432 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Anal. Chem. 1083, 55, zyxwvu 432-435 Flgure 10. zyxwvutsrqponm Elution profiles flowmeter-derived profiles. an SEC experiment. We have carried out many variations of flow perturbations during typical analyses and have yet to find conditions that the flowmeter cannot accommodate. zyxwvutsrqpo LITERATURE CITED zyxwvutsrqponmlkjihgfedcb Bly, D. D.; Stoklosa, H. J.; Kirkland, J. J.; Yau, W. W. Anal. Chem. 1975, 47, 1810-1813. "Flow Precislon in a New HPLC Pumping System"; Du Pont Liquid Chromatograph Technical Report; Analytical Instrument Division, Con- cord Plaza, McKean Bldg.: Wllmlngton, DE. Schuiz, W. W. zyxwvut J. Li9. Chromatogr. 1980, 3, 941-952. Letot, L.; Lesec, J.; Qulvoron, C. J. Ll9. Chromatogr. 1980, 1637-1655 Baker, D.-R.; George, S. A. Am. Lab. (Falrfield, Conn.) 1980, 42-46. Mori, S.; Suzukl, T. J. Li9. Chromatogr. 1980, 3, 343-351. ~ , Miller, T. E., Jr.; Small, H. Anal. Chem. 1982, 54, 907-910. (8) Yau, W. W.; Kirkland, J. J.; Bly, D. D. "Modern Size-Exclusion Liquid Chromatography"; Wiley: New York, 1979; p 294. (9) "Scientific Subroutines Proarammer's Reference Manual". AA-1101D. for dramatically changing flow rates, the are shown in Figures 8-10, The use of the flowmeter for elution volume measurement comdetelv accommodates the Digital Equipment Corp., h h n l c a i Documentation Center, Cotton Road, Nashua, NH 03060, revised, June (1980). dramatic flow changes occurring d&ng these experiments and also quite adequately accounts for any concievable (and even some inconcievable) variations in flow rate occurring during RECEIVED for review October 15, 1982. Accepted December 3, 1982. Peroxyoxalate Chemiluminescence Detection of Polycyclic Aromatic Hydrocarbons in Liquid Chromatography Kenneth W. Slgvardson and John W. Birks" Department of Chemistry and Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado, Boulder, Colorado 80309 Peroxyoxalate chemlluminescence is applied to the hlgh- performance llquld chromatographlc detectlon of polycyclic aromatlc hydrocarbons (PAH). PAH are excited by energy transfer from the decomposition products of the reactlon be- tween hydrogen peroxide and bls(2,4,6-trichlorophenyl) oxa- late. These reagents are Introduced by postcolumn mlxlng, and the emission Is observed by uslng a conventlonal fluorescence detector wlth Its source turned off. The method yields llnear reponses to PAH over 3 orders of magnltude, and In some cases detectlon llmlts are better than those deter- mlned by fluorescence uslng the same fluorometer. Cheml- lurnlnescence detectlon Is compared to ultravlolet absorbance and fluorescence detectlon of PAH In terms of sensltlvlty and selectlvlty . Polycyclic aromatic hydrocarbons (PAH) represent the largest class of chemical carcinogens occurring in the envi- ronment. The sources of environmental PAH are due to a variety of processes-both natural and anthropogenic. High-temperature combustion processes have become the major contributors in most urban areas (1). Due to the large number of chemical events which can take place in a com- bustion process, the mixtures of PAH produced are extremely complex. Currently, there is no single analytical method capable of providing the complete analysis of complex PAH mixtures. High-resolution gas chromatography and high- performance liquid chromatography (HPLC) are the two most commonly used methods of separating PAH mixtures. High-resolution gas chromatography provides the highest separation efficiencies and is necessary in the separation of the most complex PAH mixtures. HPLC detection of PAH, on the other hand, is aided by the selectivity of ultraviolet absorbance and/or fluorescence detectors. In this paper the application of a new chemiluminescence method to HPLC analysis of PAH is described and evaluated. Peroxyoxalate chemiluminescence is the most efficient non- enzymatic chemiluminescent reaction known, having quantum yields as high as 25% (2). The chemiluminescent reaction is illustrated by the reaction of an oxalic ester, such as bis- (2,4,6-trichlorophenyl) oxalate (TCPO), with hydrogen per- oxide and a fluorescent compound: FLUOROPHOR*+ FLUOROPHOR ' r hu Hydrogen peroxide and the oxalic ester react, forming in- termediates capable of transferring as much as 106 kcal/mol of energy to the fluorescent acceptor (3). The postulated key intermediate is 1,Z-dioxetanedione (4). Once excited, the fluorescer emits its characteristic light, as it does in fluores- cence detection. The first analytical application of peroxyoxalate chemilu- minescence was reported in 1976 by Seitz and co-workers (5). Hydrogen peroxide was measured in a flow injection system and was found to have a linear working range of more than 4 orders of magnitude. This system has since been improved 0003-2700/83/0355-0432$01.50/0 C 1983 American Chemlcal Society