Environmental Applications m
Quadrupole mass spectrometers currently enjoy widespread analytical usage that has been estimated a t more than 80%of the total mass spectrometer market ( I ) . The availability of computer-supported quadrupole mass spectrometry (QMS), ita high intrinsic sensitivity, and its compatibility with gas chromatographs led to its adoption
The complexity of environmental samples (as many as 50-100 organic components, a t widely varying concentrations, in diverse sample matrices), the intrinsic shortcomings of QMS when used alone, and the regulatory significance of environmental analytical results have led to a cautious targetlist approach to organic environmental analysis (2). This approach requires target-list-type validated protocols, reference spectra, and authentic standards. Although the current number of standards in the EPA standards repository is about 1500,and the CIS-NIHEPA mass spectral database contains about 44,205 reference spectra, the number of known chemicals is now about 9 X 106 and is reported to be increasing a t a rate faster than exponential (see Figure 1). The situation is not quite as complex in elemental analysis, but the heavy analysis loads inherent to routine mon-
in the late 1970s by the U.S.Environmental Protection Agency (EPA) as its primary monitoring tool for trace organics. In contrast, the predominant methods for elemental environmental analysis thus far have been flame or graphite furnace atomic absorption spectrometry (GF-AAS) and inductively coupled plasma atomic emission spectrometry (ICP-AES).
itoring and the very high sensitivity usually required cannot be simultaneously accommodated by either of the two commonly used methods. Additionally, the complex nature of environmental samples often leads to considerable problems with spectral interferences in ICP-AES and to chemical or physical interferences in flame AAS or GF-AAS.
Donald F. Gulka, L. Domeliy Betowski, Thomas A. Hinners, and Edward M. Heiihmar
U.?. Environmental Protection Agency Office of Research and Development Las Vegas, Nev. 89193-3478
Richard Mus Chemistry Department
University of Nevada at Las Vegas Las Vegas, Nev. 89154
John M. Henshaw Lockheed-EMSCo Las Vegas. Nev. 89919
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-
. .jure
1. Rate of increase in known chemicals. (Adapted wlth permission from Oppomnrifiesin Chmishy, @ 1985 by the National Academy 01
Sciences.)
0003-2700188/0360-454A/$01.50/0 @ 1988 American Chemical Society
of Hyphenated Quadrupole
Clearly, new approaches to environmental monitoring are required that can maximize the amount of sample information obtained in a cost-effective fashion. These new approaches should more efficiently separate contaminant analytes from interferences and should provide more analyte information. Powerful computer software is required to collect, refine, and interpret the additional analytical data. Hyphenated techniques can provide an expanded analytical capability through the linkage of two or more spectral or separation systems that possess synergistic properties (3). In this article we discuss applications of three systems having great potential for improved environmental analysis. These are directly linked gas chromatography/Fourier transform infrared/ mass spectrometry (GC/FT-IR/MS), thermosprayhiple quadrupole mass spectrometry (TQMS), and inductively coupled plasmdmass spectrometry (ICP/MS). Some aspects of these hyphenated systems have been reviewed elsewhere (4-6). The flow scheme shown in Figure 2 outlines the sequencing of sample introduction, analyte ionization, and data collection for these three (and related) hyphenated techniques. Direcily linked FT-IRIMS systems A directly linked FT-IR/MS system has important advantages such as the following for environmental semi- or nonvolatiles analysis. FT-IR and QMS spectral data can be collected simulta-
~~~
Figure 2. Hyphenated quadrupole analyte separation, introduction, ionization, and detection scheme. ANALYTICAL CHEMISTRY, VOL. 60, NO. 7, APRIL 1. 1988
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3iio
1390
2d80
70,
250
50
Wavenumbers Figure 3. On-line compound class confirmation of Z4.5-T waste semivolatile by (a)FT-IR and (b) quadrupole detectors. (Adaoted from Gurka. 0. F.: Betowski. L. D.: Jones, T. L.: W e , S. M. J. Chmmatw. Sci. 1988, 26. In orass. by permission of Preston Pubiications. A Division of Presion Industries. Inc.)
neously, thereby providing complementary spectral data. QMS can provide molecular weights, halogen isotopic clusters, and other characteristic substructural information. FT-IR can distinguish isomers, provide group frequency data, and absorption coefficients for quantitation. In addition, the system can minimize dependence on certified standards by using FT-IR to confirm QMS identifications, using FT-IR to decrease the uncertainties associated with QMS tuning problems (QMS used alone requires standards foi user-created spectral libraries to ensure analyte and reference spectral comparability), and using FT-IR absorption coefficients to eliminate the need for quantitation standards. Ahsorption coefficients obtained from FT-IR should exhibit instrument-toinstrument reproducibility greater
nd FT-IRIMSSD selectivities
I, MSI Environmental sample
Dye waste no. 1 Dye waste no. 2 Dye waste no. 3 Herbicide
NO.Wtectea
FT-IR
MSD
The complexity of environmental samples, coupled with the inaccessibility of certified standards, ensures that compound class confirmation generally will be the best result obtainable in the environmental nontarget compound approach. Figure 3 shows a striking example of the capability of a directly linked GC/ FT-IR/MS system for assessing analyte toxicity without the determination of analyte identity. The analyte was a constituent of a 2,4,5-T manufacturing waste. The data from the quadrupole mass spectrometer indicated a 4-chlorine isotopic cluster and five sites of unsaturation. FT-IR indicated two adjacent and one isolated benzene hydrogen in an aryl ether. This indicated one aryl chlorine and three chlorines in a fused-ring cyclic ether. Thus both the alpha and beta ether positions cannot
than that obtained from grating IR instruments, but this capability has yet to he demonstrated. The commercial availability of gas chromatographic interfaces for FT-IR and QMS systems resulted in early reports of their successful linkage (7,8). These reports were soon followed by the first published environmental applications of directly linked GC/FTIR/MS systems using both a quadrupole mass spectrometer ( 9 ) and an ion trap (10). Particularly striking was the finding that 42% of the jointly detected analytes in environmental samples were confirmed by identity ur compound class (see Table I). Compound class confirmations are useful because they are not dependent on the availability of large search libraries and because class information may be sufficient to assess biological hazard (11).
Meet crlteriab
FT-IR
MSD
Compound class (tentative) FT-IR MSD
1
3
1
1
1
1
4
6
1
4
1
1
-
I
still bonom
Pesticide soil Chlorohydrocarbon soil Total
54
106
_.
source: Reference 9. a MSD = mass seiectiw detector. Meet the reporting Criteria for GCIMS and WIFT-IR structure assignments cited in Reference 9. Sample CMllained many aromatic isomers. MSD used done can only determine compound class. dUnique FT-IR information. 'Unique MSD information. Number of identificationsincreased to 18 when the probability-based matching (PBM) algofithm was used in piace of the previous system sonware
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contain inert substituents of the gemdichloro type. The unknown must then represent a powerfully electrophilic alpha or beta chloro ether that can be mutagenic via biomolecule alkylation (12).
Although directly linked GC/FT-IR/ MS systems are now commercially available, progress on the development of such systems for environmental nonvolatiles has been slow. These nonvolatiles comprise the greater portion of environmental sample extractables, and the nonvolatile fraction of water or other environmental sample types is often mutagenic to the Ames test (13).Currently, progress in achieving standalone QMS systems for multicomponent nonvolatiles analvsis is much further along than that for stand-alone FT-IR. The availabilitv of FT-IR instrumentation capable of nonvolatiles analysis is being delayed until solutions are obtained to the problems ofcontinuuus flow versus solvent elimination1 FT-IR and of high.performance liquid chromatography (HPLCJversussuper. critical fluid Chromatography 6 C F j FT-IR ( 1 4 ) . The recent disclosure of a potentially universal FT-IR chromato. graphic interface (GC, HPLC, SCF) may provide a permanent resolution to une of these difficulties (15).This universality is dependent un the need of many chromatographic interfaces for mubile-phase removal. For maximum application to environmental analysis, such an interface should be compatible with high.wacer-content, reversedphase HPLC solvents. However, confirmatory nonvolat iles analysis may still be carried out by uffline diffuse reflectance FT-IR (DRIFT) and thermospray/TQMS or fast atom bombardment IFABJ QMS. Diffuse reflectanre is a surface sampling technique that uses a film of analyre deposited on an IR-transparent solid substrate (pure solid analytes may be directly mixed with the sub-
strate). Thus HPLC fractions may be deposited directly on the substrate, the solvent removed, and the analyte-film substrate scanned by FT-IR. Although the HPLC fractions are not analyzed on line, total DRIFT sample preparation and analysis time is typically less than 5 min per component. Figure 4 shows the DRIFT and confirmatory GCIMS spectra of a 2,4,5-T waste nonvolatile, which was not amenable to conventional GC until derivatized, but was directly amenable to DRIFT as the acid salt. Thermospray/TOMS This hyphenated technique is unique in that separated ions rather than separated analytes may he presented to an analyzer quadrupole; the presence of a third quadrupole allows the generation of daughter ion profiles by collisionally activated dissociation (CAD). These profiles are used in conjunction with the pseudomolecular ions generated by the “soft” thermospray approach, in
which they are mass-separated in the first quadrupole. If an HPLC is used to provide multicomponent separation for the thermosprayITQMS, on-line environmental nonvolatiles and semivolatiles capability with a single analysis can be achieved. Table I1 lists examples of distinct types of TQMS environmental applications. First, the mild chromatographic separation conditions of thermospray are amenable to thermally labile carbamate and organophosphorus pesticides; second, the thermosprayITQMS approach can be used to characterize toxic environmental nonvolatiles; third, one of the TQMS quadrupoles can be used to minimize sample cleanup and eliminate chromatographic separation; and fuurth, the first quadrupole can be used to select parent ions that are then subjected to CAD fragmentation in quadrupole 2 (reaction monitoring). Obviously the third item could result in a significant decrease in analytical cost. Much of the early TQMS work cen-
Figure 4. identification confirmation of 2.4.5-T manufacturing waste (a) nonvolatile by DRIFT and (b) derivatized nonvolatile by OMS 458A * ANALYTICAL CHEMISTRY, VOL. 60, NO. 7, APRIL 1, 1988
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components is shown in the positive ion thermosprayD’QMS spectrum of commercial Basic Red 14 (see Figure 5). Because thermospray is a “soft” ionization technique, the peaks at m/z 174, 189, 291, and 344 were attributed to protonated molecules or molecular ions of the dye mixture (see box). Each of these ions was selected in quadrupole 1 and subjected to CAD in quadrupole 2. The CAD-induced fragmentation patterns allowed the assignment of structures 1-4 to these ions, and m/z 174,189, and 291 wereattrihuted to the protonated molecules or molecular ions of Basic Red 14 (m/z 344) dye precursors. Another quadrupole technique with great potential for environmental nonvolatiles analysis is the monodisperse aerosol generator for introduction of liquid chromatographic effluents (MAGIC). This approach converts an HPLC effluent to a physically homogeneous aerosol (21),but it has yet to be evaluated for environmental analysis.
Inductively coupled plasmalmass
tered on demonstrating that this technique could shorten analysis time by minimizing sample cleanup and chromatography (16,17)rather than on emphasizing the higher information content derived from a system possessing both CAD and analyzer quadrupoles. Although there is some empirical evidence that analysis time is shortened, TQMS real sample data collected over a long period of time are required to demonstrate that system downtime does not negate the cleanup-chromatography time savings. An approach that should not “dirty” the TQMS, and thus not lead to downtime, is the direct analysis of gaseous mixtures. A project is underway within the EPA to directly analyze gaseous mixtures in the field by employing a mobile-van-based TQMS (18). Perhaps the most exhaustive environmental study thus far that uses thermosprayDQMS has concerned the characterization of dyes. Dye wastes, degradation products, and dye intermediates form a class of highly carcinogenic compounds that currently are being discharged into the environment. These compounds present a difficult analytical problem, because they are intractable mixtures of thermally sensitive and photosensitive nonvolatile compounds. Ballard and Betowski have demonstrated the applicability of thermosprayD’QMS to the characterization of azo, methine, anthraquinone, coumarin, triarylmethane, and xanthene dyes (19,ZO). Detection limits of
2-200 ng and precision comparable to that obtained from HPLC with ultraviolet detection have been demonstrated. ThermosprayD’QMS is believed to be the current method of choice (and perhaps the only viable method) for the routine monitoring of dye-manufacture and dye-use effluents. An example of the power of CAD to identify unknown nonvolatile mixture
spectrometry Commercial instruments that use an inductively coupled plasma as an ion source for QMS became available in 1983. ICP/MS combines a sensitivity approaching that of GF-AAS with the throughput capabilities of multicomponent ICP-AES. This has prompted a number of investigations into the applicability of ICP/MS to environmental samples. McLaren determined seven elements in seawater following preconcentration by ion exchange (22). The preconcentration step was necessary because the natural levels of some
i
Figure 5. ThermospraylTQMS positive ion spectrum of the nonvolatile mixture, Basic Red 14. (Adapted horn AMI. Chem. 1984, 56.2604-07.)
ANALYTICAL CHEMISTRY, VOL. 60, NO. 7, APRIL 1. 1988
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ea 1
1
rnjure6. Frequency of detection by ICPIMS for 45 elements in lakes in the eastern United States. Analyses were osrtotrned in a rmid rnUnlelememl mode. System detecllan limits were senerally less hall 0.2 ppb.
of the metals in seawater are below the detection limits of ICP/MS. Ion exchange also allowed the separation of the trace elements from the high salt matrix, which would have caused severe suppression effects. Garbarino used isotopic dilution to determine trace metals in natural waters (23),and McLaren used the same technique for the analysis of marine sediments (24).The applicability of the isotopic dilution technique is an advantage of ICP/MS in environmental analyses because recoveries are often low. T h e method of standard additions (MSA) must be employed in most analyses by GF-AAS. Isotopic dilution is inherently more precise than MSA because the concentration is obtained in a single analysis. Isotopic dilution also requires about one-third the analysis time of MSA. The results of earlier studies of the application of ICP/MS to environmental samples encouraged EPA to incorporate the method into the Eastern Lakes Survey (ELS) of the Aquatic Effects Research Program. The intent was to demonstrate and use the capabilities of this new technology in a large-scale environmental survey with rigorous quality-assurance criteria (25). The ICP/MS analyses will provide additional insight into the effects of acidic deposition in aquatic systems by supplementing data obtained by conventional methods. A total of 267 samples from 118 lakes in the eastern United States were analyzed by ICPI MS. Calibration standards were used for 22 elements, some of which acted as models for the response of approximately 30 more analytes. ICP/MS allows the confident use of such surro-
gate elements hecause of its similar sensitivity for elements of like mass and ionization energy. Figure 6 shows the percentages of the sampled lakes that had detectable concentrations for the indicated analytes. It is obvious that lake waters, like seawater, pose a challenge to the sensitivity of even ICP/MS. The survey data currently are being evaluated to determine relationships among trace-element concentrations and between trace elements and other parameters (e.& pH, alkalinity, sulfate, watershed charaderistics, etc.). These interactions are quite complex, and multivariate statistical approaches are being applied to the data. Figure 7 illustrates some simple trends that are
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ANALYTICAL CHEMISTRY, VOL. BO.
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often observed within subsets of similar lakes. The mean concentrations of trace elements are shown for two groups of lakes from the same geographical region and general classification. All else being equal, higher concentrations of aluminum, first-row transition elements, rare earth elements, and lead are associated with lower pH values. In addition to its multielemental capability, ICP/MS can be used to determine elemental isotopic ratios. As early as 1974, Doe and Stacey of the U.S. Geological Survey had postulated that lead isotopic ratios were characteristic of specific ore deposits (26). This suggested that isotopic ratios may he used to track some environmental contaminants to their source, resulting in regulatory or remedial action. Hinners et al. have measured the m/z 208/206, 2071 206, and 204/206 isotopic ratios by ICP/MS for lead ores mined in Idaho, Missouri, and Yugoslavia, as well as for other lead standards (27). Isotopic ore ratios for these areas differed by as much as 19%.If these isotopic ratio differences are typically outside the experimental error, this approach to pollutant tracking has a bright future. Previously, Rahn and Lowenthal reported that elemental tracers can be used to pinpoint the regional sources of atmospheric aerosol pollution (28). The extra selectivity associated with elemental isotopic ratios, and the high sample throughputs required to validate such a tracer technique, may he achieved with ICP/MS.
Future Insi~~mentetlon needs Commercially available hyphenated quadrupole techniques are providing new and efficient solutions to the prohlems of complex environmental sample analysis. Nevertheless, additional sup-
: Rb
Ea'
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NdF
Flgure 7. Typical relationships observedbetween lake pH and trace elemental concentrations measured by ICPIMS. Other factors such as geqraphlc location are held constant. Each COnCentration is Wm mean 01 5 lakes. * = co"cBntratio" x Io: * = c0"Ce"Iratio" x 100 * * * = cO"cBnIra1lcf x 1000.
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ort is required from the private sector, s indicated by the needs cited in Table [I. Viable on-line multicomponent, onvolatiles capability is not available >r stand-alone FT-IR, much less for nked FT-IR/MS. Flow-cell FT-IR ystems have been available for years, ut their insensitivity, coupled with he “solvent window” problem, has reatly limited their use. Techniques to provide electron-ion!ation-type nonvolatiles fragmentaion (29),which are less expensive than ’QMS collisionally activated dissociaion, are needed to complement the Dft thermospray approach (however, ’QMS system prices have recently delined [30]).Preliminary claims indiate that the MAGIC technique may atisfy this need (21). In addition, uadrupole interfaces with multieomNonent capability, which are also ametable to low-proton-affinity uonvolailes, are required to support thermopray/TQMS. Wider mass range qnadupole mass spectrometers are needed o meet the demands of high-molecux-weight, nonvolatile environmental ontaminants. In the area of inorganic analysis, here is increasing awareness that race-metal speciation information is sften more environmentally significant han total metal concentration. Thus nterfacing ICP/MS with HPLC and >n chromatographs will be necessary n the future. Flow-injection sampling ystems or robotics would make the iotopic dilution technique more viable or routine analysis. “Intelligent” data
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acquisition and analysis software, comhined with automated sampling and instrument control systems, could greatly increase ICP/MS throughput by automatically ordering sample dilutions, plasma parameter changes, or other manipulations, depending on the results obtained in an initial scan. This would not only increase dynamic range, but it would also help to ameliorate the matrix effects often encountered in complex hazardous waste samples. Although the foregoing needs involve improvements to existing instrumentation, no progress in providing chromatographic interfaces for NMR systems has been forthcoming from the private sector, despite demonstrations of feasibility by the researchcommunity (3233). The high molecular selectivity of NMR, the availability of large collections of NMR reference spectra, and the nondestructive nature of the technique make it a logical choice for quadrupole linkage. When a more complete evaluation of the strengths and weaknesses of linked FT-IR/MS becomes available, the need for multicomponent NMR capability will he clearly defined and a potential instrumentation market should he revealed. A discussion of the instrumental needs of hyphenated quadrupoles should not omit the requirement for structural interpretation software. This need is particularly acute for quadrupoles linked to spectral detectors. Some progress along these lines is already evident from the research community (34).
Future directions In a world in which the number of new chemicals reported yearly is estimated at 4 X lo5 ( I I ) , unique approaches will be required to delineate the environmental risks posed to man. To be successful, these approaches must be economical and must rely heavily on automation. It is anticipated, that complete characterization of environmental samples will be impractical and uneconomical. What is needed is the ability to characterize the most abundant toxic constituents, regardless of their volatility or of the availability of authentic standards of these constituents. A proposed and integrated approach to this goal includes the following steps. Automated sample cleanup by robotics or other suitable methods. Inexpensive in vitro biological screening. Screening organisms should be chosen such that results can be extrapolated to humans. Hyphenated QMS chemical analysis of samples producing biological screen positives. Computer-established molecular structure assignment from hyphenated QMS data. Integration of final data into computerized risk and hazard assessment schemes (41). Each of these scheme components is the subject of ongoing research. Thus it may be time to consider what is necessary to implement such an approach, or other suitable approaches, that can meet the challenge of potentially rapid increases in the complexity of environmental contamination. Although the research described in this article has been supported by the Environmental Protection Agency, it has not been subjected to Agency review and therefore does not necessarily reflect the views of the Agency. No official endorsement should be inferred.
Ref(1) Dawson, P. H. Mass Spectrom. Rev. 1986,5,1-37. (2) Fed. Regist. 1979,44 (223), 69464-75. (3) Hirschfeld,T. Anal. Chem. 1980,52, 297 A-312 A. (4) Vestal, M. L. Mass Spectrom. Rev. 1983,2,441-80. (5) Houk, R. S. Anal. Chem. 1986,58,97 A105 A. (6) Wilkins, C. L. Anal. Chem. 1987,59, 571 A-581 A. (7) Wilkins, C. L.; Giss,G. N.; White, R. L.;
Brissey, G. M.; Onyiriuka, E. C. Anal. Chem. 1982,54,2260-64. (8) Crawford, R. W.; Hirschfeld, T.; Sanborn, R. H.; Wang, C. M. Anal. Chem.
1982,54,817-20. (9) Gurka, D.F.;Titus, R. Anal. Chem. 1986,58,2189-95. (10) Olson, E. S.; Diehl, J. W. Anal. Chem. 1987,59,443-48. (11) Arcos, J. C. Enuiron. Sci. Technol. 1987.21.743-45. (12) Fhd’hrg, E.C. D N A Repair; W.H. Freeman: New York, 1985; 542. (13) Tabor, M. W;;Loper,J. Miles, S. K.
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Impact and Health Effects;Jolley. R. L.; Brungs. W. A,; Cumming, R. B.; Jacobs,
V. A,, Eds.; Ann Arbor Science: Ann Arbor, Mich.. 1980; Vol. 4,pp. 1199-1210. (14)Griffiths. P. R.;Pentoney. S. L., Jr.; Giorgetti, A,; Shafer. K. H. Anal. Chem.
1986.58.1349 A-1364 A. (15) Pentoney, S. L., Jr.; Giorgetti. A,; Griffiths. P. R. J. Chromatogr. Sei. 1987.25. 02-47 ""
(16) Yost, R. A,; Fetterolf, D. D.; Ham, J. R.;Harvan, D. J.; Weston, A. F.; Skotnicki. P. A.; Simon, N. M. Anal. Chem. 1984,56,2223-28. (17) Hunt, D.F.; Shabanowitz. J.; Harvey, M.; Coates, M. Anal. Chem. 1985,57,525-
1987; Abstract 75,184.
, B. R.; Stacy. J.S. Econ. Ceol.
I
-
1
mar, E. M.; J . M . Anal.
,A,; Lowenthal. D. H. Sci'23,132-38. (29) Barman. S. Anal. Chem. 1987. 59, A .. . . ....
7fiQ A-774
(30) Borman. S. Anal. Chem. 1986. 58. 406 A 4 1 2 A. (31) Buddrus. J.; Herzog, H. Org. Magn. Reson. 1481, 15, 211-13. (32) Darn, H.C. Anal. Chem. 1984. 56, 747 A-758 A. 17 "I. (33) Laude, D. A., Jr.; Wilkins, C. L. Anal. (18) Billets,S.;Engels,J.L.;Kerfoot,H.B.; Chem. 1987.59,54651. Amold, D. F. "Survey of Mobile Labora(34) Hippe. 2: In Computer Sup orted tory Capabilities and Configurations," Spectroscopic Databases; Zupan, Ed.; EPA 600iX84-170; E P A Washington, John Wiley and Sons: New York. 1986; D.C., 1984: pp. 23-25. Chapter 8. pp. 155-60. (19) Ballard. J. M.; Betowski, L. D. Org. (35) Voyksner, R. D.;Bursey, J. T.; PellizMass. Spectrom. 1986.21.575-88, zari. E. D. AnaLChem. 1984.56.1507-14. (20) Betowski. L. D.; Pyle, S. M.; Ballard. (36) Hummel, S.V.; Yost, R. A. Org. Mass J. M.; Shaul, G. M. Riomed. Mass SpecSpectrom. 1986,21,785-91. trom. 1987.14,343-54. (37) Wong. C. M.; Crawford, R. W.; Yost, (21) Willoughby, R. C.; Browner, R. F. R. A. In Mass Spectrometric ChamcterAnal. Chem. 1984.56,262631. ization of Shale Oils; ASTM Standard (22) McLaren, J. W.; Mykytiuk. S. N.; WilTesting Procedure 902, Anel, T.. Ed: lie, S. N.; Berman, S.S. A n d . Chem. A S T M Philadelphia, 1986, pp. 1W-20. l985,57.2907-11. (38) Thompson. J. J.; Houk, R.S. Anal. (23) Garbarino, J. R.;Taylor. H. E. Anal. Chem. 1986,58.2541-48. Chem. 1987,59.1568-75. (391 Koroochak. J.A.: Winn. D. H. Anal, (24) McLaren, J. W.; Beauchemin, D.; Berman. S. S. Anal. Chem. 1987,59.610-13. (25) Henshsw. J. M.;Heithmar, E. M.; Hinners, T. A. Presented at the 29th Rocky Mountain Conference, Denver, Colo.,
f,
Donald F. Curka ( l e f t )receiued his R.S. degree from Columbia Uniuersity and his Ph.D. degree i n physical chemistry from the Uniuersity of Washington. He is currently employed at EPA, where his research interests include the deuelopment of enuironmental assays, hyphenated techniques, FT-IR spectrometry, and linear free-energy relationships. John M. Henshaw (second from left) receiued his B.S. degree from Western Washington State College. Currently he is a chemist with Lockheed-EMSCO. His research interests include trace elemental analysis. L. Donnelly Betowski (third from left) receiued his B.S. degree from Georgetown Uniuersity and his Ph.D. in physical chemistry from Cornell Uniuersity. His interests as a research chemist at E P A include environmental applications of LCI MSIMS, LCIMS, and GCIMS. Edward M. Heithmar (fourthfrom l e f t ) receiued his B.A. degree from Biscayne College (Miami) and his Ph.D. i n analytical chemistry from the University of Pittsburgh. He is a research chemist at EPA, where his research interests include the deuelopment o f trace elemental techniques using atomic absorption and plasmalmass spectrometry. Richard Titus ( f i f t h from left) is professor of chemistry at the Uniuersity of Neuada at Las Vegas. His research interests include hyphenated techniques, NMR, and organosulfur chemistry. Thomas A. Hinners did his undergraduate andgraduate work at George Washington University and studied the work of Wolfgang Weber and Gerd Muller (DFB) in Germany. Since 1970 he has been inuolued i n trace element studies o f biological and enuironmental media.
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