Total Petroleum Hydrocarbon Criteria Working Group Series Volume 1 Analysis of Petroleum Hydrocarbons in Environmental Media

8/10/2019 Total Petroleum Hydrocarbon Criteria Working Group Series Volume 1 Analysis of Petroleum Hydrocarbons in Envir

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Analysis of Pet roleumHydrocarbons inEnvironmental Media

Total Pet roleum Hydrocarbon Crit eria Work ing Group Series

Volume 1


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These organizations sponsored or contributed to thecompletion of this t echnical document, prepared bythe TPH Criteria Working Group:

American Petroleum Institute

Association for the Environmental Health of Soils

Association of American Railroads

British Petroleum

Chevron Research and Technology Company

Exxon Biomedical Sciences, Inc.

Retec, Inc.

Shell Development Company

United States Air Force, Air Force Research Laboratory

University of Massachusetts


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March 199 8


Total Pet roleum Hydrocarbon Cri teria Work ing Group Series

Volume 1

SPONSORED BY:

Association of American Railroads

BP Oil Company

United States Air Force, ArmstrongLaboratory, Occupational MedicineDivision

EDITED BY:

Wade WeismanAir Force Research Laboratory,

Operational Toxicology Branch


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Amherst Scient i f ic Publ ishers

150 Fearing StreetAmherst, Massachusetts 01002

1998 by Am hers t Sc ie nt if ic Publi sh ers . Al l ri gh t s re served.

ISBN 1-884-940-14-5

The material contained in this document was obtained from independent and highly respected sources.Every attempt has been made to ensure accurate, reliable information, however, the publisher cannot beheld responsible for the information or how the information is applied. Opinions expressed in this book arethose of the Total Petroleum Hydrocarbon Criteria Working Group and do not reflect those of the publisher.

This document was prepared by the Total Petroleum Hydrocarbon Criteria Working Group. Neither theWorking Group nor members of the Working Group:

a. Makes any warranty or representation, expressed or implied, with respect to the accuracy, com-pleteness, or usefulness of the information contained in this report, or that the use of any appa-ratus, method, or process disclosed in this report may not infringe privately owned rights; or

b. Assumes any liability with respect to the use of, or for damages resulting from the use of,any information, apparatus, method, or process disclosed in this report.

This document may be reproduced only in its entirety for unlimited distribution. Every reasonable efforthas been made to give reliable data and information, but neither the TPH Criteria Working Group nor thecontributing individuals or their companies assume any responsibility for the validity of all materials or forthe consequences of their use or misuse.

A portion of the proceeds from the sale of this book will be donated to the Plant-a-Tree Program, a refor-estation program managed by the U.S. Forest Service.

Printed in the United States of America


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CONTENTS

PREFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix

ACKNOWLEDGMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi

1. PURPOSE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

3. OVERVIEW OF TPH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

3.1 Risk Implications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

4. UNDERSTANDING THE PETROLEUM ANALYTICAL PROCESS:FROM SAMPLE COLLECTION TO MEASUREMENT . . . . . . . . . . . . . . . . . . . . . . . 6

4.1 Collection And Preservation Of Environmental Samples . . . . . . . . . . . . . . 7

4.2 Sample Extraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

Water Samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Soil Sample s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Free Phase Hydrocarbon Samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

4.3 Concentrat ion of Sample Extract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

4.4 Cleanup of Sample Extract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

4.5 M easurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Total Petroleum Hydrocarbon (TPH) Measurement . . . . . . . . . . . . . . . . . 18

Petroleum Group Type Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Petroleum Const i tuent Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . 18

5. TOTAL PETROLEUM HYDROCARBON (TPH) MEASUREMENT:DETAILED REVIEW OF SELECTED ANALYTICAL METHODS . . . . . . . . . . . . . . . . . 18

5.1 Gas Chromat ography (GC) TPH Met hods . . . . . . . . . . . . . . . . . . . . . . . . 19

Overview of the Technique . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Example Met hods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

What Do GC Met hods Measure? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Interf erences/Limitat ions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

5.2 Infrared Spectroscopy (IR) TPH Met hods . . . . . . . . . . . . . . . . . . . . . . . . 27


Example Met hods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

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What Do IR Met hods Measure? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30


5.3 Gravimet ric TPH Met hods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31


Example Met hods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

What Do Gravimetric Me thods M easure? . . . . . . . . . . . . . . . . . . . . . . . . 32


5.4 Imm unoassay TPH Met hods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33


Example Met hods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

What Do Immunoassay Methods M easure? . . . . . . . . . . . . . . . . . . . . . . 34


6. PETROLEUM GROUP TYPE MEASUREMENT: DETAILED REVIEWOF SELECTED ANALYTICAL METHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

6.1 Thin Layer Chromat ography (TLC) Group Type Met hods . . . . . . . . . . . . . . 34


Example Met hods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

What Do TLC Met hods Measure? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 5


6.2 Im munoassay Group Type Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37Overview of the Technique . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Example Met hods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

What Do Immunoassay Methods M easure? . . . . . . . . . . . . . . . . . . . . . . 37


7. INDIVIDUAL PETROLEUM CONSTITUENT MEASUREMENT:DETAILED REVIEW OF SELECTED ANALYTICAL METHODS . . . . . . . . . . . . . . . . . 38

7.1 Gas Chromatography with Photoionization Det ection(GC/PID) Petroleum Constit uent M ethods . . . . . . . . . . . . . . . . . . . . . . . . 41

Overview of Techniq ue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Example Met hods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

What Do GC/PID Methods M easure? . . . . . . . . . . . . . . . . . . . . . . . . . . . 41


7.2 Gas Chromatography With Flame Ionization Detect ion(GC/FID) Petroleum Constit uent M ethods . . . . . . . . . . . . . . . . . . . . . . . . 42

Overview of Techniq ue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

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Example Met hods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

What Do GC/FID Methods M easure? . . . . . . . . . . . . . . . . . . . . . . . . . . . 43


7.3 High Performance Liquid Chromatography (HPLC) Petroleum

Constit uent M ethods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43Overview of Techniqu e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Example Met hods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

What Do HPLC Methods Measure? . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44


7.4 Gas Chromatography With Mass Spectrometry Detection(GC/MS) Petroleum Constit uent M ethods . . . . . . . . . . . . . . . . . . . . . . . . 45

Overview of Techniqu e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Example Met hods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

What Do GC/MS Methods M easure? . . . . . . . . . . . . . . . . . . . . . . . . . . . 47


8 . EVOLVING METHODS FOR PETROLEUM HYDROCARBON FRACTIONS . . . . . . . . . 48

8.1 What Do Petroleum Fract ion Methods Measure? . . . . . . . . . . . . . . . . . . 48

8.2 Why Use Petroleum Fraction Me thods? . . . . . . . . . . . . . . . . . . . . . . . . . 48

8.3 Examples Of Petroleum Fraction Me thods . . . . . . . . . . . . . . . . . . . . . . . 49

TPHCWG Analytical Met hod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Massachuset ts EPH/VPH Met hod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Appendi x I - HYDROCARBON CHEMISTRY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Appen dix II - CHARACTERIZATION OF PETROLEUM PRODUCTS . . . . . . . . . . . . . . . 59

Appendi x II-A: PRODUCT COMPOSITION AND SPECIFICATION . . . . . . . . . . . . . . . . 61

Appe nd ix II-B: ENVIRONMENTAL FATE OF PETROLEUM PRODUCTS:WEATHERING AND TRANSPORT . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Appendix III - Refinery Flow Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

Appendix IV - Quick Reference of TPH Met hods . . . . . . . . . . . . . . . . . . . . . . . . . 81

EXPLANATION OF ACRONYMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

GLOSSARY OF TERMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

BIBLIOGRAPHY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

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PREFACE

This documen t is the first in a series from the Tota l Petro leum H ydro carbo n

Criteria Working G roup (TPH CWG , or Working G roup) . The Working G roup

convened in 1993 to address the large disparity among cleanup requirements

being used by states at sites con taminated with h ydro carbo n m aterials such a s fuels,

lubricating oils and crude oils. These requirements usually focus on total petrole-

um hydrocarbon (TPH), with numerical standards ranging from tens to tens of

thousands of milligrams of TPH per kilogram of soil. Recognizing that these stan-

da rds are n ot based on a scientific assessment of human hea lth risk, Working

G roup m embers established the fo llowing goal fo r th eir effort:

To develop scienti fi cal ly defensible information for establishing soi l cleanup levels that

are protecti ve of human health at petroleum contaminated sites.

The Working G roup is guided by a steering com mittee con sisting o f representa-

tives from industry, government, and academia. Some of the active participants

among the more than 400 involved include the Gas Research Institute, several

major petroleum companies including Chevron, Exxon, British Petroleum and

Shell, the American Petroleum Institute, the Association of American Railroads,

several state governments (Washington, Texas, Colorad o, H awaii, Louisian a, New

Mexico, Massachusetts), the U.S. Environmental Protection Agency, the

Department of Defense, the University of Massachusetts, and private consulting

firms includin g EA Engineering, Science & Techn ology and Menzie-Cura &

Associates, Inc.

The Working G roup compiled th eir data collection an d a na lytical efforts into

five volumes:

Volume 1. Analysis of Petroleum Hydrocarbons in Envi ronmental Media (this

volume) discusses an d critiques analytical method s for q uan tifying

TPH, petroleum mixtures and individual petroleum constituents

in soil and water samples. It is designed to be a reference tool for

the nonchemist, describing what information analytical methods

can provide for risk assessment.

Volu me 2. Composi ti on of Petroleum Mixtures (in press) provides the best

available composition information for a variety of petroleum

products.

Volume 3. Selecti on of Representati ve Total Petroleum Hydrocarbon (TPH) Fracti ons

Based on Fate and Transport Considerat ions(1997, Amherst Scientific

Publishers) defines fractions of TPH expected to behave similarly

in the environment. Identification of these fractions simplifies

analysis of environmental samples, fate and transport modeling,

an d risk assessment efforts at petro leum con taminated sites.

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Volume 4. Development of Fraction-Specif ic Reference Doses (RfDs) and Reference

Concentrati ons (RfCs) for Total Petroleum Hydrocarbons (TPH)(1997,

Amherst Scientific Pub lishers) provides the techn ical basis for the

development o f TPH fraction -specific RfDs and RfC s for use in the

ha zard assessmen t step o f th e Wor king G roups risk-ba sed

appro ach to establishing soil cleanup levels at pet roleum conta mi-nated sites.

Volume 5. Human H ealth Ri sk-Based Evaluati on Of Petroleum Contaminated Sites:

Implementat ion Of The Worki ng Group Approach.(in press). This docu-

ment integrates the findings of Volumes 1 through 4 into a risk-

based framework for development of cleanup goals at petroleum

contaminated sites. It includes descriptions of demonstration sites

where th e Working G roup approach ha s been used successfully.

Amherst Scientific Publishers will publish these volumes in 1997 and 1998. In

ad dition to these volumes, results of projects where use o f th e Working G roup

approach has been demonstrated (demonstration sites) and a concise technicalsummary document are now or will soon be available on the U.S. Air Force

Toxico logy Division web site (h ttp://voyager.wpafb .af .mil). At this web site,

Working G roup publications may be downloaded from th e recent pub lications

icon. Add itional Working G roup resources will be ad ded to this web site as they

become available.

We hope you find these documents to be useful in your effort to evaluate and

determ ine acceptable risk-based cleanup criteria at petroleum conta mina ted sites.

Wade H . Weisma n

Ch airman, TPH Criteria Working G roup

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ACKNOWLEDGMENTS

The TPH Criteria Working G roup would like to especially tha nk BP Oil for their

stron g support o f this effort th rough permitting the use of th e TPH in Soil Primer,

developed by Elaine Schwerko for BP Oil, Environmen tal Techno logy Branch,

September, 1993. The d evelopment a nd prod uction o f this document was sup-

ported, in part, through the financial contribution of the Association of American

Railroads (AAR). The continued support of TPH Working G roup effo rts by Dr.

Christopher Barkan of the Environmental and Hazardous Materials Research

Pro gram of th e AAR Research an d Test Depa rtmen t is grea tly appreciated .Additionally, the following persons and organizations contributed significant

amo unts of in-kind support toward the completion of th is document :

Beth Albertson Friedman & Bruya, Inc.

John Fitzgerald Massachusetts Department of

Environmental Protection

Elizabeth A. Harvey, Chevron Research and Technology

John Fetzer

G . Cornell Long U nited States Air Force,

Armstrong Labora tory

Ileana Rhodes Shell Development Company

G eorge Sawyer Mobil Oil Corporation

Wade Weisman Air Force Research Laboratory,

Operation al Toxicology Bran ch

Donna J. Vorhees, Menzie-Cura & Associa tes, Inc.

Chris M. Long

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1. PURPOSE

The chem ical composition of petro leum prod ucts is complex an d ma y chan ge over

time following release into the environment. These factors make it difficult to

select the most appropriate analytical methods for evaluating environmental

samples. The Total P etroleum H ydrocarb on C riteria Working G roup ( theWorking G roup ) prepared this volume to assist site man agers, risk assessors, reg-

ulators and others who may not have expertise in analytical chemistry in under-

standing the complexities of petroleum hydrocarbon characterization. This

volume describes petroleum an alytical methods and what they can an d can not tell

you about environmental media (e.g., soil, groundwater, and surface water) at

petroleum contaminated sites. The information provided in this volume will help

the reader to accurately interpret results from petroleum analytical methods. This

volume is not meant to be a comprehensive text on analytical methods and does

not recomm end o r man date an y particular method. The goa l of the Working

Group is to provide the technical information needed by regulators, risk assessors,

an d site manag ers to implemen t health r isk-based d ecisions at petroleum con tam-

inated sites.

2. INTRODUCTION

There are a significant number of petroleum hydrocarbon impacted sites across

the U nited States resulting from a wide ra nge o f past industrial, military, an d petro-

leum production, and distribution practices. D ifficulties in evaluating an d remedi-

ating these sites arise from the complexity of the regulatory, scientific, and eco-

nomic issues regarding impacted soil and water. Most investigations involving

petroleum hydrocarbons are regulated by the states with different req uirements in

methodologies, action levels, and cleanup criteria. The chemical composition of

petroleum products is complex and varied and changes over time and distance

when released to the en vironm ent. These factors make it difficult to select the mo st

appropriate an alytical test meth ods for evaluating environmental samples and toaccurately interpret and use the d ata.

The Working G roup d eveloped th is volume to provide summar y info rma tion

about an alytical techniq ues and method s for total petroleum hydrocarbons (TPH ),

petroleum by chemical class and boiling point ranges, and individual petroleum

con stituents. Newer fraction -based an alytical approa ches also are discussed.

Discussion centers on analytical methods for soil, sediment, and water because

most published methods measure TPH in these media. However, much of the dis-

cussion in this volume is relevant to other environmental media, such as air.

Analytical methods for media such a s sediment a nd air are o ften mo dified versions

of established methods for soil and water.

This volume is organized into the following principal sections:

Section 3: Overview of TPHThis section provides an overview of the historical measurement and use of

TPH data.

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Section 4: Understanding T he Petroleum Analytical Process: From Sample Collecti on

To Measurement

This section provides a gen eral o verview of th e an alytical process characteris-

tics that a re common to most method s for quan tifying TPH , individual petro-

leum constituents, a nd petroleum fractions.

Section 5: Total Petroleum Hydrocarbon (TPH) M easurement: Detai led Review Of

Selected Analytical Methods

This section d escribes ana lytical metho ds for TPH tha t are based on four ma in

analytical techniques: gas chromatography, infrared spectrometry, gravimetry,

and immunoassay measurements.

Section 6: Petroleum Group Type Measurement: Detai led Revi ew Of Selected

Analytical Methods

This section d escribes analytical metho ds for petroleum group s that are b ased

on two ma in ana lytical techniq ues: thin layer chromatograph y and immun oas-

say measurements. Petroleum groups include different categories of hydro-

carbons such as saturates, aromatics, and polars/resins.

Section 7: Indivi dual Petroleum Consti tuent Measurement: Detai led Review of SelectedAnalyti cal Methods

This section describes analytical methods for individual petroleum con-

stituents that a re based on four main analytical techniques: gas chromatogra-

phy with photoionization detection, gas chromatography with flame ioniza-

tion detection, high performance liquid chromatography, and gas chro-

matography with mass spectrometry detection. Individual petroleum con-

stituents often include benzene, carcinogenic polycyclic aromatic hydrocar-

bons, and other compo unds common ly associated with petroleum.

Section 8: Evolving M ethods For Petroleum Hydrocarbon Fractions

This section provides an introduction to several newer analytical methods for

quantifying petroleum fractions rather than TPH, groups or individual con-

stituents. It explains why such methods are being developed for evaluatinghuman health risk at petroleum con taminated sites.

3. OVERVIEW OF TPH

This section presents a historical perspective on the use of TPH in evaluating petro-

leum con taminated sites. Techn ical terms used in this section a re explained in

greater detail in subsequent sections. The use of TPH concentrations to establish

target cleanup levels for soil or water is a commo n a pproach implemented by regu-

lator y agencies in th e U nited States. Approximately 75% of the states use TPH -based

cleanup criteria. Because these values have become such key remediation criteria, it

is essentia l that everyone using TPH da ta - environmenta l coord inato rs, field per-

sonnel, and regulators - be knowledgeable abo ut the various analytical metho ds. It isimportant to know that minor method deviations may be found from state to state.

TPH is sometimes referred to as mineral oil, hydrocarbon oil, extractable hydro-

carbon, and oil and grease. There are many analytical techniques available that

measure TPH concentrations in th e environment. No single method measures the

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entire ran ge of petroleum -derived hydrocar bon s .Becau se the techn iques var y in

the way hydrocarbo ns are extracted, cleaned up, and detected, they each measure

slightly differen t subsets of th e petroleum-derived hydroca rbon s present in a

sample. See Section 4. The definition of TPH depends on the analytical method

used because the TPH measurement is the total concentration of the h ydrocarbo ns

extracted and measured b y a particular method . The same sample analyzed by dif-

ferent TPH methods may produce different TPH values. For this reason, it is

important to know exactly how each d etermination is made. In terpretation o f the

results depends on understanding the capabilities and limitations of the selected

method . If used indiscriminately, TPH data can be m isleading an d could lead to a n

inaccura te a ssessmen t o f risk.

There are several reasons why TPH data do not provide ideal information for

investigating sites and establishing target cleanup criteria. For example, use of the

term TPH suggests that the a nalytical method measures the combined concentra-

tion of all petroleum-derived hydrocarb ons, thereby giving an a ccurate ind ication

of site contamination. But this is not always the case. Furthermore, target cleanup

levels based on TPH concentrations implicitly assume (1) the TPH result is an

accurate measurement of petroleum-derived h ydrocarbo n con centration, an d (2)the TPH result indica tes the level of risk associated with the conta mina tion. These

assumptions are not correct due to many factors including the nonspecificity of

some of the methods used and, the complex nature of petroleum hydrocarbons

and their interaction with th e environment o ver time.

One significant difficulty in measuring TPH for different product types is the

fact that the boiling ranges and carbo n numb er ranges of refined petroleum prod-

ucts often overlap. Refined petroleum products are primarily manufactured

through distillation processes that separate fractions from crude oil by their boiling

ran ges. See Append ix III Refiner y Flow Diagra ms. Manufactu ring pro cesses may

also increase the yield of low molecular weight fractions, reduce the concentration

of undesirable sulfur and nitrogen components, and incorporate performance

enhancing additives. Additionally, because it is impossible to identify all con-

stituents of a petroleum product, these constituents are often described by theirboiling point ran ges. Because distillations are no t capable of producing sharp d is-

tinctions in boiling point cutoffs, there is overlap between distillate fractions. The

boiling point ranges correlate to carbon number and the higher the carbon

number, the higher the boiling point. However, structure will also influence

boiling point. Branched and aromatic compounds of the same carbon number

differ in boiling point from th eir correspond ing n -alkane analogs. For these

reasons, boiling point actually defines an approximate carbo n ran ge.

Figure 1 shows the relationship between boiling range and carbon number fo r

some common petroleum products. This figure clearly shows the overlap between

carbon ranges of different products as well as the overlap in corresponding ana-

lytical methods. For example, Figure 1 shows that an analytical method designed

for gasoline range o rganics may report some of the hydrocarbon s present in diesel

fuel. The same is also true for analytical tests for diesel range organics that willidentify some of the hydrocarbons present in gasoline contaminated soils. A more

detailed discussion of boiling point and carbon number classification as well as a

discussion of petroleum product composition, specification, product additives, and

weathering is provided in Appendix II: Chara cterization o f Petroleum P roducts.

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4

Figure1.S

ummaryofPetroleumProductTypesandTPHandTPHAnalyticalMetho

dswithRespecttoApproximateCarbonNumber

a

ndBoilingPointRanges.


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Ambiguous terminology associated with TPH methods presents additional diffi-

culty in interpreting results. Each method has its own designation. For example,

TRPH stands for tota l recoverable petroleum hydrocarbon s, D RO stand s for diesel

range o rganics, GRO stand s for gasoline range organics, and TPH -G stand s for

tota l petroleum hydrocar bon s-gasoline. Frequently a method n ame tha t cites a

prod uct - ga soline or diesel - only implies a carb on ran ge. For example, TPH-G

do es not n ecessarily imply tha t ga soline is present. These ab breviations may imply

different carbon ranges to different laboratories or states. TPH methods are not

optimized to identify product type. Even with improved, more detailed analytical

method s, identification of aged products may prove difficult.

There is a reason for the availability of a large number of TPH measurement

techn iques. Because petroleum and p etroleum-derived produ cts are such complex

mixtures, there is no single best method for measuring all types of petroleum

contamination. As shown in Figure 1, some methods are appropriate for gasoline-

contamina ted samples while others are designed for heavier hydrocarbo n con tam-

ination such as jet or diesel fuel. Some methods measure more compounds than

other m ethods because they employ more rigorous extraction techniques or mo re

efficient solvents. Other methods are subject to interferences from naturally occur-ring materials such as animal and vegetable oils, peat moss, dried grass, or humic

material in topsoil, which may result in artificially high reported TPH concentra-

tions. Some methods use cleanup steps to minimize the effect of nonpetroleum

hydrocarbons, with variable success. Ultimately, methods are limited by the extrac-

tion a nd cleanup efficiency and m easurement d evice detection limits.

The choice of a specific method should be based on compatibility with the par-

ticular type of hydrocarbon contamination to be measured. The choice may

depend upon state regulatory requirements for the type of hydrocarbo n conta mi-

nation suspected to be present.

3. 1 RISK IM PLICATIONS

TPH concentration data cannot be used to quantitatively estimate human healthrisk. The same concentration of TPH may represent very different compositions

and very different risks to h uman health a nd the environment. For example, two

sites may have TPH measurements of 500 ppm but constituents at one site may

include carcinogenic compounds while these compounds may be absent at the

other site. The risk at a specific site will change with time as contaminants evapo-

rate, dissolve, biodegrade, and become sequestered. A valid correlation between

TPH an d r isk would ha ve to be site- and time-specific, related to a single spill, and ,

even then, th e correlation might no t be the same around the periphery of a plume

where the rate o f compositional change accelerates.

Although the u tility of TPH dat a fo r risk assessment is minimal, it is an in expen-

sive tool tha t can b e used for three purpo ses: (1) d etermining if there is a prob lem;

(2) assessing the severity of contamination; and (3) following the progress of a

remediation effort. If TPH data indicate that there ma y be significant conta mina-tion of environmental media, other data can be collected so that harm to human

health can be quantitatively assessed. These other data can include target analyte

concentration data an d petroleum fraction concentration data o btained using new

fraction-based a nalytical method s developed b y the Working G roup a nd others.

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4. UNDERSTANDING THE PETROLEUM ANALYTICAL PROCESS: FROMSAMPLE COLLECTION TO MEASUREMENT

This volume focuses on three types of petroleum analytical methods:

method s that measure a TPH concentration;

method s that measure a petroleum group type concentration; and

method s that measure individual petroleum constituent concentrations.

These three types of methods measure different petroleum hydrocarbons that

might be present in petroleum-contamina ted environmen tal media. TPH method s

generate a single number that represents the combined con centration of a ll petro-

leum hydrocarbons in a sample, which are measurable by the particular method

(See discussion in Section 3 regarding limitations of TPH data) . Petroleum g roup

type method s separate and qua ntify different categories of hydrocarbon s (e.g., sat-

urates, aro matics, an d po lars/resins). The results of petroleum g roup type an alyses

can be useful for product identification because different products (e.g., gasoline,

fuel oil no.2, and jet fuel) can have characteristic levels of various petroleum

groups (see Appendix II for a detailed characterization of petroleum products).Individual constituent methods quantify concentrations of specific compounds

tha t might b e present in petroleum-con tamin ated samp les, such as benzene, eth yl-

benzene, toluene, and xylenes (BTEX), and polycyclic aromatic hydrocarbons

(PAHs). Co ncentration d ata for individual petroleum constituents can be used to

evaluate human health risk, provided the necessary toxicity data are available.

Although these three method types measure different petroleum hydrocarbon

categories, there are several basic steps that are common to the analytical process-

es for all methods, no m atter the m ethod type or th e environmen tal matrix. This

section will focus on th ese basic steps. Sections 5, 6 an d 7 review analytical metho ds

that can provide the three different types of petroleum concentration d ata.

Most of the common analytical steps are related to the separation of analytes of

interest from a sample matrix prior to their measurement. In general, these steps are:

Collection an d preservation - requiremen ts specific to environm ental matrix

and analytes of interest

Extraction - separates the analytes of interest from th e samp le matrix

Concentra tion - enhan ces the ability to detect an alytes of interest

Cleanup - may be necessar y to remove interfering compoun ds

Measurement - q uan tifies the an alytes.

Each step affects the final result, and a basic understanding of the steps is vital

to data interpretation.

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4.1 COLLECTION AND PRESERVATION OF ENVIRONMENTAL SAMPLES

The ability to collect and preserve a sample that is representative of the site is a

critically important step. Obtaining representative environmental samples is

always a challenge due to the heterogeneity of different sample matrices.

Additional difficulties are encountered with petroleum hydrocarbons due to thewide range in volatility, solubility, biodegradation, and adsorption potential of

individual constituents.

Most site investigations for assessment of petroleum hydrocarbon contamination

in the environment are regulated by the states. However, sample collection and

preservation recom men da tions follow U.S. EPA guidelines. A summar y of the m ost

comm only used guid elines is included in Table 1. It sho uld be no ted th at there

might be additional requirements in any given state. Before a sample is collected,

the particular state requirements must be investigated. Because of holding time

considerations, the labora tor y must be selected a nd notified prior to the collection

of the samples.

4.2 SAMPLE EXTRACTIONFor most an alyses, it is necessar y to separa te the ana lytes of interest from the m atrix

(i.e. soil, sediment, an d water). Extraction of analytes can b e perform ed using one

or more of the following metho ds:

Extracting th e analytes into a solvent

Heating the sample (used in the an alyses of volatile compounds)

Purging the sample with an inert gas (used in the ana lyses of volatile compounds).

There a re a variety of com mon sample extraction techn iques. See Table 2.

Soxhlet, sonication, supercritical fluid, subcritical or accelerated solvent, and

purge and trap extraction h ave been promulgated by the U .S. EPA as soil extrac-

tion methods. Headspace is recommended as a screening method. Shaking/vor-

texing is presently not approved by EPA, but is quite adequate for the extraction of

petroleum hydrocarbons in most environmental samples.

For these extraction methods, the ability to extract petroleum hydrocarbons

from soil and water samples depends on the solvent and the sample matrix.

Surrogates (compounds of known identity and quantity) are frequently added to

monitor extraction efficiency. Environmental laboratories also generally perform

matrix spikes (add ition of ta rget ana lytes) to determine if a nalytes are retained by

the soil or water matrix.

Solvents have different extra ction eff iciencies. Extracting th e same sample in the

same manner by two different solvents may result in different concentrations. The

choice of solvents is determined by many factors such as cost, spectral qualities,

meth od regulation s, extraction eff iciency, toxicity, an d a vailability. Methylene chlo-

ride has been the solvent of choice for many semivolatile analyses due to its highextraction efficiency, low cost, and specification by many state regulatory methods.

Chlorofluorocarbon solvents such as trichlorotrifluoroethane (Freon 113) have

been used in the past for oil and grease analyses because of their spectral qualities

(th ey do n ot ab sorb in the 2930 cm-1 infrar ed mea surement wavelength ) an d low

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8

TABLE1.

U.S.

EPA-RecommendedSampling

Protocols

SampleContainera

Analytical

Analytical

Ho

lding

Parameter

Method(s)

Media

Volume

Type

Preservativesc

T

ime

Trphb

EPA418.1

(IR);

water

1liter

Glassjar

with

acidfixpH

Documents

Total Petroleum Hydrocarbon Criteria Working Group Series Volume 1 Analysis of Petroleum Hydrocarbons in Environmental Media