Potential Organic Contamination Associated with Commercially

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Downloaded by UNIV OF CALIFORNIA SAN DIEGO on January 24, 2017 | http://pubs.acs.org Publication Date: December 15, 1986 | doi: 10.1021/ba-1987-0214.ch011

Potential Organic Contamination Associated with Commercially Available Polymeric Sorbents Contaminant Sources, Types, and Amounts Gary Hunt Environmental Research and Technology, Inc., Concord, MA 01742 Polymeric sorbents are used extensively in the isolation and preconcentration of semivolatile trace organics from aquatic matrices. These synthetic materials contain measurable or significant quantities of one or more of the following types of chemical contamination: (1) residual monomers, (2) artifacts of the polymer synthetic pathway, and (3) chemical preservatives used to inhibit chemical or biological degradation. This chapter provides some insight into the chemistry of a number of commonly used polymeric sorbents. Particular focus is placed on the chemical identification of solvent-extractable semivolatile organic contaminants typically associated with each of the following types of polymeric sorbents as received from the manufacturer: Amberlite XAD resins, Ambersorb XE resins, and polyurethane foam.

PoLYMERIC SORBENTS are frequently used in environmental analytical schemes for the isolation and/or preconcentration of trace organic contaminants from air and water matrices. Commercially manufactured polymeric sorbents such as Amberlite X A D resins, Ambersorb X E resins, Tenax (diphenyl-p-phenylene oxide), and polyurethane foam (PUF) have been used extensively for the collection of trace organic contaminants from ambient air, process streams (i.e., flue gas), and a variety of aquatic matrices including industrial effluents, ground water, surface water, and potable water supplies. Currently, these materials 0065-2393/87/0214/0247$06.00/0 ® 1987 American Chemical Society

American Chemical Society, Library 1155 16th St. N.W. Suffet and Malaiyandi; Organic in Water Washington, D Pollutants & 20036 Advances in Chemistry; American Chemical Society: Washington, DC, 1986.


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ORGANIC POLLUTANTS IN WATER

are used extensively in the preconcentration of trace organics from waters for eventual use in biological testing. The use of solid sorbents in this manner permits concentration levels more compatible with current state-of-the-art biological testing procedures. Prior to the use of polymeric sorbents in actual isolation schemes, however, users should focus on a number of quality assurance issues including the impact of sorbent contaminants on subsequent biological testing. F o r instance, the presence of suspected carcinogens in sample extracts arising from the sorbent itself may bias the results of an eventual biological assay procedure. The majority of these synthetic materials as received f r o m the manufacturer can be expected to contain measurable or perhaps significant quantities of one or more of the following types of chemical contamination: (1) residual monomers, (2) artifacts of the polymer synthetic process (e.g., starting materials, catalysts, and byproducts), and (3) chemical preservatives to inhibit chemical or biological degradation. F o r these reasons, all sorbent materials should undergo rigorous cleanup procedures p r i o r to use. Numerous sorbent preparation procedures that are capable of reducing contamination to levels compatible with the eventual end use of the sorbent are available in the literature. Users are cautioned, however, that because of the significant contamination often encountered, any cleanup procedure can at best only minimize these contaminants and oftentimes leave measurable quantities of organics characteristic of the respective polymer. In addition, although numerous cleanup procedures are available for establishing resin quality, the subsequent storage and handling of these materials can promote the reappearance of contamination. Users are, therefore, urged to familiarize themselves with the chemical nature of polymeric sorbent contaminants as well as proper cleanup, storage, and handling procedures. This chapter provides some insight into the chemistry of a number of commonly used polymeric sorbents. Particular focus is placed on the chemical identification of contaminants typically associated with each of the following types of polymeric sorbents: Amberlite X A D resins, Ambersorb X E resins, and P U F . Emphasis is placed on the chemical speciation of solvent-extractable organic contaminants present in a number of these sorbents as received f r o m the manufacturer. Both qualitative and quantitative data on a micrograms-per-gram (parts-per-million) basis are p r o v i d e d as determined b y c o m b i n e d gas chromatography-mass spectrometry ( G C - M S ) .

Experimental Reagents. All reagents used in experimental procedures were of the highest grade commercially available. Methylene chloride, hexane, and ethyl ether used

Suffet and Malaiyandi; Organic Pollutants in Water Advances in Chemistry; American Chemical Society: Washington, DC, 1986.

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in the sorbent preparation procedure were distilled in glass quality manufactured by Burdick and Jackson. dio-Anthracene, which served as an internal standard in all GC-MS analyses, was obtained from KOR Isotopes. Amberlite XAD-2 and XAD-4 and Ambersorb XE-340 and XE-348 resins were obtained through the courtesy of Rohm & Haas. Representative lots of each of the four resins were provided. The PUF was purchased from Flexible Foam Products. The foam (type 1636) was purchased in sheets 4 ft X 4 ft and 3 in. in depth. Sample Preparation. AMBERLITE XAD RESINS. Two lots of Amberlite XAD-2 resin and one lot of Amberlite XAD-4 resin were prepared for analysis. Aliquots of each resin sample (5-10 g) were extracted for approximately 24 h in a continuous Soxhlet apparatus containing methylene chloride . Extracts were reduced to 2.0 mL by employing a rotary evaporator operating under reduced pressure. The use of a rotary evaporative concentration technique under reduced pressure will significantly reduce concentrations of volatile organics and selected lower boiling semivolatile species contained in the solvent extract. Hence, results provided for both the Amberlite and Ambersorb sorbent series more accurately represent the semivolatile contaminant chemistry characteristic of these sorbents. The volatile organic data reported here thus represents minimum values. Further details on the sample preparation procedures were reported previously (1). 1

AMBERSORB X E RESINS. Two lots of Ambersorb XE-340 and one lot of Ambersorb XE-348 were prepared for analysis. The sample size and preparation procedures were identical to those employed for the Amberlite XAD series. Further details pertinent to these analyses are contained in a previous publication (2). PUF. Sorbent plugs were removed from the 4- X 4-ft sheets by employing a 4-in. template. Two such plugs were randomly removed, each measuring 4 in. in diameter and 3 in. in depth. Plug weights were taken to the nearest 0.1 g. One plug was extracted overnight (ca. 8 h) in a Soxhlet extractor containing an ethyl ether/hexane (5/95) solvent system. The second plug was extracted for the same period with methylene chloride. A third Soxhlet extractor designated as the procedural blank contained only the ethyl ether/hexane (5/95) solvent system. Upon completion of the extraction cycle, all extracts were reduced in volume to 2.0 mL in a Kuderna-Danish evaporative concentrator. Gas Chromatography-Flame Ionization Detection and Gas Chromatography-Mass Spectrometry. AMBERLITE XAD RESINS. Extracts were analyzed for total chromatographable organics (TCO) with a gas chromatograph fitted with a flame ionization detector (GC-FID). The TCO data provided a quantitative distribution of organics boiling between 100 and 300 °C and divided them into discrete temperature intervals. Each of five boiling point ranges was established on the basis of the analysis of a C 7 - Q 7 n-alkane mixture representing a temperature distribution of 100-300 °C. Quantitative values in units of micro-

Methylene chloride was selected primarily on the basis of the following criteria: (1) It is commonly referred to as the universal solvent or the one used most frequently in the extraction of semivolatile organics sorbed on polymeric sorbent media. Hence, the contaminant chemistry associated with this solvent system would be of the most use to resin users. (2) The physical and chemical properties of methylene chloride make it ideally suited for the extraction of semivolatile organics sorbed on polymeric sorbent media.

1



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grams per gram (parts per million) were established by comparison with an n-decane standard. All GC-FID chromatographic analyses were performed with a Tracor 560 gas chromatograph fitted with a dual FID unit. A summary of pertinent instrumental operating conditions is contained in a previous publication (2). All GC-MS analyses were performed on a Hewlett-Packard 5985 quadrupole mass spectrometer. Pertinent chromatographic and mass spectral operating parameters are described elsewhere (2). Spectra were collected and recorded in the total ion mode. Individual component spectra were manually compared with U.S. Environmental Protection Agency-National Institutes of Health (USEPA-NIH) library spectra to provide component identifications. All quantitative data were provided as referenced to the dio-anthracene internal standard. AMBERSORB X E RESINS. All instrumental analyses were identical to those employed in the analysis of the Amberlite XAD resins as described previously (2). PUF. Each of the three 2.0-mL PUF extracts was subjected to GC-MS analyses. All analyses were conducted with a Finnigan OWA 1020 GC-MS system fitted with an SE-54 fused-silica capillary column. All spectra were collected in the total ion mode. Component spectra, both raw and background subtracted, were manually compared against USEPA-NIH library spectra to permit component identifications. Quantitative data were again provided by using dio-anthracene as the internal standard.

Results and Discussion Amberlite X A D Resins. Amberlite X A D resins are synthetic adsorbents structurally composed of a styrene-divinylbenzene copolymer. Because of the polymeric production process, users are cautioned that these resins do contain significant quantities of preservatives and monomers as received from the manufacturer, Rohm and Haas (3, 4). Results of the gas chromatographic analyses for each of the Amberlite XAD-polymeric sorbents are shown in Figure 1. Extractable organic concentrations in micrograms per gram (parts per million) are depicted for each of five boiling point intervals spanning from 100 to 300 °C. As shown, results for each of the two Amberlite sorbents are significantly higher than the corresponding values for each of the Ambersorb resins. Further analyses of representative extracts of each of the Amberlite resins employing G C - M S indicated the presence of significant concentrations of a variety of aromatic hydrocarbons, including alkylated derivatives of benzene, styrene, naphthalene, and biphenyl. A more comprehensive listing of these contaminants, including their approximate concentrations in the sorbent matrix, is provided in Table I. Although results for the two Ambersorb resins are in good qualitative agreement, the contaminant concentrations are consistently much higher for the Amberlite X A D - 4 resin. This trend is directly attributable to the higher surface area of 725 m /g associated with the XAD-4 2



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Figure 1. C omparison of extractable organics in four commercially avaifoble synthetic adsorbents. sorbent beads as opposed to the 300-mVg area associated with the X A D - 2 polymer (3, 4). At times, these properties have adversely affected the use of the Amberlite X A D - 4 resin in environmental sampling schemes (5, 6). In both instances, the contaminants listed in Table I show a marked structural similarity to the characteristic parent structure of the Amberlite polymer repeating unit, as shown in Chart I. The predominance of benzene, styrene, naphthalene, and biphenyl derivatives suggests that the extractable contaminants are either residuals f r o m the resin manufacturing process (e.g., starting materials or secondary byproducts) or artifacts f r o m the degradation of the polymer itself during storage and handling, subsequent to the manufacturing process. In either case, prospective resin users are cautioned that X A D resins must undergo rigorous cleanup prior to use in actual environmental sampling regimes. The most widely accepted cleanup procedures are


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Table I. Chemical Characterization and Quantitation of Organic Contaminants Extracted from Amberlite XAD Resins Concentration


Compound Name Methylbenzene (toluene) Dimethylbenzene isomer Diethylbenzene isomer 4-Ethyl-l,2-dimethylbenzene l-Ethyl-2,3-dimethylbenzene Triethylbenzene isomer Ethenylbenzene (styrene) 1 -E thenyl-4-ethylbenzene 1 -E thenyl-3-methylbenzene 1 -Ethenyl-3,5-dimethylbenzene 2-E thenyl-1,3-dimethylbenzene 1,4- or 1,3-Diethenylbenzene 1- or 3-Methylindene Naphthalene 1- or 2-Ethylnaphthalene 1- or 2-Methylnaphthalene l,l'-Biphenyl 2- or 3-Methyl-l,l'-biphenyl Ι,Γ-Biphenyl, dimethyl isomer 1,1'-Methylenebis[benzene] 1, Γ -Ε thyhdenebis [benzene] l,r-(l,2-Ethenediyl)bis[benzene] l,l-Bis(p-ethylphenyl)ethane

XAD-2 nd nd 102 d d d 19 320 15 d d 45 m 470 d 19 69 d d d 130 d 26

XAD-4 10000 53 nd d 490 nd d 5700 1800 nd nd 5960 3470 6870 710 1020 1300 90 nd nd 55 67 nd

N O T E : d denotes component was detected but not quantitated; nd denotes component was not identified in the lots examined (< 5 Mg/g). S O U R C E : Adapted from reference 2.

those employing sequential solvent extraction i n a Soxhlet apparatus (7, 8). As shown i n Figure 2, a continuous extraction scheme employing a sequence of water, methanol, and methylene chloride can virtually eliminate chromatographable organic extractables associated with the sorbent matrix. Amberlite resin contamination is qualitatively consistent f r o m lot to lot as received f r o m the manufacturer. This finding is perhaps attributable to the patented synthetic process employed b y R o h m and Haas in the manufacture of the Amberlite resin product line. Ambersorb Resins. Chromatographable residues attributable to each of the Ambersorb resins, X E - 3 4 0 and X E - 3 4 8 , as shown i n Figure 1, are significantly lower than the values reported for each of the Amberlite resins. As shown in Figure 3, the majority of the components isolated f r o m the Ambersorb X E - 3 4 0 resin are readily classified as poly cyclic aromatic hydrocarbons. (These are believed to be associated


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CH=CH


I

- C H

2

- C H -

C H - CH 2

2

CH -CH2

BIPHENYL

Chart I. Comparison of XAD-2 polymer repeating unit with parent structures of typical contaminant species. (Reproduced with permission from reference 1. Copyright 1980 Marcel Dekker.) with the sorbent manufacturing process.) No discernible constituents were noted in the Ambersorb XE-348 extract (not shown) which closely approximated the accompanying laboratory method blank. Both Ambersorb XE-340 and XE-348 are members of a carbonaceous polymer product line currently manufactured exclusively by Rohm and Haas. The chemical composition of these sorbents is generally regarded to be intermediate between that ascribed to either activated carbon or a purely polymeric sorbent (9,10).


254

ORGANIC POLLUTANTS IN WATER Ι,ΟΟΟι

UNCLEANED

XAD-2

CLEANED

XAO-2

Organic Levels


(/ug/g of resin) 100 (Quantified with G C - F I D Relative to n-Decane)

•Oh

100-140

140-180

180-220

220-260

1

260-300'

Boiling Point Distribution (°C)

Figure 2. Comparison of extractable organic (CH2CI2) and cleaned XAD-2 resin.

levels in uncleaned

The patented Ambersorb manufacturing process relies on the car bonization of a macroreticular styrene-divinylbenzene-based copolymer (21). At the outset, the copolymer starting materials are sulfonated to render them infusible. The actual production process proceeds via a partial pyrolysis of the starting polymer at a prescribed temperature. When pyrolysis proceeds at a relatively low temperature (300-400 °C), the polymeric structure is retained and subsequently superimposed on the carbonaceous starting material. This process is consistent with that used in the actual manufacture of Ambersorb XE-340 resin. The fusedring aromatic hydrocarbons noted during G C - M S analysis of the Am bersorb XE-340 extractable fraction may have been formed during this carbonization process. Perhaps they were formed via a free radical condensation involving the monomelic precursors (e.g., benzene and toluene) known to be associated with styrene-divinylbenzene copolymers. In fact, experimental data collected during this carbon ization process have indicated that toluene and styrene account for the majority of the volatile hydrocarbon fraction released during the initial stages of the carbonization process (11). The actual Ambersorb synthetic process is assumed to proceed from an original styrenedivinylbenzene polymer backbone via a series of free radical combina tions and electrolytic reactions. The postulated chemical structures for Suffet and Malaiyandi; Organic Pollutants in Water Advances in Chemistry; American Chemical Society: Washington, DC, 1986.

Suffet and Malaiyandi; Organic Pollutants in Water Advances in Chemistry; American Chemical Society: Washington, DC, 1986. II

y

Figure 3. Total ion chromatogram of extractable organics in a typical lot of Ambersorb XE-340 resin (SP-2100,10-m capillary column, temperature program 50(2)-250 at 5 °C/min, 1.0-μΐ, splitless injection), 1, naphthalene; 2,1- or 2-methylnaphthalene; 3, biphenyl; 4 Ι,Γ-biphenyl, 2- or 3-methyl; 5, fluorene; 6, anthracene-phenanthrene; 7,1- or 2-phenylnaphthalene; 8, pyrene; 9, fluoranthene; 10, terphenyl isomer; 11, benzo[b]naphthothiophene isomer; 12, binaphthalene isomer; 13, benzofluoranthene isomer. (Reproduced from reference 2. Copyright 1982 American Chemical Society.)

Minutes

9


256


some of these end products resulting f r o m treatment of the starting copolymer at a variety of elevated temperatures under pyrolysis conditions ( N ) are shown in Scheme I. [Note the increased condensation and aromaticity of the end product in proceeding f r o m Structure I to Structure III. Structure I is believed to represent the actual chemical structure of an Ambersorb X E - 3 4 0 resin (21).] Similar reaction trends could account for the fused-ring aromatics isolated f r o m the Ambersorb X E - 3 4 0 product. Conversely, Ambersorb X E - 3 4 8 , which is produced v i a pyrolysis at a much higher temperature of 700 °C, shows no evidence of the presence of these same lower molecular weight fused-ring aromatics. A t these higher temperatures, the polymeric properties of the sorbent are diminished, and the end product more closely approximates the properties of a carbonaceous sorbent.


2

P U F . Flexible P U F constitutes a generic class of polymeric sorbents that have been used extensively in recent years in a variety of environmental sampling applications. P U F , unlike other polymeric sorbents, which are generally manufactured b y a single patented process, can be synthesized v i a any one of a number of patented processes. The most c o m m o n synthetic pathways employ organic isocyanates (aliphatic or aromatic) and a polyol as starting materials, as shown in Scheme II. In addition, a number of chemical additives (see box) are generally introduced during the synthetic process to impart particular chemical or physical properties to the final foam product, as shown in Scheme III (22, 23). H i g h molecular weight halogenated organics, for example,

Ingredients Commonly Used in the PUF Manufacturing Industry Foam Stabilizers-Surface Diisocyanates Active Agents 2,4-Toluene diisocyanate Silicone oils 2,6-Toluene diisocyanate 4,4'-Diphenylmethane diisocyanate Silicone-glycol copolymers Hexamethylene diisocyanate Cross-Linking Agents Blowing Agents ( tnols-polyethers-alkanokmines) (halogenated alkanes-water) Glycerol Triethanolamine Trichlorofluoromethane Pentaerythritol Methylene chloride Fire Retardants Tris(2-chloroethyl) phosphate Tris(2,3-dibromopropyl) phosphate Diammonium phosphate Antimony oxides

Catalyst(s) (tertiary amines) Triethylenediamine Triethylamine Dimethylpiperazine N,N-Dimethylcyclohexylamine

S o i ' R C E : Adapted from references 12 and 13.


Suffet and Malaiyandi; Organic Pollutants in Water Advances in Chemistry; American Chemical Society: Washington, DC, 1986. Scheme 1. Chemical structures postulated for Ambersorb-type carbonaceous adsorbents ( reaction products resulting from the thermal treatment of a styrene-divinylbenzene copolymer).



Scheme IL The synthesis of PUF: typical reaction sequence involving an aromatic isocyanate (TDI) and a


Suffet and Malaiyandi; Organic Pollutants in Water Advances in Chemistry; American Chemical Society: Washington, DC, 1986. 2

POLYURETHANE FOAM OCNHRNHCOCR'O

CROSS-LINKING AGENT

S U R F A C E ACTIVE AGENTS

Scheme III. PUF manufacturing process: general synthetic pathway.

R'(OH)

R(NCO) 2

POLYOL

ISOCYANATE

FLAME RETARDANT

BLOWING A G E N T

CATALYST



260


are typically added to impart fire-retardant properties to the foam (13). Some of the more commonly used chemical ingredients are listed in the box. Thus, P U F products can be expected to contain a number of these chemical additives as well as other synthetic artifacts as received from the supplier. Furthermore, the quality of flexible foam products w i l l vary markedly f r o m supplier to supplier as well as f r o m manufacturer to manufacturer. P U F , unlike other polymeric sorbents, tends to be a nonhomogeneous product containing a number of additives and artifacts in variable quantities f r o m lot to lot. O u r experience, however, indicates that these contaminants can be sufficiently reduced to permit trace organic analysis b y employing a sequential solvent extraction procedure in conjunction with stringent quality control criteria prior to actual use. This observation is consistent with the experience of other investigators who have used flexible foams extensively in analytical environments. A reconstructed ion chromatogram ( G C - M S ) containing extractable contaminants isolated f r o m a typical lot of foam is shown in Figure 4. T h e qualitative composition of the extractable contaminants was provided b y G C - M S . Contaminant profiles were identical for each of the two solvent systems employed, methylene chloride (100$) and ethyl ether/hexane (5/95). The contaminant chemistry shown here and again in Figure 5 in several instances is consistent with the manufacturing process data shown in the box, most notably the presence of residual toluene diisocyanate (starting materials, see Scheme II) and an aliphatic amine (possible reaction catalyst). Because of the w i d e diversity in P U F manufacturing processes and likely contaminant chemistry, users are cautioned that sorbent quality control is more critical than with other synthetic polymers such as the Amberlite X A D series. E v e r y effort should be made to procure P U F products consistently f r o m the same manufacturer, preferably in each instance f r o m the same production lot. Moreover, because of inconsistencies in manufacturing practices, first-time foam users should solicit the advice of other satisfied and experienced users in the selection of a sorbent supplier.

Conclusions Chemical analyses of a variety of commercially available synthetic adsorbents indicate that significant quantities of extractable organics are present in these products as received f r o m the manufacturer. The majority of these contaminants can be classified as either residual monomers, synthetic artifacts, or preservatives peculiar to the manufacturing process, packaging, storage, and handling of the sorbent itself. The manufacturing process is alleged to be the most significant contributor to the levels of extractable organics present in these materials.


Suffet and Malaiyandi; Organic Pollutants in Water Advances in Chemistry; American Chemical Society: Washington, DC, 1986. 152

200 5:10

400 10;2Θ

p-

391

468

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507

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Γ

592

ψ

737

800 20:40

[

8Θ6 902

D^-anthracene (IS) (50 ug/ml; 25/i/g)

1000 25:50

985

1047

1133 1200 31:00

1400 SCAN 36:10 TIME

Figure 4. Extractable organic profile (ethyl ether/hexane, 5/95) of a random lot of flexible PUF: reconstructed ion chromatograms (GC-MS). A, solvent extract; B, Soxhlet bknk. Component identification (scan number, component): 232, phenol; 391, hexanoic acid, 2-ethyl; 490, 2,4- or 2,6-toluene diisocyanate (TOI), 507, 2-propanamine, 2-methyl; 592, phenol, 2,6-bis-(l,l-dimethylethyl)-4-methyl; 696, chloroctane (isomer); 737, anthracene-am (internal standard); 1047, isooctane, ethenyloxy. Continued on next page.

RIC

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2. β bw ( 11 . -0ifnelhyi#1hyl>-4 methyl (Commercial AntioxKtem)

I 195

11,1.1 11

^Θ3 ,l...ill|ill,..,llijlii l

j,l,U,

Figure 5. Mass spectral data: selected organic extractables (methylene chlonde) isolated from a random lot of PUF.


264


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Figure 5. Continued. Amberlite X A D - 2 and X A D - 4 resins, for example, contain significant quantities of alkyl derivatives of benzene, styrene, naphthalene, and biphenyl as received f r o m the supplier. P U F products, on the other hand, generally contain numerous contaminants peculiar to one of the several patented commercial manufacturing processes. These include, but are not limited to, the following classes of chemical contaminants: isocyanate derivatives (e.g., toluene diisocyanates), alkyl amines, aliphatic acids, and brominated aromatics (e.g., fire retardants). The native sorbent contamination should be reduced significantly prior to use of the collection media in actual aquatic sampling schemes. In practice, these materials cannot be removed entirely but can only be lowered sufficiently so as to permit subsequent analysis and to achieve the requisite detection limits. In all instances, users of polymer-type sorbents are urged to familiarize themselves with sorbent contaminant chemistry in order to recognize spurious data points arising from the use of improperly cleaned or mishandled resins. Furthermore, rigorous quality control measures, including field blanks, and sorbent contamination tolerance criteria should be instituted to both curtail and permit recognition of contamination arising from sorbent use. W e have found that rigorous sorbent pretreatment procedures (e.g., Soxhlet extraction and thermal desorption) in concert with a well-established quality control program w i l l successfully control potential contamination effects arising from the sample collection media. Furthermore, a well-executed quality control program w i l l permit identification of spurious data points attributable to media contamination when and if they do occur.


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Literature Cited 1. 2. 3. 4. 5.


6. 7. 8. 9. 10. 11. 12. 13.

Hunt, G. T.; Pangaro, N.; Zelenski, S. G. Anal. Lett. 1980, 13(A7), 521. Hunt, G. T.; Pangaro, N. Anal. Chem. 1982, 54, 369. Amberlite XAD-2 Technical Bulletin; Rohm and Haas: Philadelphia, 1978. Amberlite XAD-4 Technical Bulletin; Rohm and Haas: Philadelphia, 1978. Adam, J.; Menzies, K.; Levin, P. EPA Report No. 600/7-77-044, Arthur D. Little, Inc., 1977. Thurman, Ε. M.; Aiken, G. R.; Malcolm, R. L. Proceedings of the Fourth Conference on Sensing of Environmental Pollutants; New Orleans, LA, 1978. Lentzen, D. E. et al. IERL/RTP Procedures Manual: Level 1 Environmental Assessment; Environmental Protection Agency. U.S. Government Printing Office: Washington, DC, 1978; EPA-600/7-78-201 Junk, G. A. et al. J. Chromatogr. 1974, 99, 745. Ambersorb Carbonaceous Adsorbents; Rohm and Haas: Philadelphia. Neely, J. W. Proceedings Division of Environmental Chemistry, American Chemical Society National Meeting, Miami, FL; American Chemical Society: Washington, DC, 1978; paper 72, pp 204-205. Carbonaceous Adsorbents for the Treatment of Ground and Surface Waters; Neely, J. F.; Isacoff, E. G., Eds.; Marcel Dekker: New York, 1983; pp 41-78. Edwards, G. D.; Rice, D. M.; Soulen, R. L. U.S. Patent 3 297 597, 1967. Kirk-Othmer Encyclopedia of Chemical Technology; John Wiley: New York, 1981; 3rd ed., Vol. 23.

R E C E I V E D for review August 14, 1985. A C C E P T E D January 28, 1986.


Potential Organic Contamination Associated with Commercially

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