369
Anal. Chem. 1982, 5 4 , 369-372 (16) Dawson, J. S. J . Geophys. Res. 1977, 82, 9125-3133. (17) Wilson, J. C.; McMurray, P. H., Mechanlcal Engineering Department, University of Minnesota, Minneapolis, MN, prlvate communication, lQ80. (18) Hoell, J. M., NASA Larigiey Research Center, Hampton, VA, private
(20)
Braman R. S.; Shelley, T. J. "Gaseous and Particulate Ammonia and Nitric Acid Concentrations-Columbus, Ohio, Area, Summer 1980"; EPA 600/7-80-17Q; U. S. Environmental Protection Agency: Research Triangle Park, NC, 1980.
communication. - -. .....-. ..__ .. -...
(IQ)
McClenny, W. A.; Beninett, C. A., Jr.
Atmtw. Envkon. 1880, 74,
641-645.
RECEIVED for review May 20,1981. Accepted October 9,1981.
Potential contamination from the Use of Synthetic Adsorbents in Air Sampling Procedures Gary Hunt* and Nlchlolas Pangaro Laboratory Analysis Department, GCA/Technology Division, 2 13 Burlington Road, Bedford, Massachuseits 0 1730
The qualitative and qurintltatlve characterization of the residual organics in each of four commercially available solid sorbents Is reported. The structures of the contaminants are verlfied by gas chromatagraphy/mass spectrometry (GC/MS), and suggested sources for the contaminants are discussed. High artifact levels inclluding alkyl derivatives of benzene, styrene, naphthalene, and biphenyl are characteristic of the two Amberiite resins studied. Inadequate resin cleanup procedures can result In significant concentrations of these materials appearing In actual resin sample extracts. Polycyclic aromatics are typical of the Ambeirsorb XE-340 resin. Preparation procedures for synthetic adsorbents including data on solvent extraction techniques prior to use In air Sampllng schemes are discussed. Artifact levels (pg/g) for lots of both prepared and unprepared resinr are presented for comparison.
In recent years there has been an increased demand to optimize analytical sensitivity in environmental sampling schemes. This has often been prompted by the need to assess the health effects of tram levels of organic compounds present in aqueous and gaseous systems. For such purposes, the majority of techniques in use today emplloy a concentration or enrichment of organics on one or more solid adsorbents to facilitate the collection of low level organics from water (1-11) and air (12-21) matrices. The majority of solid sorbents in routine use are synthetic polymers that contain significant levels of manufacturer's artifacts such as preservatives and/or monomeric materials (22, 23). Prior to use, these materials must be removed to minimize sample contaniination during subsequent analysefl. This is best accomplished by employing one of a series of rigorous cleanup procedures. However, due to the nature and magnitude of these residues, any cleanulp procedure can at best only minimize the extractable materials, leaving detectable quantities of a variety of organic constituents. Maintaining an optimuim contaminant free condition is dependent, as well, upon suitable storage procedures (24) free from variations in temperature (4, 2 1 ) . Since the eventual disposition of each resin may vary depending upon desired organic speciation and dletection limits, these residual materials may pose a significant hindrance in1 the identification and quantitation of environmental extracts Our investigations have included a complete chemical characterization of ex0003-2700/82/0354-0389801.25/0
tractable organics present in a series of commercially available synthetic adsorbents. Random lots of four separate resins including two polymeric Amberlite XAD resins and two carbonaceous Ambersorb adsorbents were investigated. Extractable organics were characterized and quantitated utilizing capillary GC/MS. Available adsorbent cleanup procedures will be discussed and data presented on the utility of a typical sequential solvent extraction procedure in preparing uncleaned resins for use in air sampling schemes.
EXPERIMENTAL SECTION Reagents. All reagents utilized in experimental procedures were of the highest grade commercially available. Solvents used in all extractions were Burdick and Jackson distilled-in-glass. Alkane standards used in chromatographic quantitations were obtained from Aldrich Chemical (Metuchen, NJ). Anthracene-dlo used in all GC/MS confirmatory procedures was obtained from KOR Isotopes, Cambridge, MA. All resins utilized in these analyses were obtained through the courtesy of Rohm and Haas Co., Philadelphia, PA. These included several representative lots of each of four resins. Instrumentation/Quantitative Measurements. Boiling point distributions of organics were assessed utilizing gas chromatography. Boiling point ranges were assigned to each sample by comparison to a C7-CI7n-alkane mixture representing a temperature distribution of 100-300 "C. Quantitative data were established by comparison to an n-decane standard. All chromatographic analyses were obtained on a Tracor 560 equipped with a dual FID. Column conditions included the following: 10% SP 2100 on 100/120 Supelcoport (6 f t glass X 2 mm i.d.). A temperature program from 50 to 250 "C with a 5 min hold at start and finish. Carrier flow was 20 mL/min, inlet temperature 250 "C, and detector 300 "C. All GC/MS analyses were performed on a Hewlett-Packard 5985 quadrupole mass spectrometer. Chromatographic separations were accomplished by using a 10-m SP 2100 glass capillary column programmed from 50 to 250 "C at 5 "C/min. Between 0.5 and 1.0 gL injection volumes were made in both split and splitless modes. Mass spectrometer operating parameters were the following: scan time, 2.5 8, multiplier voltage, 2400 V, electron energy, 70 eV, and inlet temperature, 275 "C. Total ion chromatograms were collected and individual component spectra were manually compared with computerized library mass spectra to provide qualitative identifications. All quantitativemeasurements were made relative to the anthracene-d,, spike. Sample Preparation. Four types of commercially available synthetic resins were analyzed for typical organic impurities as received from the manufacturer. Two lots of Amberlite XAD-2, 0 IQ82 American Chemical Soclety
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ANALYTICAL CHEMISTRY, VOL. 54, NO. 3, MARCH 1982
Table I. Physical Properties of Synthetic Adsorbents (22,23,26)
resin
chemical structure
polarity
Amberlite XAD-2
copolymer of styrene-divinylbenzene copolymer of styrene-divinylbenzene carbonaceous composition similar to polymeric adsorbents carbonaceous composition similar to activated carbon
nonpolar hydrophobic nonpolar hydrophobic nonpolar hydrophobic polar hydrophilic
Amberlite XAD-4 Ambersorb 340 Ambersorb 348
Table 11. Comparison of Extractable Organics (CH,Cl,) in Four Synthetic Adsorbents
adsorbent
1
SP-2100
surface area, m2/g 300
pore volume, pore cm3/g diameter, A 0.854
90
725
1.145
40
400
0.34
500
0.58
100-300 (69%) 100-300 (51%)
10 METER C A P I L L l R Y COLUMN TEMPERClTURE P R O G R A M 50121-250 A T 5'C/m#n 1.0 L L SPLITLESS INJECTION
total extractable organics (Mg/g)" by boiling point region 10014018Q220- 260140°C 180°C 220°C 260°C 300°C
XAD-2 1.0 180 640 72 99 XAD-4 9500 120 9300 550 47 2.0 0.4 2.7 XE-340 9.1 1.3 XE-348 7.8
