PB84-238328
Developing Methods for
Analyzing Oil Dispersants in Seawater
SRI International, Menlo Park, CA
Prepared for
Municipal Environmental Research Lab.
Cincinnati, OH
Aug 84
U.S. DEPARTMENT OF COMMERCE
National Technical Information Service
NTIS
-------
PE84-238328
EPA-600/2-84-144
Aunust 1984
DEVELOPING METHODS FOR ANALYZING
OIL DISPERSANTS IN SEAWATER
by
D.L. Haynes, D.G. Kelly, J.H. Smith,
and E.L. Fernandez
SRI International
Menlo Park, California 94025
Grant No. R-807059-01
Project Officer
Leo T. McCarthy, Jr.
U.S. Environmental Protection Agency
Municipal Environmental Research Laboratory
Edison, New Jersey 08837
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI , OHIO 45268
REPRODUCED BY
NATIONAL TECHNICAL
INFORMATION SERVICE
US DEPARIMENI OF COMMERCE
SPRINGf IE10. VA 22161
-------
TECHNICAL REPORT DATA
(Please rrad Inuructions on the reverse before completing)
I REPORT NO.
EPA-600/2-84-144
4 TITLE AND SUBTITLE
DEVELOPING METHODS FOR ANALYZING OIL
DISPERSANTS IN SEAWATER
7 authorisi
D.L. Haynes, D.G. Kelly, J.H. Smith and
E.L. Fernandez
3. RECIPIENT'S ACCESSIOt*NO.
P88 & 2
S. REPORT OATE
Auoust 198&
6. PERFORMING ORGANIZATION CODE
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME ANO AOORESS
SRI International
Menlo Park, California 94025
10. PROGRAM ELEMENT NO.
CBRD1A
11. CONTRACT/GRANT NO.
R-807059-01
12. SPONSORING AGENCY NAME ANO AOORESS .
Municipal Environmental Research Laboratory-Cin., OH
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOO COVERED
Final.April 1980-April 1982
14. SPONSORING AGENCY CODE
EPA/600/14
15. SUPPLEMENTARY NOTES
Contact: John S. Farlow
(201) 321 -6631
16. ABSTRACT
An analytical method was sought for determining the concentrations of dispers-
ants in seawater contaminated with oil in both field and laboratory situations.
Methods of analysis for surfactants found in the literature included spectropho-
tometry, gas chromatography (GC), thin-layer chromatography (TLC), and high perform-
ance liquid chromatography (HPLC). References to collection, concentration, and
cleanup methods included liquid/liquid extractions, gas stripping, and solid sorbents.
Of seven dispersants tested, one contained solely anionic surfactants, three
contained only nonionic, and three contained both anionic and nonionic surfactants.
HPLC normal phase, reverse phase, and ion exchange column techniques were tried.
Detection methods included (1) direct measurement of the surfactants by tensammetry
and ultraviolet (UV) spectrometry, and (2) derivation of the surfactant with phenyl
isocyanate with subsequent measurement by UV spectrometry. The most promising method
of those tested was analysis of the phenyl isocyanate derivative of POE nonylphenol
by normal phase HPLC using UV spectrometry detection.
A method of collection, concentration, and cleanup of seawater solutions of dis-
persants containing oil was developed using the solid sorbent SEP-PAK C18* cartridge.
This sorbent successfully removed compounds that interfered with colorimetric tests.
* Waters Association, Inc., trademark
KEY WORDS ANO DOCUMENT ANALYSIS
a. DESCRIPTORS
l>. IDENTIFIERS/OPEN ENDED TERMS
c. COSATi Field/Group
1R DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (T.tii Repnn)
UJCLAS^IF TED
71 NO OF PAGES
35
22. PRICE
EPA Form 2220-1 (9-73)
-------
DISCLAIMER
Although the information described in this article has been funded
wholly or in part by the United States Environmental Protection Agency through
assistance agreement number R-807059-01 to SRI International, it has not been
subjected to the Agency's required peer and administrative review and there-
fore does not necessarily reflect the views of the Agency, and no official
endorsement should be inferred.
i i
-------
FOREWORD
The U.S. Environmental Protection Agency was created because of increasing
public and government concern about the dangers of pollution to the health and
welfare of the American people. Noxious air, foul water, and spoiled land are
tragic testimonies to the deterioration of our natural environment. The
complexity of that environment and the interplay of its components require a
concentrated and integrated attack on the problem.
Research and development is that necessary first step in problem solution;
it involves defining the problem, measuring its impact, and searching for
solutions. The Municipal Environmental Research Laboratory develops new and
improved technology and systems to prevent, treat, and manage wastewater and
solid and hazardous waste pollutant discharges from municipal and community
sources, to preserve and treat public drinking water supplies, and to minimize
the adverse economic, social, health, and aesthetic effects of pollution. This
publication is one of the products of that research and provides a most vital
communications link between the researcher and the user community.
This report describes research conducted to develop an analytic method
for determining the concentration of dispersants in seawater contaminated
with oil in both field and laboratory situations. The most promising method
of those tested was analysis of the phenyl isocyanate derivative of POE nonyl-
phenol by normal phase, high performance liquid chromatography using ultra-
violet spectrometric detection. Also, a method was developed for collection,
concentration, and cleanup of seawater solutions of dispersants containing
oil using a commercially available, solid sorbent cartridge.
Francis T. Mayo, Director
Municipal Environmental Research
Laboratory
i i i
-------
ABSTRACT
Research was conducted to develop an analytical method for determining
the concentrations of dispersants in seawater contaminated with oil in both
field and laboratory situations.
The literature was reviewed, focusing on the physical and chemical
properties of the surfactants that are used in oil dispersants and also on
methods for the analysis, collection, concentration, cleanup, and preserva-
tion of trace quantities of these surfactants in marine environments.
Methods of analysis for surfactants found in the literature included spectro-
photometry, gas chromatography (GC), thin-layer chromatography (TLC), and
high performance liquid chromatography (HPLC). Literature references to
methods of collection, concentration, and cleanup include liquid/liquid
extractions, gas stripping, and solid sorbents.
Seven commercially available dispersants were analyzed colorimetri-
cally to determine the class of surfactants (ionic or nonionic) that they
contained. Only one dispersant contained solely anionic surfactants. Of the
six other dispersants tested, three contained only nonionic surfactants and
the remaining three contained both anionic and nonionic surfactants.
Several instrumental methods of analysis were investigated, all of which
used HPLC as the method for separation of the mixed surfactants. Normal
phase, reverse phase, and ion exchange column techniques were tried. Detec-
tion methods included (1) direct measurement of the surfactants by tensammetry
and ultraviolet (UV) spectrometry, and (2) derivation of the surfactant with
phenyl isocyanate with subsequent measurement by UV spectrometry. The most
promising method of those tested was analysis of the phenyl isocyanate deriva-
tive of POE nonylphenol by normal phase HPLC using UV spectrometric detection.
A method of collection, concentration, and cleanup of seawater solutions
of dispersants containing oil was developed using the solid sorbent SEP-PAK
Ci8* cartridge. This sorbent successfully collected and concentrated surfac-
tants from seawater containing dispersed oil. Recoveries of POE nonylphenol
from collected samples were 100% under the conditions tested. Highly colored
compounds in oil, which interfere in colorimetric tests, were removed by this
sorbent.
This report was submitted in fulfillment of Grant No. R-807059-01 by
SRI International under the sponsorship of the U.S. Environmental Protection
Agency. This report covers the period April 21, 1980, through April 30,
1982, and work was completed as of April 30, 1982.
~Waters Association, Inc., trademark
i v
-------
CONTENTS
Foreword iii
Abstract iv
Figures vi
Tables vi
1. Introduction 1
2. Conclusions 2
3. Recommendations 3
4. Results and Discussion 4
Classification of Surfactants in Oil Dispersants 4
HPLC Detection and Separation Methods 4
Sample Collection, Concentration, and Cleanup 10
Appendices 13
A. Literature Search 13
B. Experimental Procedures 18
C. Oil Dispersant Product Sources 25
References 26
v
-------
FIGURES
Number Page
1 Tensammagram of n-dodecylbenzene sulfonate 7
2 HPLC traces of a) phenyl isocyanate, b) underived POE
nonylphenol, and c) POE nonylphenol derived with
phenyl isocyanate 9
B-l Diagram of the HPLC Tensammetric detection system .... 21
B-2 Tensammetric detection cell 22
TABLES
Number Page
1 Colorimetric Analyses of Oil Dispersants and Surfactants . 5
2 Evaluation of SEP-PAK C^g Cartridges as a Sorbent for
Nonionic and Anionic Surfactants 11
A-l Summary of Spectrophotometry Methods for the Analysis
of Surfactants 14
A-2 Summary of Chromatographic Methods for the Analysis of
Surfactants 16
A-3 Summary of Adsorption Media for Surfactants 17
vi
-------
SECTION 1
INTRODUCTION
The use of surface active agents (dispersants) to treat spilled oil is
becoming more accepted. The surfactants are incorporated into a complex
proprietary formulation that is applied to the oil spill either directly or
after dilution with seawater. The wake of the boat and/or the natural mixing
energy of the ocean causes the oil to disperse as fine droplets into the
water column, where the larger surface area of the droplets promotes chemical
and biological transformations of the oil.
Tests of dispersant effectiveness under actual field conditions have
been performed in Canada and Great Britain for years, and more recently in
the United States by the U.S. Environmental Protection Agency (EPA), and the
Southern California Petroleum Contingency Organization. Laboratory tests of
dispersant effectiveness and toxicity are also routinely made. In both field
and laboratory tests, the dispersed oil in the water column can be extracted
and quantitatively measured by spectrophotometry. However, no analytical
methods currently exist for measuring the amount of dispersant product in the
water column in either the presence or the absence of oil. Thus the concen-
tration of dispersant in the water column after application to a spill cannot
be measured. Also, the environmental fate of dispersion products has not
been studied because the rate of disappearance by either dispersion or by
chemical or biological transformation cannot be measured. Before these
studies can be performed, analytical methods for the dispersant products must
be developed.
Results of a literature survey (Appendix A) indicated that the following
research areas should be selected and investigated:
(1) Ionic classification of dispersant products by colorimetric methods;
(2) Development and evaluation of several high performance liquid
chromatography (HPLC) detection methods;
(3) Development and evaluation of several HPLC separation methods; and
(4) Evaluation of solid sorbents for collection of dispersant products
in marine environments.
1
-------
SECTION 2
CONCLUSIONS
The major active ingredients in oil dispersants were found to be anionic
and nonionic surfactants. Of the seven commercially available oil dispersants
tested, one contained anionic surfactants, three contained nonionic surfac-
tants, and three contained both anionic and nonionic surfactants. No cat-
ionic surfactants were found in any of the four oil dispersants tested.
Tensammetry was investigated as a method for detecting oil dispersants.
Our attempt at developing such a detection method was unsuccessful because of
(1) the limited information on the use of tensammetry, (2) the complexity of
the equipment and the sophistication of the technique, and (3) the high
detection limits we experienced. Tensammetry may be used in limited analyses
of surfactants, but it is much too complex and sophisticated for routine use.
A more practical approach is to derive the surfactants in oil dispersants
and analyze them by existing HPLC detection methods such as UV detection. We
have derived a polyoxyethylene (POE) nonionic surfactant with phenyl isocya-
nate, which increased its response by UV detection. Ion chromatography using
a conductivity detector should be explored as a method for anionic surfactants
Surfactants can be collected on solid sorbents. Both anionic and non-
ionic surfactants were successfully collected on SEP-PAK C^g cartridges
(Waters Associates, Inc.). These cartridges could also be used to concentrate
and isolate surfactants from potential interferences present in seawater and
oil. Other solid sorbents such as XAD resins used in amounts larger than are
available in the SEP-PAK C^g cartridges could be used to collect large-volume
samples.
2
-------
SECTION 3
RECOMMENDATIONS
Though several areas of investigation described in this report have
produced promising results, further work is required for adequate development
and validation of the methods of collection and analysis. The SEP-PAK Cis
collection method needs further testing, and other sorbents should be inves-
tigated. The phenyl isocyanate derivation method of analysis needs more
thorough testing, and a method for analysis of anionic surfactants needs to
be developed.
The collection method using SEP-PAK Cis cartridges has been shown to
collect, isolate, and concentrate several surfactants in the presence of
seawater and oil. Further work is necessary to test this method with other
surfactants and oil dispersants. Capacities for these surfactants and oil
dispersants in the presence and absence of oils should be determined.
Other sorbents such as XAD resins (Rohm and Haas, Philadelphia, PA) have
been successfully used in the collection of organics from water and should be
tested for use in collecting surfactants. XAD resins are available- in bulk
and could be used for collecting surfactants from larger volumes of water
than SEP-PAK Cis cartridges are capable of collecting. Simulated or actual
field tests of these sorbents should be made after laboratory evaluation of
their applicability to collections of surfactants from seawater containing
oi I.
The phenyl isocyanate derivation method combined with HPLC has shown
promising results as a quantitative analytical method in our limited tests.
More thorough testing of this method, including tests with varieties of
nonionic surfactants and oil dispersants, is necessary. This method of
analysis needs to be adapted for use with the sample collection method.
Methanol has been used to elute surfactants from SEP-PAK C^g. However,
because phenyl isocyanate reacts with alcohols, another solvent compatible
with the derivation procedure must be found or methanol must be removed from
the eluent before derivation.
A method of analysis is needed for anionic surfactants, which have been
shown to be present in oil dispersants. Ion chromatography using a conduc-
tivity detector or reverse phase HPLC using ion pairing and UV detection are
possible instrumental methods of analysis for anionics.
3
-------
SECTION 4
RESULTS AND DISCUSSION
CLASSIFICATION OF SURFACTANTS IN OIL DISPERSANTS
Since no information was available on the composition of commercially
available oil dispersants, an investigation was made to determine the types
of surfactants used in these dispersants. Seven oil dispersants were tested
using methyl orange*, Azure A*, and ammonium cobaltothiocyanate^ colorimetric
methods to determine the presence of cationic, anionic, and nonionic surfac-
tants, respectively. Surfactant standards were also tested to determine the
specificity of and interferences in each test. The detailed procedures of
these colorimetric methods can be found in Appendix B. The dispersants and
their manufacturers are listed in Appendix C. The results of these colori-
metric analyses are presented in Table 1. Although these test are not ex-
haustive, they show that the oil dispersants tested contained primarily
anionic and nonionic surfactants and no cationic surfactants. Test conducted
with standard anionic and nonionic surfactants showed no positive interferen-
ces of anionics in nonionic tests and vice versa. In the case of tall oil
fatty acids (an anionic surfactant), the Azure A analytical method for an-
ionics was negative. Therefore, negative Azure A tests of the oil dispersants
do not exclude tall oil fatty acids.
Since no evidence was found that oil dispersants contain cationic surfac-
tants, only anionic and nonionic surfactants were studied in the development
of sample collection and instrumental analytical methods for oil dispersants.
HPLC DETECTION AND SEPARATION METHODS
Several methods of analysis for oil dispersants, after collection and
isolation from the seawater-oil matrix, were tested. After a review of the
literature, HPLC was selected as the most promising analytical technique.
Two detection methods for HPLC were tested: tensammetry, which is a form of
polarography, and derivation of surfactants with ultraviolet (UV) absorbing
groups for UV detection.* After all potential possibilities for tensammetric
detection were exhausted, derivation was found to be the most promising
analytical technique for detecting oil dispersants.
* The two commonly used LC detectors, UV and refractive index (RI), have
several shortcomings for the detection of oil dispersants. Many dispersants
contain only aliphatic surfactants, which have little, if any, UV absorption,
and the sensitivity of the RI detector is not great enough.
4
-------
TAD Mi
COLORIMETKIC ANALYSES OF OIL D1 SPERSANTS AND SURFACTANTS
Methyl orange
method for
cationic
surfactants
(CS)
Azure A
for anionic
surfactants
(AS)
Ammonium
coba]tothiocyanate
method for nonLonii
surfactants
(NS)
Oil dispersants
Corexit 9527*
Gold Crew*
Sea Master, NS-555*
BP-J100X*
Conco K*
•Nokomis 3 Mi-Dee Formula 50*
AP*
Surfactant standards
POE tallow amine (CS)
Sodium lanryl sulfate (AS)
Tall oil fatty acids (AS)
Sodium n-dodecylbenzene sulfonate (AS)
Sodium petroleum sulfonate (AS)
POE nonylphenoL (NS)
Laurate of polyethylene glycol
400 (NS)
POE sorbiLan mono!aurate (NS)
+
+
+
+
+
+
+
+
+
+
+
+
+
+
Appendix C lor complete identification.
-------
Direct current (dc) polarography measures the current through an electro-
lyte solution as a function of the potential applied between two electrodes
(a reference and a working polarizable electrode) placed in solution. Alter-
nating current (ac) polarography measures the current produced when a small
amplitude (10-30 mV peak-to-peak) sinusoidal potential is superposed on the
dc potential. If the chemical of interest undergoes oxidation or reduction
at a certain dc potential, the current produced (Faradaic current) is usually
45° out of phase with the applied ac potential (the true phase depends on the
redox kinetics). Tensammetry, which is a form of ac polarography, however,
does not require the occurrence of a redox reaction for detection.^ Instead,
it measures the change in the capacitance of the electrical double layer
surrounding the working electrode (dropping mercury electrode of DME) by
measuring the current 90° out of phase with the ac potential (assuming no
Faradaic current). The change in capacitance is caused by sorption and
desorption of surfactants on the working electrode. Lankelma and Poppe found
that the potential where the concentration of surfactant is proportional to a
decrease in current over the widest range of concentrations is the valley be-
tween the two peaks (known as tensammetric peaks or waves) as shown in Figure
l.5
A method for using tensammetry as an HPLC effluent detector for surfac-
tants has been presented by Lankelma and Poppe.^ Because the sorbent system
used by Lankelma and Poppe was unavailable, several attempts were made to
find an HPLC solvent-sorbent system that would: (1) separate both ionic and
nonionic surfactants, (2) contain enough supporting electrolyte in the solvent
system to produce moderate to low cell resistances, (3) produce a significant
difference in the cell current, at a certain potential, and surfactant solu-
tion. Separation procedures were tested using sodium n-dodecyI benzene
sulfonate. Concentrations of sodium N-dodecylbenzene were high enough (100
ppm) that a UV detector could be used.
Two columns, a Waters jj-Bondapak Cjg reverse phase column and a Whatman
Partisil-10 SAX strong anion exchange column, were each tested with various
solvent systems. One solvent system for the reverse phase column fulfilled
the first criterion but not the third.°
A solvent system (see Appendix B) for the anion exchange column was found
that fulfilled the first and third criteria, but not the second. The cell
for tensammetric detection of the column effluent (see Appendix B) was
assembled, and chromatograms were run. An injection of a 34-ppm solution of
sodium n-dodecy1 benzene sulfonate in water was made for these runs. Tensam-
metric detection of the solvent was easily achieved. However, at surfactant
concentrations large enough for UV detection, the response of the tensammetric
detector to the surfactants was barely distinguishable from the baseline. We
varied the dead volume, mercury drop time, and dc potential to see if the
surfactant could be detected, but the results were negative.
Several factors could have been responsible for our inability to achieve
a working tensammetric detector. Low electrolyte concentrations and the
unavailability of electrical equipment for filtering the drop noise could
6
-------
VOLTS vs. SCE (mV)
(a) Supporting electrolyte: p.10 M Na2S04, 0.155 M acetic acid,
0.018 M sodium acetate.
(b) Supporting electrolyte and 108 ppm sodium dodecylbenzene
sulfonate.
Figure 1. Tensammagram of n-dodecylbenzene solfonate.
7
-------
have been responsible for our negative results. However, the sophisticated
equipment required adds a high degree of complexity to this technique.
The technique presented by Allen and Linder^ for determining the ethyl-
ene oxide oligomer distribution in nonionic surfactants using HPLC was then
investigated and shown to be a promising technique for analyzing oil disper-
sants. This technique involved the derivation of alcohol ethoxylate surfac-
tants with phenol isocyanate to give a urethane, a UV absorber.
<°> N=C=0 + ROH ®-Lc
no-r
Analysis is then made using HPLC with a normal phase column.
Since most commercial oil dispersants contain these types of surfactants,
these dispersants would be expected to be susceptible to this derivation and
analysis. Polyethoxylated nonylphenol, Corexit 9527, Conco K were derived
neat with phenyl isocyanate and analyzed by the method of Allen and Linder.
Using a UV detector, we obtained a strong response for both POE nonylphenol
and Corexit 9527 in the 2500 ppm range, as can be seen for POE nonlyphenol in
Figure 2. The derivation was attempted in acetonitrile, but no response was
obtained except for Conco K.
We were unable to fully evaluate this method for analysis because of the
major emphasis on development of a tensammetric detector. However, initial
results show that this method does work for the surfactants tested. Further
tests are necessary to thoroughly evaluate this method.
8
-------
TIME (min)
(a)
TIME (min)
(b)
TIME (min)
(c)
Figure 2. HPLC traces of (a) phenyl isocyanate, (b) underived POE
nonylphenol, and (c) POE nonylphenol derived with phenyl
isocyanate.
9
-------
SAMPLE COLLECTION, CONCENTRATION, AND CLEANUP
One solid sorbent was successfully tested as a means of collecting,
concentrating, and separating surfactants in oil dispersants from an
oil-seawater matrix. The sorbent tested was a SEP-PAK C^g cartridge manu-
factured by Waters Associates, Inc., Milford, Massachusetts. The sorbent
consists of a polymer cartridge filled with a reverse phase liquid chroma-
tographic packing. The cartridge is made to fit syringe Luer end fittings.
Samples and solvents are applied to the cartridge by syringe. The SEP-PAK
C^g cartridge is used for collecting samples in a polar solvent, such as
water. Polar compounds are not retained by the cartridge. The degree of
retention of nonpolar compounds is a function of the polarity of the eluting
solvent. Also, surface effects are important for the retention of the
surfactants, especially ionic surfactants. Adsorbed organics are eluted with
a less polar solvent.
This collection method was tested using standard surfactants in the
presence and absence of seawater and oil. POE nonylphenol and sodium lauryl
sulfate were used as representatives of nonionic and anionic surfactants,
respectively. Methanol was used to elute the surfactants from the cartridge.
The presence or absence of surfactant in the cartridge eluate tested was
determined by colorimetric tests. The ammonium cobaltothiocyanate method was
used for nonionics and the Azure A method for anionics. In both cases a blue
extraction solvent indicated the presence of the nonionic or anionic surfac-
tant, depending on the method used. The results of these tests are presented
in Table 2.
Oil is the only interference in the nonionic surfactant colorimetric
method. In the absence of oil and surfactants, neither methanol, methanol ex-
tracts of SEP-PAK C^g, nor seawater interfere in this method. The interfering
components of the oil that absorb at 610 nm are retained on the SEP-PAK C^g
and eluted with methanol are detected at 320 nm. Therefore, we have shown
that a nonionic surfactant can be collected from a sample containing seawater
and oil and detected colorimetrically without interference at 610 nm. Other
nonionic surfactants and oil dispersants should be tested using a variety
of crude oils to make sure that this method will work for a variety of sur-
factants and oils.
Both seawater and oil cause interferences in the anionic surfactant
.colorimetric analytical method. The interferences from seawater pass through
the SEP-PAK C^g and are not eluted by methanol with the surfactants. Again,
a wider variety of anionic surfactants and oils need to be tested to thor-
oughly validate this collection method.
Besides collecting and separating the surfactants from interferences,
the SEP-PAK C^g cartridges can be used to concentrate samples whose concen-
tration is too low for analysis. The tests whose results are shown in Table
2 were made using 100-ml samples containing about 10 ug ml"^ of surfactant
and about 1500 yg ml~l light Arabian crude oil. Quantitative recoveries of
the surfactants were achieved using three 2-ml methanol rinses of the SEP-PAK
10
-------
Table 2. Evaluation of SEP-PAK C^s Cartridges as a Sorbent
for Nonionic and Anionic Surfactant
Sample Adsorbed by Eluted with
SEP-PAK Cis methanol
Oil* in freshwater yes no
Seawater salts no no
Oil* in seawater yes no
POE nonlyphenol yes yes
in freshwater
POE nonylphenol yes yes
in seawater
POE nonylphenol in yes yes
seawater with oil*
Sodium lauryl sulfate yes yes
in freshwater
Sodium lauryl sulfate yes yes
in seawater with oil*
*Light Arabian crude oil
11
-------
C^g cartridge, which represents a concentration of these samples by more than
an order of magnitude. The maximum capacities for surfactants and crude oil
have not been determined for SEP-PAK Collections of varying amounts of
several surfactants and oil dispersants need to be made in the presence and
absence of crude oil to determine the surfactant capacities of SEP-PAK Ciq-
12
-------
APPENDIX A
LITERATURE SEARCH
Before the literature search was begun, we made the following three
assumptions about dispersant products applied to oil spills at sea:
(1) Dispersant products are complex mixtures of surfactants, buffers,
modifiers, and carriers. Surfactants will be the primary substan-
ces to be collected and analyzed. Of these, nonionic and anionic
surfactants are most prevalent. Cationic surfactants will not be
considered in this study.
(2) Dispersant products will be present in an aqueous (seawater) matrix
containing salts, petroleum products, biota, and other substances
likely to interfere with sampling and analytical methods.
(3) Dispersant products are expected to be present in seawater at
concentrations of at most 10 ppm.
The literature survey focused on physical and chemical properties and
methods for the analysis, collection, concentration, cleanup, and preservation
of trace quantities of surfactants in marine environments. The most relevant
references are summarized in Tables A-l, A-2, and A-3 and are discussed below.
There was much information on the analysis of surfactants, especially by
colorimetric methods. These methods are summarized in Table A-l, along with
detection limits and known interferences. These methods involve complexation
of the surfactant with a suitable reagent, extraction of the complexed
surfactant into an organic phase, and colorimetric determination of the
complex. Since the complexing reagent is frequently a metal complex, some
methods use atomic absorption spectrophotometry (AA) for detection of the
metal-surfactant complex. The colorimetric methods of analysis are generally
sensitive and rapid and require minimal equipment. However, they are
nonspecific and subject to interferences. Salts, especially CI" and certain
metal ions, interfere. Most colorimetric methods are unsuitable for direct
analysis of marine samples. Ocean waters may also contain natural surfactants
that interfere. The Azure A, ammonium cobaItothiocyanate, and methyl orange
methods listed in Table A-l were used in our studies to characterize some
commercial dispersants and to evaluate a solid sorbent collection method.
Less information was available on analytical methods based on chromato-
graphic separation. Chromatographic methods offer the advantages of selec-
tivity and the ability to separate interfering materials. It may be possible
13
-------
TABLE fl-1. SUMMARY OF SPECTROPHOTOMETRIC METHODS FOR THE ANALYSIS OF SURFACTANTS
Reagent
Reference Class
Limit of
detection
(ppm) Known interferences
Comments
Colorimetric methods
Methylene blue
8, 9 Anionic 0.025 Organic sulfates, sulfonates,
carboxylates, phosphates, and
phenols; CN" , CI", N02, SCN"
Requires 4-CHC13 extractions.
Azure A 2 Anionic
Copper(11)triethyl- 10 Anionic
enetetramine
Remacrylblau B 11 Anionic
Remacrylrot 2BL
Phosphomolybdic acid 12, 13 Nonionic
Dragendorf's reagent 14, 15 Nonionic
(KBiI4 + BaCl2)
Ammonium cobaltothio- 1, 16 Nonionic
cyanate
Ferrocyanic acid 17 Nonionic
Sodium picrate 18 Nonionic
0.2
0.014
0.5
0.1
0.1
NO3"", IICO3", S042", S032", CI"
Metal ions (e.g., Ca2+, Mn2+)
may interfere.
Alkaloids and many physiolo-
gical substances
(Fairly Sodium perborate
high)
0.1 Anionic surfactants >0-2 ppm;
cationic surfactants
Author claims better
suitability for seawater
than methylene blue.
Complex is light sensitive.
Single extraction gives 95%
recovery; CI", NO3, etc., do
not seriously interfere.
Anionic surfactants and mineral
salts do not Interfere.
Surfactants may be precipitated
or extracted in organic phase
Alcohols & anionic surfactants
do not seriously interfere.
Lengthy procedure.
Methyl orange 2 Cationic
Anionic surfactants do not
i ntor fere.
Atomic absorption
methods
Bis(ethylenediamine)- 19
Cu(11)
K2 [ Zn( I 1 ) (SCN)/,] 20
Anionic
Nonionic
0.0003
0.05
Organically bound Cu
c2-
Fe3+, Al3+, Cr3+;
cationic surfactants
Analysis as Cu by flameless AA.
Analysis as Zn by AA.
-------
to minimize cleanup procedures by use of chromatographic analysis and to
determine anionic and nonionic surfactants simultaneously. However, these
methods require more sophisticated equipment, generally in a well-equipped
laboratory, and are time-consuming. These methods are summarized in Table
A-2. Gas chromatography (GC) is usually not an appropriate method of
analysis for surfactants. Ionic materials, and nonionic substances of high
molecular weight, are generally not volatile enough for GC analysis.
However, nonionic surfactants have been derived, which increases somewhat
their vapor pressure or are analyzed by GC as their pyrolysis products.
Thin layer chromatography (TLC) and high performance liquid chromato-
graphy (HPLC) have been used to analyze all classes of surfactants.
Published methods are limited and are mostly intended for quality control,
not trace analysis. However, complex surfactant mixtures have been separ-
ated on normal phase, reverse phase, partition, and ion exchange columns.
Therefore, HPLC appears to be the method of choice for separation and
identification of dispersant products.
Detection after separation appears to be the limiting factor in TLC
and HPLC methods. Standard methods of detection (UV absorbance, refraction
index, electrochemical) are unsuitable for detection of small quantities of
these products. A tensammetric HPLC detector has been described that
responds specifically to surface active substances. This detector uses a
modified ac polarograph. Substances that adsorb at the mercury-solution
interface produce a change in the alternating current, giving rise to a
signal. The authors5 claim equivalent sensitivity to UV detectors, even
for nonaromatic surfactants. The HPLC separation/tensammetric detection
approach was the most promising method resulting from the literature survey,
and the primary one we evaluated as an analytical method for dispersant
products.
The literature survey also focused on methods to collect, concentrate,
cleanup, and preserve samples of trace levels of surfactants. Extraction
of surfactants into an organic phase has limited success. Surfactants are
designed to collect at the water-oil interface and do not partition cleanly
between phases. Wickbold^ described an apparatus for stripping nonionic
surfactants into an ethyl acetate phase by bubbling large quantities of
nitrogen through the aqueous phase. This technique is effective, but it is
time-consuming and unsuitable for field use.
There are indications that surfactants are more or less irreversibly
sorbed on charcoal and silica gel, which would be unacceptable collection
media. Several porous polymeric materials may be useful for concentrating
trace levels and eliminating interferences. These are summarized in Table
A-3. Amberlite XAD-2 and XAD-4 and open-pore polyurethane have been shown
to retain certain surfactants. Ion exchange resins may also be useful in
cleanup and concentration procedures. SEP-PAK C^g cartridges containing
reverse phase HPLC packing were evaluated for the collection of surfactants.
These cartridges were selected because they required a minimum of preparation
and pretreatment.
1-5
-------
TABLE A-2, SUHIWiT OF" CHPPttAJCGRApKJC HETKQOS FOR THE /LNAmiS OF SURFACTAhTS
keltcI '.c
Reference 1c. Clast limit Stationary phase Motile ptasg
e«tectlor
torments
TLC methods
??
%>; p?r-
fences) in seiwaiec.
DriCjendor-'i reaqent Abstract onfy.
HrLt methods
23
26
Arionic Not stated Amber!ite GC-50
(weakly basic
cation eictianje)
C:ticnic H;.t sla:fd Ar&erUte SC-1B
¦>?afcfy t = sr:
jT Cfi tidM-.Tje',
Ht+ [5 - G«is n die a s. Cig
lsoprcpanol/0.2 N Collection of fric-
HaCl tfons and titration
VrttianoV'9.5 « CoHectforr a' fnc-
NfC1 I'v'is and ItratJon
Ih-gti]
-Sniomc O PF»
Ant-artic, <1 pp»
nonionir
(rewsnsc
H.ethsncl VxatET,'
EC I:
!¦!
uicrasorfc SI 6'D-ODS Hethanol/Nuter -t U'i ai 221 nn
CCTHfl)^ 50^-
Tr Icresolp1i05.phate
(loo exchange)
9,1 H "KA^^Ofl ~
O.C3 H HaOflc +
B.li. II :W3 MCrl
T«vvsait^ieter
"swucni: Nst s-tatei ^epar&n flQ-S (semi- Methanol/water ftl
prep rpvfri« phase
^hijh)
28 Nonionic O.Ob pprn
* Hon ionic High
(i^yrene-
di vinyl h£r»z«?ne
AW)cj:L'Jjr sJeve
Zcfbdx-Lti {medium
?3'ar«iy JiE?rjn»2
f ^s = 1
Chi or o forrr i? hexj r*e IR
J:epU »e
UV at 2?6 run
licpropancl necets&ry
to leep surfactants
ifi 5G?UtfOrt,
JtetJrajio) necessary to
ksep 5.u"factBril; fn
5!er.
Paired 1cr\ tTiron'a^is-
graFhy. Sdnples
precoitc-efil rated
JUfM.
Paper de-scribes J ft
detail tensarmetric
4e^t:t:r,
flethod for polyethy-
lene gljrto) derivatives
Pap^r .flails entEi-
slve cleanup procedures
for oil arc surfdetdrrts
in Wiiter,
Wsthctf for ethurylated
nanylphenois.
29
¦to tonic
^ J9
Jnbe-1 ' t? XAD-2
Acet&nitrfW
vater -f tetrs-
= 1 b>l jiRicnlur
wl ts
•AIsti C. Ha>r«dTT, t.i, Pout Je c^jinLrs £ Co,, WTtmingtor, *tela*ar£, frivdt
UV at 25A m
Evaluation oF retention
on *10-2 -is eu net Inn of
coufter
e CDrirjiiicatioji.
-------
TABLE A-3. SUMMARY OF ADSORPTION MEDIA FOR SURFACTANTS
Adsorption medium Reference Class Method/comments
Amberlite XAD-1
Amber!ite XAD-4
Amberlite XAD-4
30
26
31
Open-pore polyurethane 32
Anionic,
cationic,
& nonionic
Anioni c
Nonionic
Anionic
Seawater acidified to pH 2, filtered through
0.5-/jm filter; eluted with ethanol. XAD-1 did not
retain carbohydrates, amino acids, proteins, or
phenols.
Samples acidified to pH 2, eluted with methanol.
Neutral solution resulted in poor retention.
Eluted with acetone. Polyethylene glycols of
MW <300 were not efficiently retained.
Eluted with methanol.
capacity than XAD-4.
Authors report greater
-------
APPENDIX B
EXPERIMENTAL PROCEDURES*
COLORIMETRIC METHODS
The Azure A, methyl orange, and ammonium cobaltothiocyanate methods
were used to measure anionic and polyoxyethylenated nonionic surfactants,
respectively, in surfactant standards and commercial oil dispersants.
AZURE A METHOD1
The following reagents, equipment, and procedures were used for this
colorimetric method. Reagent grade chemicals should be used.
Azure A Reagent—Dissolve 400 mg Azure A in 500 ml distilled H2O
containing 5 ml of 1.0 N sulfuric acid. Dilute to 1 liter with distilled water.
Stock Anionic Surfactant Solution--Weigh out 1.000 g. of the surfactant
and dissolve it in 1 liter of distilled water.
Standard Anionic Surfactant Solution--Di1ute 50.00 ml of the stock
solution to 1 liter with distilled water.
Buffer Solution--Prepare an aqueous solution containing 0.25 M citric
acid and 0.1 M disodium hydrogen orthophosphate.
Extracting Solvent--Chloroform.
Equipment-- Spectrophotometer capable of measuring absorbances at 623
nm, 250-ml separatory funnels, assorted graduate cylinders, assorted pipets,
filter funnels (65mm), 1-liter volumetric flasks, glass wool, and 1-cm
path length cuvettes.
Procedure--Pipet the water sample into a separatory funnel. Dilute
with distilled water to 50 ml if water sample volume is less than 50 ml.
Add 1 ml of Azure A reagent and 5 ml of the buffer solution. Mix well,
then add 25.0 ml of chloroform and shake vigorously for 30 seconds. Allow
the water and chloroform layers to separate, then filter the chloroform
layer through a glass-wool-piugged funnel into a 1 cm path length cuvette.
Measure the absorbance of the chloroform solution at 623 nm. Determine the
*A11 surfactant standards referred to in this report were reagent grade and
obtained from Chem Services, Media, PA.
18
-------
concentration of the anionic surfactant from a previously prepared calibration
curve of that same surfactant. Qualitatively, a clear colorless chloroform
layer indicates that little or no anionic surfactant is present, and a
clear blue chloroform layer indicates that anionic surfactant(s) are present.
Interferences--Inorganic and organic anions give a positive test.
Limit of Detection--! ppm of anionic surfactant.
METHYL ORANGE METHOD1
The reagents, equipment, and procedures used in this method of analysis
are listed below.
Methyl Orange Reagent—Dissolve 0.10 g of methyl orange powder in a
small amount of distilled water. Dilute to 100 ml or a concentration of
0.1% by weight.
Buffer Solution--Prepare an aqueous solution containing 0.25 M citric
acid and 0.1 M disodium hydrogen orthophosphate.
Extracting Solvent--Ch1oroform.
Equipment--Spectrometer capable of measuring absorbance at 415 nm, 250-
ml separatory funnels, assorted graduate cylinders, assorted pipets, filter
funnels (65 mm), 100-ml volumetric flask, glass wool, and 1-cm path length
cuvettes.
Procedure--Pi pet an aliquot of the water sample into a separatory
funnel and dilute to 50 ml with distilled water. Add 1 ml of the methyl
orange reagent and 5 ml of the buffer solution. Mix well, then add 25 ml
of chloroform and shake for 30 seconds. Allow the layers to separate (about
20 minutes) then filter the chloroform layer through a glass-wool-piugged
funnel into a 1-cm path length cuvette. Measure the absorbance of the
chloroform solution at 415 nm. A yellow chloroform layer indicates the
presence of cationic surfactant(s).
Limit of Detection--! ppm of cationic surfactant.
AMMONIUM C0BALT0THI0CYANATE METHOD2
Reagents, equipment, and procedures used for this method of analysis
are described below. Reagent grade chemicals should be used.
Ammonium Cobaltothiocyanate Reagent--Dissolve 120 g of ammonium
thiocyanate and 380 g of cobalt nitrate in distilled water and dilute to 1
liter. Extract twice with toluene to remove interferences.
Sodium Chloride—Reagent Grade.
Extraction Solvent--Toluene.
13
-------
Equipment--Separatory funnels, 250 ml, assorted graduate cylinders,
and pipets, filter funnels, glass wool, spectrometer capable of absorption
measurements at 320 and 610 nm, and 1-cm path length cuvette.
Procedure--Pi pet 100 ml of water sample into a 250-ml separatory
funnel. Add 15 ml of the ammonium cobaltothiocyanate reagent and 30 g of
the sodium chloride to the sample. Mix until all the sodium chloride is
dissolved. Add 25.0 ml of toluene and shake vigorously for one minute.
Allow the toluene and water layers to separate, then discard the water
layer. Filter the toluene layer through a glass-wool-plugged filter funnel
into a 1-cm path length curette. Measure the toluene solution at 320 or
610 nm. If oil or other UV-absorbing compounds are present in the water
sample, 610 nm should be used. The method is less sensitive at 610 nm, but
is less subject to interference than 320 nm. The concentration of
polyethoxylated nonionics can be determined from a previously prepared
calibration curve of the same presence of a polyethoxylated nonionic sur-
factant. A blue toluene layer indicates the presence of a polyethoxylated
nonionic surfactant. A clear colorless toluene layer indicates that the
polyethoxylated nonionic contains less than 3 polyethoxylate groups per
molecule, or that the amount present is below the lower limit of the test,
or that none is present.
Interferences--Polypropylbenzene sulfonate, n-alkyl sulfates, quarter-
nary ammonium compounds, and polyethylene glycols interfere with this test.
A mixed ion exchange resin can be used to remove cationic and anionic
i nterferences.
Limit of Detection--0.1 ppm of nonionic surfactant.
TENSAMMETRIC DETECTION OF SURFACTANTS5
Reagents, equipment, and procedures used for this method of analysis
are described below. Reagent grade chemicals should be used.
Eluting Solvent--Dissolve 0.499 g of sodium acetate trihydrate, 1.2 ml
of glacial acetic acid, and 0.284 g of anhydrous sodium sulfate in enough
Milli-Q water to make a 1-liter solution. Filter the solution through a
0.45-pm HA-type Milli-Pore filter.
Anionic Surfactant--Chem Service, sodium n-dodecylbenzene sulfonate.
Equipment--A Spectra-Physics 3500B, with a 1.0-ml sampling loop, and a
Whatman Partisil-10 SAX column. A Princeton Applied Research PAR 174/70
drop timer was used with a gravity fed dropping mercury electrode (DME), a
saturated calomel reference electrode (SCE), and a platinum counter electrode.
A PAR 174A polarographic analyzer, PAR 174/50 interface, and a PAR 124A
lock-in amplifier were also used for tensammetric measurement. Figure B-l
shows how the above equipment was connected.
procedure--Inject 100-ppm samples of sodium n-dodecylbenzene sulfonate
in water into the LC through the sampling loop. Direct the column effluent
(flow rate of 0.52 ml min~*) to the tip of the DUE (see figure B-2) (~l-2 mm
20
-------
Electrical connections
HPLC solvent flow
Figure B-l. Block diagram of the HPLC tensammetric detection system.
21
-------
MERCURY SUPPLY
Figure B-2. Tensammetric detector cell.
22
-------
distance between the tip of the DME and effluent outlet). The drop timer
then dislodges a drop from the DME (both 1 s/drop and 0.5 s/drop were
tried), and the measured current is directed to the polarographic analyzer,
which controls the applied dc potential (both -500 mV and -800 mV relative
to SCE were tried). The lock-in amplifier provides an ac potential of 10 mV
peak-to-peak at 50 Hz, for superposition on the dc potential. Adjust the
lock-in amplifier to detect the cell current 90° out of phase with the ac
potential.
HPLC ANALYSIS BY DERIVATION7
Reagents, equipment, and procedures used for this method of analysis
are described below.
Eluting Solvents--Fi1ter Burdick and Jackson dichloromethane and Fisher
HPLC grade methanol through 0.5-/jm type FH Milli-Pore filters and degas
before use.
Reagents--Surfactant Standard--Chem Service P0E nonylphenol.
Oil Dispersants—Corexit 9527 and Conco K. Eastman Kodak phenyl
isocyanate was used as the deriving agent.
Equipment--A Spectra-Physics 3500B, modified by removal of the mechanical
mixer, with the 100-jul sampling loop, and a Waters jj-Portasil normal phase
column. A Spectra-Physics 8200 UV detector was also used.
Procedure—Add approximately 10 pi of phenyl isocyanate to approximately
10 mg of surfactant in a lightly stoppered test tube. Heat the mixture to
50-60°C for 30 minutes. Allow the mixutre to cool to room temperature and
dilute with 4 ml of dichloromethane and 1% methanol. A 2500-ppm sample
results.
Analyze the 2500 ppm sample of the derived surfactants by HPLC, using
a solvent of 99% dichloromethane and 1% methanol to 89% dichloromethane and
11% methanol in one hour (eluting solvent flow rate of 2 ml min~l).
SURFACTANT COLLECTION METHOD
The following reagents and equipment were used in the collection and
subsequent elution of the surfactants studied in this work.
Sol vent--Use Water's SEP-PAK Cjs cartridges to collect, concentrate,
and separate the surfactants. Rinse each cartridge three times with 2-ml
portions of methanol followed by three 2-ml rinses of water.
Methanol^-Reagent grade.
Syringe--A syringe whose capacity will accomodate the water sample and
a 10-ml syringe for rinsing cartridges.
23
-------
Procedure--P1ace a seawater sample containing surfactants and oil in a
syringe with a cleaned SEP-PAK Cjg cartridge attached. Slowly force the
sample through the cartridge. Rinse the cartridge with three 2-ml portions
of purified freshwater. The cartridge can now be capped and stored for later
extraction, or the surfactant can be immediately eluted with three 2 ml por-
tions of methanol. Dilute the methanol extracts to the appropriate volumes
with water and analyze.
Solvent Capacity--The surfactant capacity of the cartridges have not
been determined. The greater the amount of oil and other strongly sorbed
substances, the lower the surfactant capacity will be.
24
-------
APPENDIX C
OIL DISPERSANT
Dispersant
Corexit 9527
Cold Crew
Sea Master, NS-555
BP-1100X
Conco K
Nokomis 3 Mi-Dee
Formula 50
AP
PRODUCT SOURCES
Manufacturer
Exxon Chemical Co.
Ara Chem, Inc.
808 Gable Way
El Cajon, CA
Whale Chemical Co.
58 Winant Street
Staten Island, NY
BP North America
620 Fifth Avenue
New York, NY
Continental Chemical Co.
270 Clifton Blvd.
Clifton, NJ 07015
Nokomis International, Inc.
Hayward, CA 94545
Atlantic-Pacific Co.
25
-------
REFERENCES
1. Wang, L.K., arid D.F. Langley, "Identification and Determination of Ionic
Surface Active Agents," Archives of Environmental Contamination and
Toxicology (1977), 5, 447-456.
2. Greff, R.A., E.A. Setzkorn, and W.D. Leslie, "A Colorimetric Method
for the Determination of Parts/Million of Nonionic Surfactants,"
J. American Oil Chemist's Society (1965), 42, 180-185.
3. Skoog, D.A., and D.M. West, Fundamentals of Analytical Chemistry. Holt,
Rinehart and Winston, New York, 1963. 786 pp.
4. Breyer, G. , and H.H. Bauer, Alternating Current Polarography and
Tensammetry in Chemical Analysis, Vol. XIII. P.J. Elwing and I.M.
Kolthoff, Eds. Interscience Publishers, New York, 1963, 288 pp.
5. Lankelma, J., and H. Poppe, "Design of a Tensammetric Detector for
High Speed High Efficiency Liquid Chromatography in Columns and Its
Evaluation for the Analysis of Some Surfactants," J. Chromatog. Sci.
(1976) , 14, 310-315.
6. Nakamura, K., Y. Morikawa and I. Matsumoto, "Rapid Analysis of Ionic
and Nonionic Homologs by High Performance Liquid Chromatography,"
J. American Oil Chemists' Society (1981), 58, 72-77.
7. Allen, M.C., and D.E. Linder, "Ethylene Oxide Oligomer Distribution in
Nonionic Surfactants via High Performance Liquid Chromatography (HPLC),"
J. American Oil Chemists' Society (1981), 58, 950-957.
8. Abbot, D.C., "Colorimetric Determination of Anionic Surface-Active
Materials In Water," Analyst (1962), 87, 286-293.
9. Standard Methods for the Examination of Water and Waste Water, 14th
Edition; APHA, AWWA, WPCF, 1975. Method 412A.
10. Gregory, G.R.E.C., "The Determination of Residual Anionic Surface-
Active Reagents in Mineral Flotation Liquors," Analyst (1966), 91,
251-257.
11. St. Janeva, "Extractional Spectrophotometric Determination of Anionic
Surfactants in Waters with Remacrylblau B and Remacrylrot 2BL," Talanta
(1978), 25, 279-282.
26
-------
12,
13
14
15
16
17
18
19
20
21
22
23
24
Schaffer, C.B., and F.H. Critchfield, "Solid Polyethylene Glycols
(Carbowax Compounds): Quantitative Determination in Biological Mate-
rials," Anal. Chem. (1947), 19(1) 32-34.
Stevenson, D.G., "The Absorptiometry Determination of a Nonionic
Detergent," Analyst (1954), 79, 504-507.
Burger, K., "Method for the Microdetermination and Trace Detection of
Surface-Active Compounds," Z. Anal. Chem. (1963), 196, 251-259; Chem.
Abstract 59:10769d.
Wickbold, R., "Determination of Nonionic Surfactants in River and
Wastewater," Tenside Detergents (1972), 9(14), 173-177; Chem. Abstract
77:117969d.
Boyer, L.L., et al., "Analytical Method for Nonionic Surfactants in
Laboratory Biodegradation and Environmental Studies," Environ. Sci.
Tech. (1977), 11(13), 1167-1171.
Schonfeldt, N., "A Method for the Quantitative Determination of Ethylene
Oxide Adducts in the Aqueous Solutions or Dispersions," J. American
Oil Chemists' Society (1955), 32, 77-79.
Favretto, L., B. Stancher, and F. Tunis, "Extraction and Determination
of Polyethylene Alkyl Ether Nonionic Surfactants in Water at Trace
Levels," Analyst (1978), 103, 955-962.
Gagnon, M.J., "Note on a Rapid and Sensitive Method for the Determination
of Anionic Detergents in Natural Waters at the ppb Level," Water
Research (1979), 13, 53-56.
Crisp, P.T., J.M. Eckert, and N.A. Gibson, "An Atomic Absorption
Spectrophotometry Method for the Determination of Nonionic Surfactants,"
Analy. Chim. Acta (1979), 104, 93-98.
Favretto-Gabriel1i, L., and Pertoldi Marietta, G., "Thin Layer
Chromatographic Determination of Nonionic Surfactants in Seawater,"
Ann. Chim. (Rome, 1973), 63(11-12), 807-814; Chem. Abstract 82:115739h.
Goretti , G., A. Liberti, and B.M. Petronio, "Nonionic Surfactants
Determination by Channel Thin-Layer Chromatography," Riv. Ital. Sostanze
Grasse (1975), 52(5), 165-167 ; Chem. Abstract 83; 133841k.
Fudano, S., and K. Konishi, "Separation and Determination of Mixtures
of Anionic Surface-Active Agents by Salting-out Chromatography," J.
Chromatog. (1973), 77, 351-355.
Fudano, S., and K. Konishi, "Separation and Analysis of Cationic
Surface-Active Agents by Salting-out Chromatography," J. Chromatog.
(1973), 87, 117-124.
27
-------
25. Parris, N., "Surfactant Analysis by High Performance Liquid Chromatography:
I. A Rapid Analysis for Mixtures of Amphoteric Surfactants and Soap,"
J. American Oil Chemists' Society (1978), 55, 675-677.
26. Taylor, P.W., and G. Nickless, "Paired-Ion High-Performance Liquid
Chromatography of Partially Biodegraded Linear Alkylbenzenesulphonate,"
J. Chromatog. (1979), 178, 259-269.
27. Coupkova, M., et al., "Determination of Free Polyethylene Glycols in
Ethoxylated Derivatives by Liquid Chromatography," J. Chromatog. (1978),
160, 73-80.
28. Cassidy, R.M., and C.M. Niro, "Application of High Speed Liquid
Chromatography to the Analysis of Polyoxyethylene Surfactants and
Their Decomposition Products in Industrial Process Waters," J. Chromatog.
(1976), 126, 787-794.
29. Rotsch, T.D., and D.J. Peitrzyk, "Ion-Interaction in High Performance
Liquid Chromatography of Benzenesulfonic Acids on Amberlite XAD-2,"
Anal. Chem. (1980), 52(8), 1323=1327.
30. Riley, J.P., and D. Taylor, "The Analytical Concentration of Traces of
Dissolved Organic Materials from Seawater with Amberlite XAD-1 Resin,"
Analy. Chim. Acta (1969), 46, 307-309.
31. Jones, P., and G. Nickless, "Characterization of Nonionic Detergents
of the Polyethoxylated Type from Water Systems: I. Evaluation of
Amberlite XAD-4 Resin as an Extractant for Polyethoxylated Material,"
J. Chromatog. (1978), 156, 87-97.
32. Smith, C.M., and J.D. Navratil, "Removal and Preconcentration of
Surfactants from Wastewater with Open-Pore Polyurethane," Separation
Science and Technology (1979), 14(3), 255-259.
28
------- |