 1.4

533C-DF

0.0 0.6 0.4

17.5

22.820.7

16.1

10.77.6

3.6

O1 O2 O3 O4 O5 O6 O7 O8 O9 O10

1217E-D


Oxygen containing organics vary across the site

518A-DH 9315B-DH 1217E-D533C-DF310E-U


Acids profile in LNAPL is much different from what is present in the groundwater

Appears to be a mixture of paraffinic and mononaphthenic carboxylic acids based on DBE

Appears to be mainly paraffinic dicarboxylic acids based on DBE

421B 533A


Summary

• TPH is a complex mixture of organic compounds

– Metabolite compounds found at Bemidji have been found at fuel release sites.

• Advanced characterization tools indicate

– Composition of oxygen containing compounds in groundwater at historic crude oil release site are similar to fuel releases (GCxGC-TOFMS)

– Solvents can extract oxygen containing compounds with carbon numbers up to C50 (Orbitrap)

– Oxygen containing compounds downgradient can have very few similarities to hydrocarbons that were part of the original release (Orbitrap)


Acknowledgements

• Chevron Environmental Management Company:

– Project managers

– Funding

• Analytical Support

– Matthew Hurt

– Jeff Curtis

• USGS, Beltrami County and the Minnesota Pollution Control Agency for access to the Bemidji site

• Barbara Bekins, Jared Trost, and Andrew Berg of the USGS for site background information and field support

Documents

Use of Advanced Tools to Measure the Composition of