&EPA United States Environmental Protection Agency Environmental Monitoring Systems Laboratory P.O. Box 93478 Las Vegas NV 89193-3478 June 1993 OFFICE OF RESEARCH AND DEVELOPMENT TECHNOLOGY SUPPORT PROJECT Field-Portable Scanning Spectrofluorometer AnEMSL-LV Innovative Technology The Need: Field-portable instru- ments are available for the qualitative and quantitative evaluation of volatile organic compounds and non- volatile inorganic elements. Compounds that fall between these volatility extremes have received less attention in recent years. And yet these compounds comprise a surprising number of important contamination catego- ries at Superfund and RCRA sites. Polyaromatic hydrocar- bons (PAHs) in com- plex mixtures such as oils, creosotes, and tars are found on numerous hazardous waste sites and, because of their high molecular weight, present special chal- lenges to analytical chemists and instru- ment developers. These compounds have relatively high lumines- cence yields and, therefore, can be readily measured by spectroflu- orometry. A recent technology that is in the production prototype stage is the Field-Portable Scanning Spectrofluorometer (FPSS). It is a light- weight battery-operated instrument that has shown early promise as a screening device for petroleum oils, PAHs and, especially, creo- sotes. Creosote (wood preser- vation) and coal gasifi- cation sites are wide- spread, especially in the southeastern United States. These are complex sites that usually have various PAHs in addition to the creosotes. These compounds are cur- rently quantified by gas chromatography but their tarlike composition makes them difficult to detect and destructive to columns and detec- tors. The development of a field-portable instrument to rapidly identify and quantify PAH mixtures, such as creosotes, oils, as- phalts, or coal tars is an important step in filling a field analytical niche. The FPSS prototype is ready for field demon- stration and compara- tive studies. It is anticipated that the FPSS will provide a more rugged and less expensive alternative to traditional methods for screening PAHs. 2016EX93ODC ------- The Use: Scientists working at the Environmental Monitoring Systems Laboratory-Las Vegas have performed labora- tory evaluations of the battery-operated FPSS developed by T. Vo- Dinh and his co-work- ers at Oak Ridge National Laboratory.1'23 Table 1 shows the physical characteristics of the instrument. The FPSS can perform emission and synchro- nous wavelength scans. In the emission mode, relatively low detection limits are achieved (Table 2). The emission mode is useful for the determi- nation of total PAHs or in identifying and classi- fying oils. In the syn- chronous mode both the excitation and emission monochroma- tors are scanned simul- taneously with a con- stant wavelength offset. The advantage to syn- chronous mode is that it separates spectra of compounds with a different number of fused rings, sharpens spectra, and allows the relative amount of various PAH classes to be quantified. The FPSS consists of three parts: a small Table 1. Physical Characteristics of the Field- Portable Scanning Spectroltuorometer SIZE WEIGHT Instrument Battery Pack 48x40x21 cm (18.5 x 11.5x8") 31 K18 x 15 cm (12x7x6") 11.5 kg 11.0 kg suitcase-sired instru- ment that houses the optics and electronics, a battery pack, and a lap top computer used for instrument control, data storage and analysis. The spectra! coverage of the instru- ment is 210-650 nm. The instrument param- eters are chosen by the operator who uses the computer to control the instrument. The FPSS can be oper- ated two ways: using a standard fluorescence cuvette cell or a bifur- cated optical fiber. The optical fiber attachment is 2-meter long and allows direct screening of water samples. The cuvette can be used with liquid samples or extracts of soils. When the optical fiber attach- ment is used, care must be taken to avoid inter- ference from light. This can be done by cover- ing the sampling area with a black cloth. Table 2. Limit of Detection (S/N = 3) SYNCHRONOUS EMISSION SYNCHRONOUS (cuvette) tcjv&tte) ,'ftai; Petkin Elmer LS50 0.17* 0.02 24 (laboratory instrument) FPSS prototype 3.5 0.55 1 ' All concentrations ng/mL of anthracene The Limits: Some areas of concern exist relative to the successful operation of the FPSS in a field situation. The rugged- ness of the optical components is crucial to the in situ applicabil- ity of the system. The unit was shipped from Oak Ridge National Laboratory to the EMSL-LV without affecting the optical alignment or electron- ics. The instrument has been demonstrated to withstand norma! handling in the labora- tory. The instrument is (continued on next page) ------- The Limits: (continued) The Status: ready to be demon- strated at a hazardous waste site. The FPSS is particu- larly suited to the classification or identifi- cation of oils or PAH compounds. It can also be used with site- specific standards to quantify total oils or PAHs. It can be used to determine relative amounts of the PAH classes present. In rare instances, like spills of solvents or PAHs with very high fluorescent yields and sharp structures such as benzo-(a)pyrene, it can be used to detect and quantify identified PAHs. There is greater spectral separation capability when the instrument is operated in synchronous mode but lower detection limits can be achieved using the emission mode. Laboratory evaluations and research efforts have resulted in a draft fluorescence method for the analysis of PAHs which is in the final stages of accep- tance by the American Society for Testing and Materials. A compari- son of the optical fiber mode and the standard cuvette mode was per- formed on samples of anthracene in metha- nol. This study showed the cuvette mode to be 2-3 times more sensi- tive than the optical fiber mode. Synchronous lumines- cence has been dem- onstrated to be useful in characterizing crude and fuel oils.4 The technique can be used to produce spectral fingerprints for the identification of oil contamination types and sources. The FPSS proved its ability in a study comparing samples from an oil spill with samples of the source oil which were provided by the U.S. Coast Guard. The FPSS has shown considerable promise for the classification and quantitation of PAH compounds and oily mixtures. The next step is to take the portable instrument to a hazardous waste site where it can be evalu- ated against standard methods in a well- planned experimental design. The develop- ment of the FPSS was sponsored by the EMSL-LV and commer- cialization is being planned. References: 1 T.Vo-Dinh, "Synchronous Excitation Spectroscopy" in Modern Fluores- cence Spectroscopy, Vol. 4, Edited E.L. Wehry, Plenum Press, New York, 1981, pp. 167-192. 2 T. Vo-Dinh, "Synchronous Luminescence Spectroscopy: Methodology and Applicability", Applied Spectroscopy, Vol. 36, 576,1982. 3 J.P. Alarie, Vo-Dinh, T., Miller, G., M.N. Ericson, S.R. Maddox, W. Watts, D. Eastwood, R.L. Lidberg, and M. Dominguez, "Development of a Battery- Operated Portable Synchronous Luminescence Spectrofluorometer", in press, (Review of Scientific Instruments). 4 K.J. Siddiqui, Lidberg, R.L., Eastwood, D., and Gibson, G., "Expert Sys- tems for Classification and Identification of Waterborne Petroleum Oils", Monitoring Water in the 1990s, Meeting New Challenges, ASTM STP 1102, J.R. Hall and G.D. Glysson, Editors, American Society for Testing and Materials, Philadelphia, 1991. ------- The Contacts For further information about synchronous luminescence spectroscopy, contact: Mr. William H. Engelmann, Manager Advanced in Situ Monitoring Program U.S. Environmental Protection Agency Environmental Monitoring Systems Laboratory P.O. Box 93478 Las Vegas, NV 89193-3478 (702) 798-2664 For information about evaluating the FPSS at a hazardous waste site (Superfund or RCRA), contact: Mr. Ken Brown, Manager Technology Support Center U.S. Environmental Protection Agency Environmental Monitoring Systems Laboratory P.O. Box 93478 Las Vegas, NV 89193-3478 (702) 798-2270 The Technology Support Center fact sheet series is developed by Clare L. Gerlach, Lockheed Environmental Systems & Technologies Company, Las Vegas ^TI0A% ^ -T- \ ^ I echnology "Z- ° O . Z O ^uPPOrt O reject M.OGY ------- |