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The evolution of microscale equipment.

Microscale chemistry laboratory experiments have become a hot topic and are spreading across the continent. This paper is a brief trace of the history of microscale equipment and looks at where its future is headed. It also raises questions concerning the use of microscale equipment in the chemistry laboratory.

1866 - Microchemistry was being performed via a microscope with much of the area of interest being chemical analysis.'

1877 - Boricky started using the new techniques in the analysis of minerals and stones.(2)

1885 - Haushofer detailed microscopic reactions for the first time.(3)

1886 - Warburg and Ihmori developed a microbalance with a sensitiveness of 2ng.(4)

1907 - Emich and Donan reported how to make 0.2-0.5 mm diameter and 2-3 cm long capillary tubes.(5)

1908 - Bose and Conrat introduced the silver microvoltameter which was used with the Nernst microbalance whose smallest measureable weight was 0.256mg.(6)

1910 - Emich developed a micro-carius method and a micro-kjeldahl method and apparatus.(7)

1911 - Schwabe described a sedimentation tube for microchemical analysis.(8)

- Emich published a paper mentioning the use of small pycnometers.(9)

1913 - Burgess first noted the micropyrometer.(10)

- Henry announced his micromanometer.(11)

1916 - Hamburger introduced the chonohaemocrite which measured sulfate.(12)

1917 - Dubsky developed an electric furance for microelementary analysis that used a chromium-nickel wire element.(13)

- Reichard published a paper detailing the procedure for making micro-weight boats out of platinum.(14)

- Fritz Pregl announced the microcombustion tube, the microburet, the micro-electrolysis device, and the microdesiccator.(15)

1919 - Dubsky, Dingemanse, and Glatfelder announced their new form of the micro-azotometer and the microdumas. (16)

- Friedrichs developed a semi-micro fractionating column.(17)

1920 - Wertenstein introduced the differential microcalorimeter. (18)

- Taylor demonstrated an accurately controllable micropipet.(19)

1922 - Laquer announced his microextraction apparatus.(20)

1923 - Gunther Lehmann published his simple type of microelectrode that could determine pH with 1 drop of fluid.(21)

- Orient announced a flat bottom test tube whose top was a small funnel.(22)

1924 - Appelt and Hoffmeister announced the microburner for elementary microanalysis. (23)

1927 - Chamot and Mason made the following observation: "Although we Americans are probably employing these methods in industrial labs more than other nations we are publishing comparatively little upon microchemical apparatus and methods.(24)

1932 - Clarke and Hermance constructed a special electrolytic cell for microelectroanalysis. The cell was capable of separating very small quantities of metals from a few ml of solution.(25)

From this point on, not much new or modified microscale equipment was published. This may be due in part to the growing use of ground glassware, although microchemical investigations continued. This is demonstrated in a statement made by Tiedeke regarding microchemistry in the US.

"The conclusion is drawn that today the USA and especially New York is competing with Austria as the center of microchemical investigation. Germany is outClassed.(26)

1939 - Cool critiqued miemehemical kits. However, these kits were small quantities of chemicals in pasteboard boxes.(27)

1940 - Fischer debuted the micro-melting point apparatus.(28)

1989 - Bennet, Mauch, Stivers and Mellon published a paper that suggested the use of an improvised spot plate, 96 and 24 well tissue culture plates, tissue culture flasks, 1 x 12 titer strips, graduated plastic transfer pipets, thinstemmed plastic transfer pipets jumbo plastic transfer pipets and microtip pipets as microseale apparatus for high school and college chemistry labs.(29)

In the past 10 years, we have seen an explosion in the use of microscale, especially in organic chemistry. More recently microscale has reappeared in inorganic, general and high-school chemistry.

Microscale and Students

Chemistry departments in many universities have seen an increasing number of students with physical impairments taking chemistry courses. How does microscale affect them? First, let's look at the vision-impaired. Obviously a blind person needs a 'sighted' person to work with them, so microscale presents no additional problems. But for those with reduced vision it is a problem. Try to imagine seeing both a macro- and microscale distillation set-up in a 'haze' or a fog'. It becomes apparent that larger is better in this case.

Second, consider those confined in a wheelchair. People of short stature, as I am, have experienced problems with macro set-ups in organic chemistry experiments. By the time the apparatus was sufficiently mounted, one's reach was pretty well exceeded without the aid of a stool. For a person confined to a wheelchair, microscale is fantastic and allows them hands-on-experience in the lab. However, if the lab benches are lower, even then, macro equipment is accessible.

Third, consider those people with motor-skill impairment. These are students who lack the hand dexterity, similar to an arthritic hand condition. They find grasping glassware difficult: microscale for them becomes a nightmare. As can be seen, sometimes microscale is a help and in some cases it is a handicap. As more of these students enter the chemistry lab, we must consider their situation when using either micro- or macroscale equipment.

When a student is exposed to microscale only, does he miss an area of chemistry? It was a real shock when I entered industry. I had used distillation equipment with as many as 1-21 flasks. However, the smallest distillation apparatus at the industrial site was a 1,000 gallon set-up. Oddly enough, the microscale equipment looks quite similar to that apparatus. I found it necessary to use physical chemistry and learned to deal with the thermodynamics of various organic distillations. Does microscale allow the student to adequately experience these concepts? Perhaps the best approach is to offer to them both micro- and macroscale chemistry labs, so they can appreciate the problems arising from scale-up procedures.

Finally, in an age of less is better' and increasing regulations for the discarding of chemicals, are we giving the students the wrong impression of chemicals? Do they come away with a clear concept of what a particular chemical's properties are? Or do they believe that any chemical on a micro-scale is safe and any chemical on a macro-scale is not safe? These questions have no easy answer or necessarily any answer. But I challenge you to think about them each time for use micro- or macroscale equipment.

References

1. Carl J. Engelder and William Schiller J. Chem. Ed, 9 163-44, Sept 1932.

2. Engelder and Schiller.

3. Engelder and Schiller.

4. R. Cornubert, Rev. Gen- Sci, 31, 442-55, 1920.

5. F. Emich and J. Donan Mon h., 28, 825-830, 1907.

6. E. Bose and F. Conrat, Z. Elektrochem,, 14, 86-8, 1908.

7. W. Fresenius, Pure & Appl. Chem., 50, 107-112, 1978.

8. E. Schwabe, Chem Ztg., 35, 577, 1911.

9. F. Emich, Cheni, Ztg., 35, 637-9, 1911.

10. G.K. Burgess, J. Wash. Acad., 3, 7-10, 1913.

11. A. Henry, Compt. Rend., 155, 1078-80, 1913.

12. H.J. Hamburger. Proc. Acad. Sci. Amsterdam, 19, 115-25, 1916.

13. J.V. Dubsky, Schweizer Chem. Ztg., 1000, 1917.

14. C. Reichard, Pharm. Zentr., 58, 493-8, 1917.

15. Engelder & Schiller.

16. J.V. Dubsky, E Dingemanse, and A. Glattfelder, Helvetica Chimica Acta, 2, 63-75, 1919.

17. Friedrichs, A, Angew. Chem., 32, 340, 1919.

18. L. Wertenstein, J. Phys. Radium, 1 126-8, 1920.

19. C.V. Taylor, Science, 51 617-8, 1920.

20. F. Laquer, Z. Physiol. Chem., 118 215-7, 1922.

21. Gunther Lehmann, Biochem. Z., 139, 213-5, 1923.

22. I. Orient, Bul. Soc. Sc. Cluj., 1, (4), 1923.

23. E. Appelt and W. Hoffmeister, Chem. Ztg., 48,186,1924.

24. Emile M. Chamot and C.W. Mason, Chapter 17, Annual Survey of American Chemistry, July 1, 1926-July 1, 1927, ed. Clarence J. West, II (The Chemical Catalog Co.: New York, 147, 1927.

25. Chapter 8, Annual Survey of American Chemistry, ed. E.G. Zies, VIII (Carnegie Institute of Washington), 1934.

26. C. Tiedcke, Mikrochemie, 25, 65-70, 1930.

27. R.D. Cool, J Chem. Ed., 16, 28-34, 1939.

28. R. Fischer, Mikrochemie, 28, 173-82, 1940.

29. Carole A. Bennett, John J. Mauch, Fran Stivers, and E.K. Mellon, J Chem. Ed., 66, A90-1, March 1989.
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Title Annotation:microscale chemistry laboratory equipment
Author:Hathaway, Ruth A.
Publication:Canadian Chemical News
Date:Mar 1, 1991
Words:1319
Previous Article:Teaching of industrial organic chemistry.
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