Anal. Chem. zyxwvuts 1904, zyxwvut 56, 2223-2228 2223 ~~ Table 11 phosphate concn M FIA analysis spectrophotometric sample (Xa) analysis (Xb) Xa - Xb 1 0.002 56 0.001 98 +O.OOO 58 2 0.005 47 0.005 37 +o.ooo 10 3 0.007 37 0.008 26 -0.00 89 4 0.002 80 0.002 71 +O.OOO 08 5 0.002 377 0.002 371 +O.OOO 006 6 0.00301 0.00334 -0.000 33 7 0.000 99 0.001 12 -0.000 14 8 0.01062 0.011 06 -0.000 44 9 0.012 03 0.011 42 +O.OOO 61 10 0.002 53 0.002 82 -0.000 29 X = 0.000071 Confidence limits = 0.000071 f 0.00033 at 95% confidence level ~~ was assessed. This assessment indicates that systems of this sort have potential for analysis in a large number of sample types at cost equal to or lower than the FIA system employing spectrophotometric detection. The added perquisites of low detection limits, simplicity, and fast sampling times increase this competitiveness. The negative aspects of this method center around the problem of iron(II1) and silicate interferences since both of these ions are found in a large number of natural and biological substances which are routinely analyzed for orthophosphate. The problem of iron removal can probably be solved by pretreating samples either in the flow system or before in- jection by passing them through an ion exchange column or a column filled with a chelating resin. This may be accom- plished simply and should serve to remove other possibly interfering cations from the sample. Interference from silicate ion is a more difficult problem which can be partially solved by increasing the nitric acid concentration in the sample and mobile phase. This could not be done in our system however without greatly decreasing base line stability and noise characteristics. It is planned to continue work on this problem in our laboratory in order to make this method more competitive with present spectro- photometric techniques. Registry No. Orthophosphate, 14265-44-2; iron, 7439-89-6; silicate, 12627-13-3; 12-MPA, 12026-57-2; 12-MSA, 12027-12-2; LITERATURE CITED 12-MAA, 12005-91-3. Fisk, C.; SubbaRow, Y. J. Biol. Chem. 1925, 66, 374. Crouch, S. R.; Malmstadt, H. V. Anal. Chem. 1967, 39, 1090. "Methods for Chemical Analysis of Water and Wastes"; Environmental Monitoring and Support Laboratory, United States Environmental Pro- tection Agency: Clnclnnati, OH. Johnson, K. S.; Petty, R. L. Anal. Chem. W62, 54, 1185. Ruzlcka, J.; Hansen, E. H. "Flow Injection Analysis"; Wiley-Intersci- ence: New York, 1981. Fogg, A. G.; Bsebsu, N. K. Analyst(London) 1981, 106, 1288-1295. Fujinag, T.; Okazaki, S.; Hari, T. Bunsekl Kagaku 1960, 29, 367. Adams, R. N. "Electrochemistry at Solid Electrodes"; Marcel Dekker: New York, 1969. Kircher, C. C.; Crouch, S. R. Anal. Chem. 1982, 54, 879-884. Chalmers, R. A.; Sinclair, A. Anal. Chim. Acta 1965, 33, 384. Chalmers, R. A.; Sinclair, A. G. Anal. Chim. Acta 1966, 34, 412. Tsigdinos, G. A.; Hallada, C. J. J. Less-Common Met. 1974, 36, 79-93, and references therein. Meyer, R. E.; Banta, M. C. Lantz, P. M.; Posey, F. A. J. Electroanel. Chem. 1971, 30, 345-358. RECEIVED for review January 17,1984. Accepted May 30,1984. The authors gratefully acknowledge funding for this project by the Graduate School of the University of Alabama in Birmingham through a Graduate School Faculty Research Grant. Comparison of Mass Spectrometric Methods for Trace Level Screening of Hexachlorobenzene and Trichlorophenol in Human Blood Serum and Urine Richard A. Yost* and Dean D. Fetterolf' zyxwvutsr Department of Chemistry, University of Florida, Gainesville, Florida 32611 J. Ronald Hass and Donald J. Harvan Laboratory of Molecular Biophysics, National Institute of Environmental Health Sciences, P.O. Box 12233, Research Triangle Park, North Carolina 27709 Alan F. Weston, Peggy A. Skotnicki, and Nannette M. Simon Occidental Chemical Corporation, Research Center, Grand Island, New York 14072 The comblnatlon of more seiectlve mass spectrometric tech- nlques (high-resolutlon mass spectrometry and tandem mass spectrometry-both triple quadrupole MS/MS and MIKES) with short retention time gas chromatography Is compared with conventional capillary GC/MS for the screening of human serum and urine for hexachiorobenreneand trlchiorophenoi. The various techniques are evaluated In terms of detection ilmlts, ability to obtain zero blanks, reproducibility, Ilnearity, and speed of analysis. GC/MS/MS makes possible screening at sub-part-per-billion levels 20 times more rapidly than by HRGWMS. Current address: Forensic Science Research and Training Cen- ter, FBI Academy, Quantico, VA 22135. Remedial construction at chemical landfill sites often re- quires that excavation and earthmoving occur in areas of suspected chemical contamination. Dust generated by the construction activities may contain chemicals from the site; also chemical vapors may be released if the landfill itself is penetrated. Site workers and local area residents therefore have a potential for exposure to chemicals from the landfill. The potential for exposure also exists in other chemical waste handling activities such as waste treatment and transportation. Analysis of blood and urine has been used to assess human exposure to chemicals (1,2). This study compares the utility of several mass spectrometric techniques for the screening of chlorinated organic compounds in human blood serum and urine. 0003-2700/84/0356-2223$01.50/0 0 1984 Amerlcan Chemical Society