intensities) and isotope data (names, half lives, experimentally determined $-values) is permanently present in the memory (5). An extensive description of the identification process can be found in Reference 3. ACCURACY OBTAINED IN THE ROUTINE ANALYSES
Both the accuracy and the precision of the data obtained in the standard analysis procedure were tested by analyzing Perlman’s standard pottery powder (6). Five samples of about 100 mg each were irradiated for 2 hours at a flux of 4.1012 njcmZ sec. Two measurements of 30 minutes were carried out, respectively, 5 and 30 days after irradiation. The results of the analyses, together with the recommended values for the various element concentrations, are shown in Table I. APPLICATIONS OF THE SYSTEM
At our institute, this method of nondestructive neutron activation analysis is currently applied to various research projects in which large series of samples are involved. (5) IM. de Bruin, P. J. M. Korthoven, and N. v.d. Drift-Holtslag, “Gamma rays from isotopes produced by (n.7)-reactions,” IRI
Report 133-71-06(k971). (6) I. Perlman and S. Asaro, Archaeometry, 11, 21 (1969).
River Sediments, Soils, and Their Vegetation. Routine analysis provides information about the degree of contamination by heavy metals. Also the distribution and behavior of these and natural elemental constituents of sediments and soils in contact with fresh and salt water and during cultivation are being studied. Moreover, silt transport in estuaries (7) and efficiencies of tilling techniques are being studied using activable tracers. Prehistorical Flints. Recently a method was developed for the identification of the origin of flint artifacts (8). In this method, a pattern recognition analysis is applied to flint samples using 15 trace element contents as determined by the previously described activation analysis system. When testing this method on 60 flints, only one of them was erroneously identified. This combination of trace element analysis and pattern recognition will also be applied to sediment transport studies and to stratigraphic studies in geology.
RECEIVED for review March 21, 1972. Accepted August 7, 1972. (7) A, J. de Groot, E. Allersma, M. de Bruin, and J. P. W. Houtman, Proc. IAEA Symp. “Isotope Hydrology,” Vienna, 885
(1970); IRI Report 133-70-06. (8) M. de Bruin, P. J. M. Korthoven, C. C . Bakels, and F. C. A. Groen, Arclimometry, 14, 55 (1972).
Multicomponent Pattern Recognition and Different iation Method Analysis for Oil in Natural Waters Ihor Lysyj and Peter R . Newton Rocketdyne-A
Dicision of North American Rockwell, Canoga Park, Calif. 91304
THEE N \ IRONMENTAL AND ECOLOGICAL degradation of natural waters resulting from oil spills and leaks is a well-recognized fact of life today. The petroleum oils are released into aquatic environment continuously by shipping and off-shore drilling operations. Such releases are due partly to normal operating procedures and partly to catastrophic events. While the immediate visual effects of catastrophic oil spills are controllable by surface removal of oil, the long term, residual effects and the fate of oil dispersed in natural waters are largely unknown. Lack of knowledge in this case is largely due to the absence of suitable analytical techniques for the analysis of traces of oil in a water matrix. The petroleum oils are complex mixtures of hydrocarbons; and when dispersed in natural waters, they are mixed intimately with organic matter derived from biomass activity, i.e., carbohydrates, proteins, lipids, and their degradation products. Selective analytical techniques for the molecular definition of such a complex cornposition are of limited value due to the multitude of chemical species present. Nonselective methods, such as the determination of total organic carbon, arc also of little value, since they do not differentiate bctween biomass related organic conpounds and petroleum related materials.
The method of analysis described here is based on the theory of multicomponent pattern recognition and differentiation. It is postulated that the matter of discrete composition can be characterized qualitatively and defined quantitatively by considering the overall pattern formed by the individual components of such composition. For example, in natural water polluted by a petroleum oil, we can expect to find a number of organic compounds contributed by a petroleum oil and a number of organic compounds derived from biomass activity. The overall patterns formed by two such different compositions of matter would be different, and when developed by physical means, should be differentiable by the application of suitable mathematic techniques. The physical and mathematical methodology for such differentiations was described in 1970 by Lysyj, Nelson, and Webb (I). The method is based on thermal fragmentation of organic molecules, followed by gas chromatographic separation and detection of resulting fragments. When such molecular fragmentation is carried out in the presence of a large excess of water, processes were found to be linear with concentration ~~
(I) I. Lysyj, K. H. Nelson, and S. R. Webb, Water Res., 4, 157-63 ( 1970).
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Table I. Numerical Patterns for Algal and Oil Suspension
Peak No.
Average retention time, minutes
1 2 3 4 5 6 7 8 9 10 11 12
0.6 0.8 1.4 3.2 4.5 7.4 13.5 15.3 20.7 24.6 26.5 28.7
Response WV-seconds per 1 ppm concentration in water Algae Oil 4399
...
4898 4273 5466 3442 2716
7027 14155 39608 27868
...
...
26 108 31820 2044
6641 207 306 1135
3886 5229
... ...
Table 11. Analysis of Mixed Oil-Algae Suspensions PPM OF EACH COMPONENT OIL RUN# ALGAE 1 2 3 4
22.1 21.9 21.4 24
AVERAGE FOUND 22.35 ACTUAL PRESENT 25 PPM OF EACH COMPONENT RUN# ALGAE 1 2 3 4 5 6 7
AVERAGE FOUND ACTUAL PRESENT
27.9 25.7 34.5 32 36 40.7 20.7 31.07 37
12.5 13.1 10.7 8.2 11.12 12
OIL 8.2 8.7 7 2.9 5.7 6.4 5.9 6.4 6
and independent for each organic compound in a mixture. The pyrographic pattern produced by a mixture of organic compouiids is a simple arithmetic summation of contributing patterns of each compound present. A recorded pattern of pyrolytically produced fragments for a given water sample reflects the total nature of its organic composition, and can be interpreted and differentiated in a number of ways. Using a priori established calibration patterns for individual components to be founci in a mixture, the pattern produced by a mixture can be analyzed mathematically. The system can be calibrated and then differentially analyzed in terms of neat organic compounds, classes of organic materials, or in terms of any other arbitrarily defined organic compositions, such as are found in petroleum oil, or in a biomass produced organic matter. Normally it is possible t o set a linear equation for each peak of a composite program, and then solve a series of simultaneous equations for unknown concentrations of organic materials represented by the pyrogram. A maximum number of components, into which data can be solved, equals the number of peaks observed on a pyrogram. In previous work ( I , 2), mixtures of discrete organic com-
pounds in aqueous solutions were qualitatively and quantitatively analyzed using this method. An attempt was made in this study t o characterize pyrographically complex organic compositions, such as found in a petroleum product and algae as separate identifiable entities, and then t o determine the quantity of each in a mixed solution. Such a procedure for gross characterization and quantitative determination of multicomponent organic compositions has a potentially wide application in environmental studies. Extreme complexity of environmental systems makes examination of a phenomenon or a process in molecular terms quite often not practical. Analytical hardware and computer procedures used in this experiment were described previously (2, 3). The instrument was operated under the following conditions: temperature of pyrolysis, 650 "C; gas chromatographic column, 10 ft long, 3/16-in. diameter, packed with Porapak Q; column temperature, 110 O C ; sample size, 150 pl; and detection, hydrogen flame ionization. Dried algae and outboard motor oil were used as test materials. A specific pattern, or numerical fiingerprint, was obtained for each pyrographically, and they are compared in Table I . A total of twelve peaks was recorded for two substances. The algal pattern consisted of three specific and seven common (with oil pattern) peaks. Oil pattern consisted of two specific and seven common (with algal pattern) peaks. Numerical values for each peak of each substance were different and formed a specific identifiable pattern or fingerprint. Mixtures of oil and algal suspensions in water were prepared in various proportions and analyzed pyrographically. The composite pyrograms were then analyzed mathematically. This was accomplished by setting and solving simultaneous equations (using the intensities of six major peaks for each substance as coefficients) in least squares mode. The computation was performed by a computer, and the results are shown in Table 11. The results of the completed experiments indicate that complex organic compositions can be defined in terms of pyrographic patterns, as separate entities with identities of their own, i.e., algae, motor oil. When a number of such complex organic compositions are present in a n admixture, they can be differentiated qualitatively and quantitatively by solving a number of simultaneous equations in least squares mode. The differentiating capability of this technique is a function of a pyrogram complexity. The complexity of a pyrogram is in turn influenced by operating conditions, such as the temperature of pyrolysis and the effectiveness of GC separation. More complex pyrograms provide greater number of bits of information and permit a greater degree of differentiation in a mixture of organic materials. Relatively simple pyrograins of 6 t o 12 peaks produce, generally, fairly similar patterns for the members of a given group or a class of organic materials, but significant differences are observed between patterns of materials of different classes. Consequently, while the differences in patterns for various hydrocarbons might not be sufficiently pronounced to permit differentiation within a group, using only 6 peaks as calibration constants, the differences between the patterns of hydrocarbons and biomass composition are sufficient for differentiation and quantitative determination of each multicomponent composition. This technique also has a potential for identifying sources of oil spills in aquatic environment. Such a task, however, is considerably more difficult. To achieve ditTerentiation be.-
(2) I. Lysyj, P. R . Newton, and W. J. Taylor, ANAL.CHEM.,43, 1277--81(1971).
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(3) I. Lysyj, A ~ I GLab., T . No. 7, 23-5,(1971).
ANALYTICAL CHEMISTRY, VOL. 44, NO. 14, DECEMBER 1972
tween various sources of crude oils, far more complex pyrograms must be developed. This can be accomplished by performing pyrolysis at lower temperatures and increasing GC separation of produced derivative composition. The practical use of this method for oil spill surveillance and source identification is further compounded by the fact that the composition of spilled oil is unstable in aquatic environment. This instability is characterized by the loss of volatile and water soluble fractions, leading to eventual formation of so-called “tar balls.” The residual, environmentally stable compositions of oil spills such as found in “tar balls,” could provide a key
for oil source identification. If a sample and a standard are pretreated to remove volatile and water soluble fractions, the comparison between the patterns produced by the residual matter in a sample and a standard should be possible.
RECEIVED for review May 30, 1972. Accepted July 27, 1972. The research upon which this paper is based was performed pursuant to Contract No. 14-12-802 with the Environmental Protection Agency, Water Quality Office. H. P. Nicholson served as Project Officer.
Influence of Solvent upon the Phosphorescence Characteristics of Several Sulfonamides at 77 O K D. R. Venning,’ J. J. Mousa, R. J. Lukasiewicz,2 and J. D. Winefordner3 Unicersitp of Florida, Department of’Chemistry, Gainesville, Fla. 32601
PHOSPHORIMETRY has been shown to be an extremely sensitive analytical method of considerable use for the trace analysis of molecules, especially when coupled with separation methods. However, until the recent work of Lukasiewicz, Rozynes, Sanders, and Winefordner ( I ) and of Lukasiewicz, Mousa, and Winefordner (2, 3) phosphorimetry was limited to nonaqueous solvents and solvent mixtures which would form clear, rigid glasses a t liquid nitrogen temperature, 77°K. However, the latter group of authors (2, 3) introduced the quartz capillary cell for low temperature studies; the quartz capillary cell allowed measurement of phosphorescence of molecules in aqueous or predominantly aqueous solvents with no danger of cracking the cell. In addition, capillary cells are much simpler to clean, and so contamination is not anywhere near the problem as with previous commercial closed cells. Furthermore, the cell is much simpler to fill and empty, and so the time of analysis is considerably reduced. Because phosphorimetry has been limited to the measurement of sample solutions in rather small diameter ( ~ mm 5 i d . ) , long ( ~ 2 0cm) quartz cells, considerable positioning errors result with standard commercial holders. However, Hollifield and Winefordner (4, Zweidinger and Winefordner (5) and later Lukasiewicz, Mousa, and Winefordner (3) have developed a means of reducing random positioning errors and of allowing tneasurement of snowed and highly cracked sample matrices, as well as clear, rigid glasses by simply rotating the sample cell. The precision of measurement with the rotating phosphorimetric cell is of the same order as in fluorimetry of samples a t room temperature. Present address, 1101 Coral Way, Coral Gables, Fla. 33134. Present address, P.O. BOY76. Brea, Calif. 92621. Author to whom all correspondence should be sent. (1) R. J. Lukasiewicz, P. Rozynes. L. B. Sanders, and J. D. Winefordner, ANAL.CHEW.. 44,237 (1972). ( 2 ) R. J. Lukasiewicz, J. J. Mousa, and J. D. Winefordner, ibid.. p 1339. ( 3 ) Ibid., p 963. (4) H. C . Hollifield and J. D. Winefordner, ibid., 40, 1759 (1968). ( 5 ) R. A. Zweidinger and J . D. Winefordner, ihid., 42, 639 (1970).
Because of the recent work by Lukasiewicz, Mousa, and ‘Winefordner ( 2 ) o n the influence of mixed solvents (alcoholwater and alkali halide-water) on the phosphorescence signals of several organic molecules, the present authors decided to investigate the phosphorescence characteristics (phosphorescence excitation and emission spectra, phosphorescence lifetimes, phosphorescence analytical curves, and phosphoIescence limits of detection) of sulfanilamide, sulfathiazole, sulfamethazine, sulfadiazine, sulfaguanidine, and sulfacetamide in four different solvents: 10% sodium iodide in water; 10% sodium chloride in water; 10% methanol-water; and 10% methanol with 1 % sodium iodide in water. Previous work had shown that these solvents should result in maximal phosphorescence signals--i.e., plateau of plots of phosphorescence signal cs. solvent composition. The sodium iodide was of particular interest because of the combined matrix and heavy atom effects (3). The results of this study are compared with the results obtained by Hollifield and Winefordner (6) using a clear, rigid solvent of 100 % ethanol. Sulfonamides were chosen for this study because they have been used as chemotherapeutic agents and are still being used as bacteriostatic agents. EXPERIMENTAL
Apparatus. All phosphorimetric measurements were made with an Aminco-Bowman spectrophotofluorometer a i t h a n Aminco-Keirs phosphoroscope attachment, a 150-W xenon arc lamp, a potted RCA IP28 photomultiplier tube, and a n X-Y recorder (American Instrument Company, Silver Spring, Md.). The basic instrument was arranged as previously described (2, 6 ) with the following exceptions. A Keithley Model 244 high voltage supply (Keithley Instruments, Cleveland, Ohio) was used to provide power to the photomultiplier tube. A rotating sample cell apparatus ( 4 ) consisting of a Varian A60-A High Resolution Nuclear Magnetic Resonance Spectrometer Spinner Assembly (Varian Associates, Palo Alto, Calif.) was modified for use with a (6) H. C. Hollifield and J. D. Winefordner, A i d . Cl7im. Actn, 36,
352 (1966).
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