DUO-
Beckman Instrumentation
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Figure 6. Bar chart showing commercial life-span of Beckman spectrophotometers either 5 or 12.5 s. Heated gas cells were used for sampling, since the prin cipal purpose of the system was for analyzing eluted fractions from a gas chromatograph. Although the IR-102 did not enjoy a long or prosperous life because of sensitivity limitations, it paved the way for more conventional spectrophotometers utilizing the vari able filter. Major credit for the IR-102 and its immediate offspring goes to G. T. Keahl who also spearheaded devel opment of IR-4 and IR-5 successors. Microspec. A double-beam counter part of the IR-102 was introduced in February 1966 as a low-cost spectro photometer. Designated the "Micros pec", this instrument was comparable to the IR-5 in performance. T h e name "Microspec" alluded to the small beam size at the sample site which al lowed micro specimens to be analyzed on a routine basis (38). IR-33. Although the Microspec per formed as expected, the infrared field had grown accustomed to the high res olution afforded by gratings. In recog nition of this, a grating used in two or ders was added to the basic Microspec system, thus providing a high-perfor mance, double-beam spectrophotome ter at a reasonably low price. This unit was designated the IR-33 and became the forerunner of the AccuLab family of spectrophotometers still in produc tion, all utilizing a rotating wedge fil ter in conjunction with a grating. In the 35 years spanned by these in struments (Figure 6), the spectropho tometer has become a commonplace laboratory tool. T h e vacuum tube which ushered in many of the marvels of instrumentation is now obsolete. Prism dispersers are used only in spe
CIRCLE 65 ON READER SERVICE CARD 296 A · ANALYTICAL CHEMISTRY, VOL. 4 9 , NO. 3, MARCH
1977
cial applications. T h e grating and mi croprocessor now dominate the com mercial spectrophotometer field while the interferometer and tuned laser gain devotees. In time, even these ap proaches may be replaced in the search for the most economic solution for the analyst's needs. Acknowledgment T h e authors appreciate the many interviews with participants in this story. Special thanks go to Duane Fos ter who has been concerned with the manufacture of all the instruments de scribed here. References (la) R. H. Millier, Ind. Eng. Chem. Anal. Ed., 11,1 (1939). (lb) R. H. Millier, ibid., 12, 571 (1940). (le) R. H. MUller, ibid., 13, 667 (1941). (2) A. C. Hardy, J. Opt. Soc. Am., 28, 360 (1938). (3) R. A. Morton and I. M. Heilbron, Riochem.J., 22,987 (1928). (4a) R. L. McFarlan, J. W. Reddie, and E. C. Merrill, Ind. Eng. Chem. Anal. Ed., 9,324(1937). (4b) A. E. Parker and B. L. Oser, ibid., 13, 260(1941). (4c) B. Demarest, ibid., ρ 374. (5) T. R. Hogness, F. P. Zschiele, Jr., and A. E. Sidewell, Jr., J. Phys. Chem., 4 1 , 379 (1937). (6) H. H. Cary and A. O. Beckman, J. Opt. Soc. Am., 31,682(1941). (7) H. H. Cary and W. P. Baxter, U.S. P a t ent 2,463,743 (Dec. 29, 1945). (8) K. Morgareidge, Ind. Eng. Chem. Anal. Ed., 14,700(1942). (9) P. T. Gilbert, Jr., R. C. Hawes, and A. O. Beckman, Anal. Chem., 22, 772 (1950). (10) P. T. Gilbert, Jr., U.S. P a t e n t 2,714,833 (Apr. 19, 1950). (11) M. L. Greenough, W. E. Williams, and J. K. Tavlor, Rev. Sci. Instrum., 22, 484 (1951). (12) Anal, Chem., 36, 127A (1964).
