NAT'L INST OF STAND & TECH

A111Q7 3TD113

NBSIR 83-2733

Characterization of Controlled

Release Dynamics and

Identification of Species Released

From OMP Impregnated Wood

Pilings

U S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Measurement Laboratory

Center for Materials Science

Inorganic Materials Division

Chemical and Biodegradation Processes Group

Washington, DC 20234

July 1983

Prepared for —QC—

100

,1156

83-2733

The Naval Civil Engineering Laboratory

Code L-52

Port Heneme, CA 93043

C , 2

NATIONAL BUFf.AU OF STANDARDS

UL'KAinr AUG iy 1983

NBSIR 83-2733

OoV O-CC- - o<" C • ©-o \oO

CHARACTERIZATION OF CONTROLLED

RELEASE DYNAMICS AND

IDENTIFICATION OF SPECIES RELEASED

FROM OMP IMPREGNATED WOOD

PILINGS

W. R. Blair, E. J. Parks, and F. E. Brinckman

U S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Measurement Laboratory

Center for Materials Science

Inorganic Materials Division

Chemical and Biodegradation Processes Group

Washington, DC 20234

July 1983

Prepared for The Naval Civil Engineering Laboratory

Code L-52

Port Heneme, CA 93043

U S. DEPARTMENT OF COMMERCE, Malcolm Baldrige, Secretary

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director
..

‘
CHARACTERIZATION OF CONTROLLED RELEASE DYNAMICS AND IDENTIFICATION

OF SPECIES RELEASED FROM OMP IMPREGNATED WOOD PILINGS

W. R. Blair, E. J. Parks, and F. E. Brinckman

Inorganic Materials Division

National Bureau of Standards

Washington, DC 20234

ABSTRACT

Tin containing organometal 1 ic polymers (OMP) are becoming an

increasingly important class of compounds finding application in marine

environments as antifouling and preservative agents. To provide accurate

estimates of service life and reliability in service, new analytical

methods are needed for the identification and measurement of the toxic

species being delivered by the OMP. This report is concerned with the

following: identification of parent tin species; identification of species

released from OMP impregnated wood pilings; and preliminary determination

of the rate of tin release from impregnated pilings. Additionally, the

influence of microbiological activities on the release process is considered in assessing the effectiveness and ultimate fate of the toxic species

responsible for the anti fouling and preservative properties of the OMP

formulation. Data from release rate measurement experiments are presented,

along with chromatograms providing speciation data on parent tin compounds

in the pilings and released compounds in the aqueous phase. Discussion

of areas for continued research are presented.

KEY WORDS: atomic absorption spectrophotometry; cation exchange chromatography; high pressure liquid chromatography; i_n situ polymerization;

controlled release; organometal 1 ic polymers; size exclusion chromatography;

tri butyl tin
1 . Introduction

The United States Navy is investigating the use of tin containing

organometal 1 ic polymer (OMP) formulations as anti fouling agents and

wood preservatives. The OMPs are prepared by copolymerization of two

or more monomeric species, typically esters of methacrylic acid, e.g.

methylmethacrylate (MMA) and tributyltin methacrylate (TBTM). Coated

on ship hulls, copolymers of MMA and TBTM provide years of anti fouling

protection in the marine service environment (1). In the case of wood

pilings, the respective OMP monomers impregnate the wood and are

believed to undergo reactions, including polymerization, i_n situ (2).

Questions and problems arise from the perspectives of longevity in

service and environmental impact. What is the chemistry of reactions

that occur in wood pilings? How rapidly do the wood pilings lose toxic

tin-bearing moieties? What chemical species actually migrate into the

environment? What is their probable effect on marine organisms in the

immediate vicinity of the pilings? How long will the OMPs remain

effective? The leaching mechanism, not yet fully understood, depends

on many factors such as: the extent of polymerization i_n situ ; the

nature of surface reactions between wood components and the tin-bearing

moieties; and the chemical reactions involved in transfering the tin

species from the wood-polymer matrix into the aqueous environment.

Samasekharen and Subramanian state, "The identification of the chemical

species will enable one to evaluate the change in bulk characteristics

of the coatings as leaching progresses. The knowledge of this chemical

moiety is a prerequisite for a meaningful study of the rate of leaching

and the mechanism of release." (3)
Our laboratory, at the request of the Naval Civil Engineering

Laboratory (NCEL), initiated an investigation into slow-release processes

under controlled conditions. We were provided with two debarked southern

yellow pine wood posts (3 1/2 feet long and approximately 4 inches in

diameter). One post had been impregnated with a TBTM and MMA mixture

(Piling No. 3-1), and one impregnated with TBTM and glycidyl methacrylate

(GMA), (Piling No. 4-5). This report summarizes preliminary research

initated in FY82 to investigate the performance of these OMP impregnated

wood pilings in a simulated marine environment. Specific activities

i ncl ude:

-Development of methods for the measurement of total tin release from

OMP impregnated wood pilings into artificial estuarine water

-Speciation of aqueous tin bearing moieties released from OMP impregnated

pi 1 ings

-Size exclusion chromatography (SEC) of tetrahydrofuran (THF) extractable

components of the material impregnating the wood

-Microbiological monitoring of aquatic bacterial cell numbers prior to

and during release of organotin species

-Assessment of most profitable areas for continued research

2. Experimental

2.1 Vessels, Solutions, and Sample Preparation

In two sets of experiments described below, the rates of total tin

release (leach rate) were measured for sample specimens taken from

pilings 4-5 and 3-1. The pilings were cut with a hand saw having a
steel 10 point cross-cut blade with teeth hardened by heat induction,

into smaller sections for use as test specimens. Pyrex glass jars were

used as containers for water and piling specimens. The jars were

cleaned prior to use, first with warm water and soap, then by leaching

for several days with aqueous 10% HNOg. Following acid leaching, the

jars were rinsed 4 to 5 times with deionized water (resistance of 15 to

18 MQ/cm, Culligan Aqua Suma 36, Culligan Corporation, Northbrook, IL).

The following salts, in grams per liter, were added to deionized water:

NaCl , 24.0; MgC^^h^O, 5.0; MgSO^TF^O, 7.0; KC1, 0.7, producing an

artificial estuarine water with a total salt content of 15.24 parts per

thousand. All salts used in preparation of the artificial estuarine

water were of reagent grade. The formula for the artificial estuarine

water was obtained from a personal communication with the Department of

Microbiology at the University of Maryland.

2.2 Piling Release Rate Determination

Two separate leaching experiments were performed. The first was a

small scale test conducted primarily to determine if there would be a

large initial release of tin soon after the pilings were exposed to

water. The second experiment, with a ratio of wood area to water

volume of approximately half that of experiment 1 (see table 1), was

considered better suited for resolution of both the initial rise in tin

concentration as leaching started and long term monitoring of the tin

concentration. Except for the differences in water volume and size of

piling specimens used, the two leach rate experiments were performed

identical ly.
Table 1

Piling Specimen Data

Experiment No. 1

Diameter: 11.4 cm Length : 3.5 cm

? Area exposed to water: 228.3 cni Pyrex jar water volume: 2.0 L

? ? Ratio, wood area/water volume: 228.3 cni /2.0 L = 114.15 cni /L

Experiment No. 2

Diameter: 11.4 cm Length : 45.0 cn^overall, 22.0 cm immersed

Area exposed to water: 1000.3 cni Pyrex jar water volume: 16.0 L

? ? Ratio, wood area/water volume: 1000.3 cm/16.0 L = 62.5 cm /L

In the initial release rate measurement experiment (experiment 1),

sections of the pilings 3.5 cm thick were allowed to float in Pyrex

glass jars containing 2 liters of artificial estuarine water. The

piling sections rapidly absorbed water and settled so that all but

their upper surface was exposed to the water, presenting a total area

? of 228.3 cm to the water. In the second experiment, the piling sections

were suspended in the jars by clamps attached to the jar covers.

Twenty- two centimeters of their length was exposed to the water, presenting

2 a total surface area of 1000.3 cm to the water.

The water was stirred constantly by magnetically driven teflon (PTFE)

covered stirring bars rotating at 650 rpm. Water samples of 1.0 mL

volume were withdrawn periodically through small bore teflon tubes

(1.0 mm I.D.) connected to plastic syringes. Teflon (PTFE) tubing and a

syringe for sample withdrawal was provided for each jar. Samples were

dispensed directly into polystyrene cups which fit into an auto sampler

on a graphite furnace atomic absorption spectrophotometer (GFAA) (Model
460 Perkin Elmer, Norwalk, CT). GFAA determinations for total tin were

started immediately after the jars were sampled. Sampling continued

for 19 days and 35 days respectively, in experiments 1 and 2. Table 2

lists the GFAA parameters employed for aqueous sample analyses and for

the GFAA when used as a HPLC detector.

Table 2

GFAA Parameters: General

Lamp: Tin Electrodeless discharge, 8 watts

Wavelength: 224.6 nm Slit width: 0.7 nm Integration time: 8.0 seconds

D2 Background correction on at all times

Graphite Furnace: Aqueous samples

Drying, 50 sec at 125 °C

Charring, 30 sec at 150 °C

Atomization, 6 sec at 2700 °C

GFAA Parameters: HPLC Detector

Parameters as above with the following exceptions:

Graphite Furnace: SCX Chromatography

Drying, 10 sec at 90 °C

Charring, 10 sec at 90 °C

Atomization, 6 sec at 2700 °C

Graphite Furnace: SEC Chromatography

Drying, 10 sec at 100 °C

Charring, 10 sec at 200 °C

Atomization, 10 sec at 2700 °C

Each time total tin determinations were made, the GFAA was calibrated

with freshly prepared tri butyl tin chloride standards. Calibration curves

typically contained 4 to 5 points with 4 to 6 replicates run at each point.

For the 20 calibrations performed during the course of experiment 2 correlation coefficients of 0.967 to 0.998 were obtained, with an average

value and standard deviation of 0.992 ± 0.008.
3. Chemical Speciation of Materials Released from Piling and Solvent

Extracts

3.1 Tin Speciation Methodology

Chemical speciation of the tin compounds in the aqueous piling

leachates and THF extracts of the OMP impregnated pilings was performed

by coupled liquid chromatography-atomic absorption spectrophotometric

(HPLC-GFAA) methods previously developed in our laboratory (4,5). In

figure 1 is given a block diagram of the HPLC-GFAA analysis system.

Samples are injected into flowing eluents at the sample injection

valve. Analytes separated on the chromatographic column are detected

by one or more of the following on-line detectors: ultraviolet absorption,

differential refractive index, or element specific GFAA. The same

HPLC-GFAA apparatus, with the appropriate analytical columns and solvents,

was used for both cation exchange chromatography (SCX) for the speciation

of tin-bearing moieties in aqueous solution, and for size exclusion

chromatography (SEC) of the THF extracts of the material impregnating

the pilings. The application of SCX and SEC chromatography for the

characterization of organometal 1 ic compounds has been described in

detail elsewhere (6,7). Column calibration was performed with polystyrene

standard samples of known molecular weight [7]. System parameters for

the above analyses are listed in table 3.
Table 3

Chromatographic Parameters

SCX Chromatography

Mobile Phase: Methanol/Water, 70%/30% with 0.08 M Ammonium Citrate

Flow Rate: 0.5 mL/min for 15 min, then 1.5 mL/min for 10 min

Analytical Column: Partisil PXS 10/25 SCX Whatman, Inc., Clifton, NJ

Detectors: GFAA and UV fixed wavelength at 254 nm

SEC Chromatography

Mobile Phase: THF

Flow Rate: 0.5 mL/min 0

Analytical Column: 1000 A pStyragel (one) Waters Assoc., Inc. Milford, MA.

Detectors: GFAA and Differential Refractive Index
3.2 Sample Preparation for Chromatography

For chemical speciation of the tin compounds present in the aqueous

solution by SCX chromatography, an extraction of the aqueous solution

was performed. Eighteen milliliters of water and 2.0 mL of chloroform

were added to a glass 30 mL separatory funnel and mechanically shaken

for a minimum of 30 minutes. The chloroform fraction was then injected

(250 pL) into the HPLC-GFAA. Extracts from piling 4-5 were injected

directly. Due to higher tin concentrations, extracts from piling 3-1

were diluted 1:1 with chloroform prior to injection. The retention

times of authentic tributyl tin chloride and dibutyltin chloride,

dissolved in chloroform, were determined for comparison with the retention times of peaks present in chromatograms of the leachate water

extracts.

To obtain samples for SEC chromatography, pieces of the pilings

were placed in round bottom flasks and immersed in THF for 3 days. The

flasks were swirled manually from time to time. Twenty microliter

volumes of the THF extract solutions were injected into the HPLC-GFAA,

followed by injection of discrete volumes of THF containing 1% (v/v) of

glacial acetic acid to effect desorption of cationic tin-bearing species

not otherwise eluted from the column (8). The amount of tin-bearing

species recovered in SEC-GFAA was determined by collecting all of the

eluent, except that consumed by the GFAA, and comparing its tin content

to that of the injected sample.
3.3 Biological Monitoring

No attempt was made to produce or maintain sterile conditions in

the release rate measurement experiments. Several factors influenced

this decision. In considering the possible methods available for

sterilizing the piling sections (dry heat, autoclaving, or toxic gas),

no method seemed to eliminate the concern that the sterilization process

itself might result in chemical or physical changes in the pilings that

would modify either the release mechanism or the species of tin released

from the pilings, or both. The length of time the controlled release

experiments were to run also presented a problem. Even if sterile

conditions were produced at the beginning of the experiment, the size

of the piling sections and the containing vessels, and the necessity

for frequent sampling over a relatively long period of time would make

maintenance of sterile conditions impossible without much more elaborate

containment facilities.

Finally, it is reasonable to investigate possible microbial mediation of the release process, as clean surfaces become rapidly colonized

by a variety of microbiota following their immersion in sea water (9).

Prior to placing the piling test specimens in the water to begin

experiment 2, the bacteria in the containing vessels were counted by

epi f 1 uorescent microscopy. In this technique, a dye which fluoresces

in the presence of DNA is used to make the bacterial cells in the

sample visible for counting. At the conclusion of the experiment, the

bacterial population was again counted.
4. Results and Discussion

4.1 Controlled Release: Total Tin Determination

The results of GFAA determinations of total tin in the release

experiments are shown in figures 2 to 5. In figures 2 and 3, the data

from experiment 1 are plotted. As mentioned above, experiment 1 was

designed primarily to discover if a large amount of tin, perhaps

unreacted TBTM monomer on the surface of the piling, would be released

rapidly upon exposure of the piling to water. Figures 2 and 3 indicate

no rapid, initial release of tin.

The data from experiment 2 are plotted in figures 4 and 5. Despite

the frequent calibrations of the GFAA, the data from both experiments

show considerable scatter from point to point. Early in the experiment,

this scatter was attributed to surface adsorption of tin to the glass

container walls of the containing vessels, but a closer examination of

the measurement process revealed that a significant signal interference

in the graphite furnace was influencing the total tin determinations.

Total tin levels were determined by direct analysis of the aqueous

solutions by GFAA. It was discovered that sodium chloride, present in

quantities as low as 0.02 ppt, produced a significant attenuation of

the tin signal in the GFAA. A charring step might be included in the

GFAA furnace program to help eliminate signal problems produced by

components in the sample matrix. Charring temperatures high enough to

char off the interfering salts, however, would also be high enough to

volatilize organotins from the sample, causing a signal loss of greater

magnitude than the suppression originally produced by the salts.
Because of these problems with signal suppression in direct GFAA analyses

of the aqueous solution, the figures presented for experiments 1 and 2

represent the relative change in tin concentration taking place in the

containing vessels, not the quantitative total of tin released. Further

release studies were postponed at this point, and time was devoted to

development of a quantitative method for the measurement of organotin

compounds in saline media.

To overcome the signal suppression caused by the salts in the

samples an extraction technique was developed in which the aqueous

solution is extracted with hexane, then washed with deionized water to

remove salts. The extractable organotin concentration is determined by

GFAA. Recoveries of tri butyl tin chloride spiked into saline water are

on the order of 90 to 95 per cent. We have found that samples of

tri butyl tin chloride in hexane, are detectable at ppb levels by tin

specific GFAA with signal enhancement by ammonium dichromate. The

salts present in a saline aqueous medium, or in an unwashed hexane

extract, both suppress the tin signal and eliminate the di chromate

enhancement effect. Current experimental results indicate that quantitation of Bu

3

SnCl in saline water is feasible at levels below ppb, as

well as the ppb quantitation already accomplished. The above extraction

method will be employed in all future release rate measurement experiments.

At the conclusion of experiment 2, the above method was applied to

determine the total extractable organotin concentrations in the aqueous

solutions. The values obtained were used to calculate a release rate

for the pilings. These preliminary results are summarized in table 4.

The release rate has been expressed as the microgram amount of tin

released per square centimeter of wetted piling surface, per day.
Table 4

Piling Number Leach rate

3-1 2

1.18 pg/cm /day

4-5 2

0.31 pg/cm /day

4.2 Speciation of Organotins in Aqueous Solutions and Solvent Extracts

4.2.1 SCX Chromatography

The results of SCX-HPLC-GFAA speciation of tin compounds extracted

from the aqueous solutions by chloroform are shown in figure 6. A

large signal is seen in the chromatograms of piling 3-1 and 4-5 samples

at approximately 11 minutes, which corresponds to the retention time

of tributyl tin cation. Of particular interest, however, is the small

signal seen at aproximately 20 minutes, which corresponds to the

retention time of di butyl tin cation. The origin of this small peak is

of considerable interest, as it could have important implications for

the future development of OMPs for antifoul ng applications. The

I di butyl tin peak may be representative of a small amount of impurity

present in the TBTM monomer used in forming the OMP in the wood, or

possibly a result of microbiological or chemical degradation of the

tri butyl ti n.
4.2.2 SEC Chromatography

The results of SEC-HPLC-GFAA analysis of the THF extracts from the

pilngs, as received, are shown in figures 7 and 8. Large differences

are apparent in the two figures and in table 4, which summarizes the

chromatographic data. In each sample, both the quantity and molecular

weight (MW) of the polymerized species show unique characteristics.

Polymerization may not predominate in either sample, as evidenced by

the relatively large proportions of low MW extractable species seen in

the ARI chromatograms of both piling 3-1 and 4-5.

The species desorbed by acetic acid from the crossl inked polystyre

chromatographic packing probably is a tin-bearing cation adsorbed on

electron-rich aromatic groups (10). The monomer fraction consists of

neutral tin-bearing species (e.g. , methacrylic esters). The high MW

species probably represents the copolymer formed in situ, although

homopolymerization of TBTM cannot be ruled out until the samples are

characterized by off-line Fourier transform nuclear magnetic resonance

(FT-NMR).

The THF extract of piling 3-1, which used TBTM and MMA precursors,

has an extractable polymer content five times greater than that seen in

sample 4-5, which used TBTM and GMA precursors. Nevertheless, the

total tin content, as determined by washed hexane extract, of the

aqueous solution in which piling 3-1 was immersed, exceeded that from

piling 4-5 by nearly four times. Thus, the higher quantity of extractable polymer has less correlation with tin release than the choice of

co-monomer. This indicates the need for further characterization of
the impregnated wood fibers; physical examination by microscope, as

well as NMR and mass spectroscopic characterization of molecular species.

Table 5

SEC Chromatographic Data

Piling

Number

Polymer

Fraction

Fractional Distribution

of Tin

Apparent Tin

Recovery

MW MWD Polymer3

(%)

Monomer

(%)

Adsorbed0

Species

(%) (%)

3-1 9350 2.29 10.1 10.8 79.1 10

4-5 5280 3.88 2.1 9.9 88.0 86

3

1000 to 100,000 dal tons

c 100 to 1000 dal tons

aesorbed by acetic acid

4.3 Biological Activity

Bacterial species resistant to organotins can be readily isolated

from environments stressed by industrial impact (11). The means by

which the bacteria acquire their resistance to organotins (and other

metals) has not yet been defined. Resistance could be conferred by

constitutive or induced intracellular enzymes (12,13). Ability to

metabolize or degrade organotins may be aquired by similar routes;

resistance and degradation ability could even be transfered together.

Regardless of the method by which the bacteria acquire resistance

and or degradation ability, the fact remains that such ability can be

readily transferred through a bacterial population. The possibility is

very real that if degradation ability exists, the widespread use of

organotin anti foul ants could produce a selection in the natural community
for organisms resistant to and able to degrade the organotin toxicants

incorporated in the OMPs. The effectiveness of the OMPs might slowly

diminish as the natural bacterial population comes to contain more and

more resistant/degradative members.

During the course of experiment 2, the bacterial cell count in the

containing vessels increased. The data are presented in Table 6. This

increase in cell count is attributed to several factors; an increase in

available nutrients and surface area following immersion of the pilings,

and minimal effect of tributyltin on a resistant microbial population.

Follow-up studies on the ability of this tributyltin resistant population

to degrade tributyltin are planned.

Table 6

Pi 1 i ng Cell Count Prior to Cell Count 36 days After

Number Immersing Pilings Piling Immersion

3-1 6.39 x 10

5 2.96 x 10

7

4-5 3.91 x 10

5 6.14 x 10

6

5. Conclusions and Areas for Further Research

The experience gained during the course of this investigation has

resulted in a thorough examination of various methods for determining

organotin release rates. The results indicate that emphasis must be

placed on two areas: measurement of the initial release kinetics to

assess environmental impact, especially important if relatively large

quantities of tin are released during the initial phases of exposure to

the aqueous environment; and long-term monitoring to determine the
steady-state release rate, allowing predictions of piling longevity to

be made. In view of the above recommendations, a new experimental

design has been formulated for use in future release rate studies. The

closed system, used in this study would still be employed. Water would

be circulated around the test specimens. An activated carbon filter

would be incorporated into the water circulation system to continually

remove organotin from the aqueous solution, preventing a slow increase

in tin concentration from influencing the long term release rate. The

total tin determinations would be performed using the extraction method

described in section 4.1 above, allowing the release rate studies to be

conducted in saline water at ocean salinity levels.

The task of evaluating the extent of polymerization of the TBTM

and MMA or GMA co-monomers in the wood pilings is quite difficult.

Recent evidence (14) suggests that pStyragel , the SEC column packing,

is capable of cleaving organotin species from polymer chains. This

happens if the column is not previously conditioned with an organotin

cation and may partially account for the high concentration of adsorbed

species seen in Figures 7 and 8. This question will be reinvestigated

with appropriately conditioned SEC columns.

The use of an extraction technique to generate samples for SEC

characterization of OMP impregnated wood may result in samples not

totally representative of the extent of OMP polymerization in the wood.

The GMA co-monomer used in piling 4-5 is believed to form bonds with

the cellulose in the wood, making this polymer more resistant to solvent

extraction (15). THF extracts of pilings 3-1 and 4-5 indicate that

piling 3-1, which used TBTM and MMA precursors had an extractable

polymer content five times greater than piling 4-5, which used the TBTM
and GMA precursors. However, this may be due to differences in the

extractibi 1 ity or solubility of the respective polymers. The second

organotin-release experiment showed that the total tin concentration

released from piling 3-1 exceeded that released from piling 4-5 by

nearly four times (3.8x), lending credance to the suggestion that the

TBTM-GMA polymer is either less soluble in THF, or more tightly bonded

to the wood.

The Tin Research Institute, in the U.K. , has expressed interest in

collaborative work concerning the characterization of the OMP in the

wood pilings. They have offered to run Mossbauer spectra on samples of

OMP impregnated pilings. We hope to begin this collaborative work

soon.

6. Acknowledgments

The work described in this report was supported by the Naval Civil

Engineering Laboratory, Port Hueneme, CA, to whom we extend our thanks.

For valued discussion and suggestions, we are indebted to D. Jackson

and D. M. Anderson of the David Taylor Naval Ship Research and

Development Center, Annapolis, MD.
7. References

1. W. L. Yeager and V. J.Castelli, Antifouling applications of various

tin-containing organometal 1 ic polymers, in Organometal lie Polymers ,

C. E. Carrahar, Jr., J. E. Sheats, and C. U. Pittman, Jr., Eds.,

NY: Academic Press, 1978, 175-180.

2. R. V. Subramanian, J. A. Mendoza and B. K. Garg, Wood preservation

by organotin polymers, Holzforschung 35, 253-259 (1981).

3. K. N. Somasekharan and R. V. Subramanian, Structure, mechanism and

reactivity of organotin carboxyl ate polymers in modification of

polymers, ACS Symp. Ser. 121 , 165-181 (1980).

4. F. E. Brinckman, W. R. Blair, K. L. Jewett, and W. P. Iverson,

Application of a liquid chromatograph coupled with a flameless

atomic absorption detector for speciation of trace organometal 1 ic

compounds, J. Chromatogr. Sci. 15, 493-503 (1977).

5. E. J. Parks, F. E. Brinckman, and W. R. Blair, Application of a

graphite furnace atomic absorption detector automatically coupled

to HPLC for speciation of metal -containing macromolecules, J.

Chromatogr. 185, 563-572 (1979).

6. K. L. Jewett and F. E. Brinckman, Speciation of trace di- and

triorganotins in water by ion exchange HPLC-GFAA, J. Chromatogr.

Sci. 19, 583-593 (1981).

7. E. J. Parks and F. E. Brinckman, Characterization of bioactive

organotin polymers: fractionation and determination of MW by

SEC-GFAA, in Controlled Release of Pesticides and Pharmaceuticals ,

D. H. Lewis, Ed., NY: Plenum Press, 1981, 219-238.
8. E. J. Parks, R. B. Johannesen, and F. E. Brinckman, Advances in

the SEC characterization of organometal 1 ic copolymers and copolymerization: Desorption of charged species by injected dilute acetic

acid. Nat. Bur. Stand. (U.S.) NBSIR 82*2577; 1982 August, 29 p.

9. M. J. Dempsey, Colonisation of anti fouling paints by marine bacteria,

Botanica Marina 26, 185 (1981).

10. E. J. Parks, R. B. Johannesen, and F. E. Brinckman, Characterization

of organometal 1 ic copolymers and copolymerization by size-exclusion

chromatography coupled with trace metal- and mass-sensitive detectors,

J. Chromatogr. 225 , 439 (1983).

11. L. E. Hal las and J. J. Cooney, Tin and tin-resistant microorganisms

in the Chesapeake Bay, Appl. and Envir. Micro. 41, 446 (1981).

12. W. P. Iverson and F. E. Brinckman, Microbial metabolism of heavy

metals, chapter 8 in Water Pol 1 ution Microbiology , Vol. 2,

R. Mitchell, Ed., New York, NY: John Wiley & Sons; 1978, 201-232.

13. A. 0. Summers, S. Silver, Microbial transformations of metals, in

Annual Review of Microbiology , Vol. 32, Palo Alto, CA: Annual

Reviews, Inc.; 1978, 637-672.

14. E. J. Parks, R. B. Johannesen, and F. E. Brinckman, unpublished

data.

15. R. V. Subramanian and B. K. Garg, Recent advances in organotin

polymers, Polym. Plast. Technol. Eng. YL y 81 (1978).
Drain

Figure 1. Block diagram summarizing the HPLC-GFAA system, including

accessory devices. The GFAA spectrophotometer consists of a heated graphite atomizer (HGA) and an atomic absorption spectrophotometer (AA) . In the present work, either the auto-sampler

continuously transferred eluent samples into the graphite

furnace at preset intervals, or batch fractions were collected

during elution for subsequent quantitation of tin.
TOTAL

TIN

(ng)

TOTAL

TIN

(ng)

EXPERIMENT 1

Figure 2

PILING 3-1

AO

35

3Or

25

20

4 eri

5!

\\

\

±6 15 20 25

TIME (hours x 10)

it? A 0

EXPERIMENT 1

PILING 4-5

30

iO 15 20 25 39 35 40

TIME (hours x 10)

3. Graphs are constructed by plotting the total tin concentration in

the piling leachate water versus time. The data from experiment 1 is plotted above. Both pilings show a relatively rapid initial

release of tin, with the concentration reaching a maximum within

2 to 3 days of the start of the experiment, then declining to a more stable level as leaching continued.
TOTAL

TiN

(ng)

TOTAL

TIN

(ng)

Figure 4 5

EXPERIMENT 2

PILING 3-1

30?

i

I

i 2.Q\

104

5

3 4 5 6 7 8

TIME (hours x 100)

EXPERIMENT 2

PILING 4-5

TIME (hours x 100)

5. Graphs constructed as in figures 2 5 3, showing the data from

experiment 2. There is considerable variation in the tin levels at

the beginning of the experiment, perhaps due to varying lates of

water penetration into the pilings and initial surface adsorption

of tin by the leaching jar. As leaching continued the tin level

showed a gradual rise, not unexpected as leached tin was not being

removed (except by surface adsorption) from the jars.
Figure 6.

CATION EXCHANGE

CHROMATOGRAPHY

Calibration

500 ng «a

Bu^Sn Bu Sn

2

2

min

Chromatogram showing GFAA detector responce to 20 microliter sample

aliquots withdrawn from the SCX-HPLC eleuent stream. The dibutyltin

peak in the chromatogram of piling 3-1 represents approximately 5.5%

of the total tin in the sample. The dibutyltin peak suggested in the

piling 4-5 chromatogram by a single GFAA detector responce represents

approximately 3.4% of the total, tin in the sample. HPLC parameters

are listed in table 3.
SIZE EXCLUSION CHROMATOGRAPHY

Figure 7.

THF EXTRACT OF WOOD PILING NO. 3 - 1

3 ° . yStyragel 10 A ( one ) Solvent THF

Eluent THF

Multiple delayed injections of 1.0 % HOAc

I

1 1 1 1 1 1

1 5 10 15 20 25 30

V'r.mL

Size exclusion chromatogram of the THF extract^of piling 3-1. High

molecular weight (MW) polymer is seen in the 10 to 10 MW range.

The arrow subtending the AA baseline indicates the point at which a tin-bearing derivative of HOAC begins to elute. Five hundred microliter volumes of 1.0% HOAC were injected 10,16,22 and 33 minutes after

the initial sample injection.
SIZE EXCLUSION CHROMATOGRAPHY

Figure 8.

THF EXTRACT OF WOOD PILING NO. 4 - 5

3

o pStyragel 10 A ( one ) Solvent THF

Eluent THF

Multiple delayed injections of 1.0 % HOAc

T~

5 —i

10 —i

15

“i

20 25

Vp , m L

Size exclusion chromatgrgam of the THF extract of piling 4-5. Note

the absence of high MW polymer in comparison to figure 7. Injections

of 1.0% H0AC followed the sample injection by 8,12, 16, and 20

minutes, with the arrow subtending the AA baseline indicating the

point at which a tin-bearing derivative of HOAC begins to elute.
NBS-114A (REV. 2-80

U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET (See instructions)

4. TITLE AND SUBTITLE

1. PUBLICATION OR

REPORT NO.

NBSIR 83-2733

2. Performing Organ. Report NoJ 3. Publication Date

July 1983

Characterization of Leaching Dynamics and Identification of Leached Species

from OMP Impregnated Wood Pilings

5. AUTHOR(S)

W.R. Blair, E.J. Parks, and F . E . Brinckman

6. PERFORMING ORGANIZATION (If joint or other than NBS, see instructions) 7. Contract/Grant No. N68305 82MP20019

national bureau of standards _

DEPARTMENT OF COMMERCE 8 WASHINGTON, D.C. 20234

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City. State. ZIP)

. Type of Report & Period Covered

final

Naval Civil Engineering Laboratory

Port Hueneme, CA 93043

10. SUPPLEMENTARY NOTES

| | Document describes a computer program; SF-185, FIPS Software Summary, is attached.

11. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here)

Organometallic polymers (omp) are becoming an increasingly important class

of compounds finding application in marine environments as anti-fouling and

preservative agents. To provide accurate estimates of reliability in service and

service life, new analytical methods are needed for the identification and measurement

of the toxic species being delivered by the OMP. This report is concerned with the

following: identification of parent tin species; identification of species leached

from OMP impregnated wood pilings; and preliminary determination of the rate of tin

release from OMP impregnated pilings. Additionally, the influence of microbiological

activities on the leachate is considered in assessing the effectiveness and ultimate

fate of the toxic species responsible for the anti-fouling and preservative properties

of the OMP formulation. Data from leach rate measurment experiments are presented,

along with chromatograms providing speciation data on parent and leachate tin compound'

,

discussion of areas for continued research are presented.

12. KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolons)

atomic absorption spectrophotometry; cation exchange chromatography; high pressure

liquid chromatography; in situ polymerization; leaching; organometallic polymers;

size exclusion chromatography; tributyltin

13. AVAILABILITY 14. NO. OF

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