TECHNOLOGY
Guest lecturers from abroad enjoy the LSU Symposium on Modern Methods of Analytical Chemistry. R. Belcher (left), University of Birmingham (England), and Anders Ringbom, Abo Akademi (Finland), converse with M. R. Fenskc (right), Penn Stale
Impact of Ulframicrochemisfry C h e m i s t r y of single cells is next frontier to b e conq u e r e d in b i o l o g y ; n e e d m o r e sensitive instruments BATON ROUGE, L A . - T h e day may not be too distant when it will b e possible for chemists to make accurate analyses of single living cells, says Paul I. Kirk, University of California, and this development will revolutionize biological science. To work with a single cell, scientists will need instruments one hundred times more sensitive than those now used for ultramicrochemical analysis, but Kirk indicated he is developing instruments which show promise of such sensitivity. The ability to analyze single cells will be extremely important in many biological fields, for example, in tissue culture studies which Kirk is now making for the American Cancer Society. He points out that biological phenomena will be much more clearly understood when it is possible to make interpretations in terms of the chemistry of single cells. Emphasizing this point, he suggests that it should be much easier to understand t h e biochemistry of a single cell than of a whole animal. Without chemical methods applicable to the study and analysis of single cells, says Kirk, the work of analytical explorers is constant 1 y challenged. T h e impact of ultramicrochemistry on biological sciences is already apparent. Most animal experimentation requires large amounts of blood which can b e obtained without slaughter only from dogs or animals of similar size. Equivalent information, Kirk reminded, can b e obtained in many instances through ultramicrochemical techniques, 856
using tail blood from mice or rats, without killing the animals. In medicine, microanalysis has been strikingly successful in permitting pediatricians to use tiny blood samples taken from the fingers or ear lobes of infants, said Kirk, when he appeared before the LSU Analytical Symposium on Modern Methods of Analytical Chemistry. He added that ultramicrochemical methods are just as accurate for a great many purposes as ordinary chemical techniques, and they are no more difficult to teach. Alcohol Tests. Turning to his favorite subject, criminology, Kirk says police should let chemists do their analyses when testing a driver's breath for alcohol, and states should not put a definite dividing line that separates a supposedly intoxicated driver from a sober one. The National Safety Council now sets 0.15% of aclohol in a driver's blood as proof of intoxication, but a perfectly sober driver may be sent to prison on t h e basis of inadequate tests. Kirk emphasized that operation of alcohol testing devices requires expert knowledge of how the instruments work. Serious Disease. "Crime is the most serious disease of our time," says Kirk, who was recently hired to work on the much publicized Sheppard case. It kills more people than cancer or any other physical affliction. Chemical training, suggests ICirk, is essential for a successful crime investigator, because a chemist is taught t o investigate. The
best way to collect evidence, he says, is to send a good criminologist—not just any police officer—to the scene of the crime. More people today are beginning to realize the importance of trained criminologists, reported Kirk. Titration Indicators. Notable developments have taken place during the last two to three years in the field of noninstrumental quantitative analysis, says R. Belcher, University of Birmingham, England. For mercuric nitrate titrations, diphenyl carbazide sulfonic acid has been found to give sharper end points than previous indicators of this type. In Hungary, research workers have perfected 4-amino 4-methoxy diphenylamine as a redox indicator, which is particularly valuable for titrations using ascorbic acid. Basic ferric sulfate, a new acid-base indicator, can be used for titrating strong mineral acids and the stronger organic acids such as formic acid, he reported. It changes from red to a clear color at t h e end point. For titrations in the presence of ions which would bleach an inorganic indicator, this material is advantageous. Substituted benzidines, says Belcher, are providing a number of interesting indicators and precipitating agents. Dimethylnaphthadine and its sulfonic acid are excellent for the titration of zinc, cadmium, indium, and gallium with ferrocyanide; 3-methylbenzadine and 3,3-dimethylbenzadine are useful for the titration of silver with bromide or iodide, and of gold with hydroquinone. Promising reagents for the determination of tungsten in the presence of molybdenum, of selenium in the presence of tellurium, and of tellurium in the presence of selenium, have been worked out, Belcher reported. Complex Formation Titrations. The theory of chelate formation titrations can be treated in a manner similar to that used in neutralization analysis, says Anders Ringbom, Abo Akademi, Finland. Complexometric titrations with ethylenediaminetetraacetic acid and metal indicators are well suited for the analysis of extremely dilute solutions ( iO r> molar), by detecting the end point photometrically, although neutralizations and redox titrations also give good results. Reagents containing sulfur might be used as complexing agents, predicted Ringbom. Photoelectric titration, he says, can be used for precise end point detection where the titrating agents have a strength of 1 0 - 4 molar or less. With indicators giving break point absorbance curves, blank determinations are not required, and in either case the equipment needed is rather simple.
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