2223
Anal. Chem. 1904, 56,2223-2228 ~~
Table 11
sample 1
2 3 4 5 6 7 8 9
phosphate concn M FIA analysis spectrophotometric (Xa) analysis (Xb)
Xa - Xb
0.002 56 0.005 47 0.007 37 0.002 80 0.002 377 0.00301
0.001 98
0.000 99
0.001 12 0.011 06
-0.000
0.011 42
+O.OOO 61
0.01062 0.012 03 0.002 53
0.005 37
0.008 26 0.002 71 0.002 371 0.00334
+O.OOO 58 +o.ooo 10
-0.00 89 +O.OOO 08 +O.OOO 006
-0.000 33
14
LITERATURE CITED
-0.000 44
10 0.002 82 -0.000 29 0.000071 Confidence limits = 0.000071 f 0.00033 at 95% confidence level
X
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 spectrophotometric 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; 12-MAA, 12005-91-3.
=
~~
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 injection by passing them through an ion exchange column or a column filled with a chelating resin. This may be accomplished simply and should serve to remove other possibly interfering cations from the sample.
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 Protection Agency: Clnclnnati, OH. Johnson, K. S.; Petty, R. L. Anal. Chem. W62, 5 4 , 1185. Ruzlcka, J.; Hansen, E. H. "Flow Injection Analysis"; Wiley-Interscience: 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, 5 4 , 879-884. Chalmers, R. A.; Sinclair, A. Anal. Chim. Acta 1965, 33, 384. Chalmers, R. A.; Sinclair, A. G. Anal. Chim. Acta 1966, 3 4 , 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' 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 technlques (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 Center, FBI Academy, Quantico, VA 22135.
Remedial construction a t chemical landfill sites often requires 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$01.50/00 1984 Amerlcan Chemical Society
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ANALYTICAL CHEMISTRY, VOL. 56, NO. 12, OCTOBER 198
Hexachlorobenzene (HCB) and 2,4,5-trichlorophenol (TCP) were the compounds chosen for this study. They were selected as representative of two major classes of chemicals found in landfills. Hexachlorobenzene represents water-insoluble compounds which tend to migrate very slowly in the environment; 2,4,5-trichlorophenol is a water-soluble compound which will migrate more easily. Detection limit objectives for the study were set to reflect the lowest values reported previously for the compounds in physiological samples. Hexachlorobenzene has been analyzed in serum and urine by gas chromatography with electron capture detection (GC/EC) with a detection limit of 0.4 ng/mL (2). Tetra- and pentachlorophenols in urine have been analyzed as their methyl esters by GC/EC with a detection limit of 1000 ng/mL (3). The detection limit objectives for the present study were set at 0.1 ng/mL for HCB and 10 ng/mL for TCP (not necessarily specific for the 2,4,5-isomer), using a 1-mL sample. Previous techniques for trace analysis of HCB and TCP have involved GC/EC ( 2 , 3 )and gas chromatography/mass spectrometry (GC/MS) ( 4 ) . Both of these techniques lack the speed necessary for rapid screening of the large numbers of samples that is desired for monitoring landfill workers and nearby residents. This results from the extensive sample cleanup required prior to analysis as well as the time required for chromatographic analysis. Furthermore, the fats and lipids present in serum and the lipids in urine often cause interferences in the GC/EC analysis of these compounds, especially at levels close to the detection limit. In GC/EC analysis for HCB, positives were confirmed by GC/MS (2). In the present study, capillary (high-resolution) GC coupled with negative ion chemical ionization (NCI) and unit resolution mass spectrometry (HRGC/MS) was selected as a benchmark with which alternative mass spectrometric techniques could be compared. The objective of this study was to evaluate the potential of tandem mass spectrometry (MS/MS) for rapid screening of these compounds with little or no chromatographic separation. The ability of MS/MS to perform such analyses rapidly and with minimal sample cleanup has been demonstrated for drug screening in serum and urine (5)and priority pollutant screening ( 6 ) . Two different MS/MS techniques were evaluated in this study, triple-stage quadrupole MS/MS (TSQ) and mass-analyzed ion kinetic energy spectrometry (MIKES) on a reversed geometry double focusing mass spectrometer. In the TSQ analysis, NCI was employed, with samples introduced through a short microbore (50 cm X 0.1 cm i.d.) packed GC column (retention times
