impact or N p charge exchange spectra of the same compound. The spectra obtained with He NO, Na NO, and Ar NO mixtures were very similar. The abundant M + H ions observed in some of the spectra are attributed to water impurities in the charge exchange reagents. The technique of NO/N2 charge exchange has been successful in enhancing abundances of M + ions of several other compounds whose electron impact mass spectra (as TMS derivatives) show little or no molecular ions. These compounds include the per-TMS derivatives of methyl lithocholate, methyl cholate, the methyl ester of 6-bromo2-naphthylglucuronide, guanosine, and P-glycerolphosphate. Pure NO has been used previously as a reagent gas (9, 13), but the lifetimes of conventional filaments are short. With these mixtures of nitric oxide and common GC carrier gases, no deleterious effects were noted on the samples of hot wire filaments. It is projected that the conventional carrier gases will be used in the gas chromatograph and that NO will be added in the low pressure region of the inlet lines to the mass spectrometer. It is hoped that NO (Ar NO or He + NO) mixtures will these Wp prove to be analytically useful for other types of compounds that give low intensity or non-existent molecular ions in other mass spectrometric techniques.
+
+
370
'
?-
i
, 255
I
47%
Y
550
i "/L
Figure 3. Charge exchange spectrum of the per-TMS ether of
methyl chenodeoxycholate with N z / N O mixture Reagent pressure 0 8 Torr (6 1% NO) and source temperature 21 0 "C
+
proved to be the reagent system that gave the desired results of enhancement of molecular ions and retention of the major fragment ions. Figure 3 shows the nitrogen/ nitric oxide charge exchange spectrum of the trimethylsilyl ether of methyl chenodeoxycholate. In all of the N 4 N O charge exchange spectra, there is an enhancement of molecular ions, retention of the major fragment ions, and loss of the extensive fragmentation observed in the electron
+
+
Received for review October 10, 1973. Accepted December 5 , 1973. This work was supported in part by a grant from the National Science Foundation, G P 20231. (13) D F Hunt and J F Ryan I l l , Chem C o m m u n , 620 (1972)
Liquid Coal Compositional Analysis by Mass Spectrometry J . T. Swansiger, F. E. Dickson, and H.T. Best Gulf Research & Development Company. Pittsburgh. Pa. 75230
With the increasing emphasis on the efficient use of existing energy resources which do not adversely affect the environment, liquid products derived from coal appear very promising as a possible liquid fuel source (1-3). A typical coal liquefaction process normally employs a solvent system that promotes depolymerization and hydrogenation of the coal which results in a fuel with enhanced heat content and reduced sulfur content. The coal liquids used in this work were produced by a bench-scale pilot plant employing a catalytic hydrogenation process. The feed coal is ground and slurried with a solvent derived by recycling part of the product. The feed slurry is combined with hydrogen, heated, and passed through a catalytic reactor of proprietary design. The reactor product goes to a gas-liquids separator where hydrogen is recovered for recycle. The liquid product goes to a solids separator where ash and undissolved coal are removed ( 4 ) . (1) Hydrocarbon Research, lnc., Project H-Coal Report on Process Development, Report PB 173765, Clearinghouse Federal Scientific Technique Information. Springfield, Va. (2) Spencer Chemical Division, Solvent Processing of Coal to a Deashed Product, August 1962 to February 1965, R&D Report No. 9, OCR, Washington, D.C. (3) 1973 Annual Report of the Office of Coal Research, Clean Energy from Coal-A National Priority, U.S. Government Printing Office, Washington, D.C., pp 67-75. ( 4 ) H. G. Mcllvried, S W. Chun, and D . C. Cronauer. unpublished data
730
ANALYTICAL CHEMISTRY, VOL. 46, NO. 6 , M A Y 1974
Techniques for the compositional analysis of coal liquids have become of importance in order to optimize operating parameters and monitor reaction products. Other workers have applied mass spectrometry to the study of coal (5, 6), coal extracts ( 7 ) , coal tars ( B ) , and oils derived from coal ( 9 ) , primarily using existing group-type methods developed for petroleum analysis (10, 11) and low ionizing voltage techniques (12) to obtain a carbon number distribution. Sharkey, Shultz, and Friedel have indicated (13) that two type analysis methods for analyzing aromatics in petroleum (14, 15) are not directly applicable to coal hy( 5 ) H . W . Holden and J . C. Robb. Fuei. 39, 39 (1960). (6) A. G. Sharkey. Jr., J L. Shultz. and R. A Friedel. "Advances in Coal Spectrometry, Mass Spectrometry," Washington, U.S. Department of the Interior. Bureau of Mines, 1963. (7) T Kessler. R. Raymond, and A. G. Sharkey. Jr., Fuel. 48, 179 (1969). (8) J L. Shultz. R. A. Friedel, and A. G. Sharkey, Jr , "Mass Spectrometric Analyses of Coal-Tar Distillates and Residues," Washington. U.S Department of the Interior. Bureau of Mines, 1967 (9) A G. Sharkey. Jr., J . L. Shultz, and R. A. Friedel, Fuel. 41, 359 ( 1962). (10) R . J . Clerc, A. Hood. and M . J . O'Neal. A n a / Chem , 27, 868 (1955). (11) G. F. Crableand N . D . Coggeshall.Ana/. Chem.. 30, 311 (1958) (12) H E. Lumpkin, Ana/ Chem 30. 321 (1958). (13) A. G. Sharkey, Jr , J . L Shultz, and R A. Friedel. "Analytical Methods in Mass Spectrometry." Washington, U.S. Department of the Interior, Bureau of Mines, 1967.
T a b l e I. Characteristic Ions for Group Sums in Matrix Characteristic ions
Z No.
251, 252, 265; 266, 279, 280 227, 228, 241, 242, 255, 256 211, 212, 225, 226, 239, 240 193, 194, 207, 208, 221, 222, 235, 236 205, 206, 219, 220, 233, 234 201, 202, 215, 216, 229, 230, 243, 244, 257, 258, 271, 272 189, 190, 203, 204, 217, 218, 231, 232, 245, 246, 259, 260 185, 186, 199, 200, 213, 214 183, 184, 197, 198 181, 182, 195, 196, 209, 210, 223, 224 177, 178, 191, 192 165, 166, 179, 180 153, 154, 167, 168 103, 104, 117, 118, 131, 132, 145, 146 129, 130, 157, 158, 171, 172 128, 141, 142, 155, 156, 169, 170 77, 78, 79, 91, 92, 105, 106, 119, 120
- 28
Type
Benzopyrenes C hrysenes Decahydropyrenes Hexahydrop yrenes Tetrahydrofluoranthenes P yrenes/Fluoranthenes Dihydropyrenes Octahydrophenanthrenes Hexahydrophenanthrenes Tetrahydrophenanthrenes Phenanthrenes Fluorenes IDihydrophenanthrenes Acenaphthenes/Biphenyls/Dibenzofuran
Tetralins/Benzofuran Tetrahy droacenaphthenes Naphthalenes Benzenes
drogenation products (coal liquids). Sharkey e t al. (16) have analyzed liquid products from coal hydrogenation using modified forms of published type analyses designed for petroleum. The more recently introduced RobinsonCook analysis for aromatic hydrocarbon in the gas oil range (17) appeared to produce serious errors (compared to low voltage data) when applied to coal liquids. Our experiments indicated that the petroleum grouptype methods do not contain the proper calibration standards to accurately analyze coal liquids. Also, the short chain alkyl substitution of coal liquids allowed a new analytical matrix to be developed. Analysis of the saturate fraction was not pursued since this fraction normally constitutes 5%) interfere in the analysis. Thus, independent analysis of the aromatic fraction was necessitated by the unknown .amount of resins which vaporize into the spectrometer system. The analysis of a coal liquid aromatic fraction derived from a Big Horn sub-bituminous coal is shown in Table V. Originally, it was intended to include three phenolic types in the analytical matrix. Distillate samples (200 “C) containing
