from g r o u n d s t a t e t r a n s i t i o n s . T h e fa cilities r e q u i r e d t o p r o d u c e such plas m a s are q u i t e inexpensive; C M P sys t e m s are available a n d M I P u n i t s can be a s s e m b l e d from c o m m e r c i a l com p o n e n t s . As i n d i c a t e d above, design c h a n g e s in t h e s a m p l e i n t r o d u c t i o n s y s t e m s a p p e a r a p p r o p r i a t e for t h e al leviation of s o m e interference p r o b lems associated with t h e C M P . T h e d e m o n s t r a t e d sensitivity, selectivity, a n d universality of t h e M I P as a GC d e t e c t o r m a k e it an obvious choice over o t h e r t y p e s of selective d e t e c t o r s w i t h less universality. T h e sensitive m i c r o s a m p l e analysis capabilities of t h e M I P should also e n c o u r a g e its a d o p t i o n . Finally, t h e r e c e n t results on t h e use of t h e M I P as a multiele m e n t excitation source offer consider able p r o m i s e t h a t will surely encour age its f u r t h e r d e v e l o p m e n t .
Attention NMR Spectroscopics Tetramethylsilane, N M R grade guaranteed < 0 . 1 % total impurities downfield from T M S . Available from stock: 29200-3 Tetramethylsilane, N M R Grade 100g-$16.00; 500g-$72.00 11857-0 Hexamethyldisiloxane, N M R Grade 25g-$12.00; 100g-$21.50 N O T E : Minimum order $25.00
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References
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PCR, INCORPORATED PCR
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Ratio TLC i
Quantitation of TLC is much more accurate with an SD-3000 This d o u b l e - b e a m spectrodensitometer/ fluorometer rapidly and accurately analyzes thin layer media in all classical modes. Its background discriminating capability has made it the standard of R&D and quality control
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( 1 ) V. A. Fassel and R. N. Kniseley, Anal. Chem., 46, 1Π0Α (1974). (2) V. A. Fassel and R. N. Kniselev, ibid., pll55A. (3) G. F. Larson, V. A. Fassel, R. H. Scott, and R. N. Kniselev. ibid., 47, 238 (1975). (4) C. C. Butler, R. N. Kniselev, and V. A. Fassel, ibid., ρ 825. (5) V. A. Fassel, 0. A. Peterson, F. N. Abercrombie, and R. N. Kniselev. ibid., 48, 516(1976). (6) S. C. Brown, "Basic Data of Plasma Phvsics", MIT Press, Cambridge, Mass., 1959. (7) U. Jecht and W. Kessler, Z. Anal. Chem., 198,27 (1963). (8) U. Jecht and VV. Kessler, Z. Phvs., 178, 133(1964). (9) H. Goto, K. Hirokawa, and M. Suzuki, Fresenius Z. Anal. Chem., 225, 130 (1967). (10) S. Muravama. J. Appl. Phxs., 39, 5478 (1968). (11) M. Sermin, Analusis, 2,186(1973). (12) P.W..I.M. Boumans, F. J. DeBoer, F. J. Dahmen, H. Hoelzel. and A. Meier, Spectrochim. Acta, 30B, 449 (1975). (13) A. -J. McCormack, S. C. Tong, and W. I). Cooke, Anal. Chem., 37, 1470 (1965). (14) C. A. Bache and D. J. Lisk. ibid., ρ 1477. (15) C. A. Bache and I). J. Lisk, ibid., 38, 783(1966). (16) C. A. Bache and D.J. Li ibid., Ρ (17) C. A. Bache and D.J. Lis ibid., 39, 786(1967). (18) H. A. Move, ibid., ρ 1441. (19) J. H. Runnels and .1. H. Gibson, ibid., ρ 1398. (20) C. A. Bache and f). J. Lisk. ibid., 40, 2224 (1968). (21 ) C. A. Bache and D. J. Lisk, J. Cas Chromatogr., (1,301 (1968). (22) B. McCarrol, Rev. Sci. Instrum., 41, 279(1970). (23) C. A. Bache and D. J. Lisk, Anal. Chem., 43,950(1971). (24) F. E. Lichte and R. K. Skogerboe, ibid., 44, 1321 (1972). (25) F. E. Lichte and R. K. Skogerboe, ibid., μ 1480. (26) F. Ε. Lichte and R. K. Skogerboe, ibid., 45,399 (1973). (27) K. W. Busch and T. J. Vickers, Spectrochim. Acta, 28B, 85 (1973). (28) K. F. Fallgatter, V. Svoboda, and J. D. Winefordner, Appl. Spectrosc, 25, 347 (1971).
