RESEARCH
Arc Spectra for Water Analysis Arc speclroanalysis is useful for determining trace amounts o f metallic pollutants
m
The Origin of Oil Using lecture demonstrations, Alsoph H . Corwin of Johns Hopkins explained the presence of porphyrins in petroleum and linked their presence with the occurrence of sea squirts (ascidian) with soluble vanadium that can react with magnesium porphyrins. H e tells the Petroleum Division's Symposium on Nitrogen Compounds in Petroleum that this gives another clue to the actual origin of petroleum. disease and properdin level p r o m p t e d the laboratory to make the study to see if any relationship existed. While examining Hodgkin's disease patients for properdin levels, Levy and his coworkers included a control group of 25 persons with carcinoma. T h e researchers found 22c/c of the patients with Hodgkin's disease were low in properdin. However, in the carcinoma group about half had greatly lowered properdin levels. "Nevertheless," declares Levy, "these low values do not seem to be related to the course of the disease, the nature of the therapy b e ing used, whether chemical or x-ray, the degree to which the cancer has spread throughout the body, or to t h e site and type of carcinoma." It appears then that low properdin levels in cancer are not akin to t h e body's ability to produce the properdin it takes to keep its natural defense mechanisms. Says Levy: "Cancer patients may b e simultaneously producing a substance which interferes with the method used for measuring the serum properdin level." Hodgkin's research people are delving into this possibility now. 74
C&EN
SEPT.
2 3.
19 57
Don't overlook the d c - a r c a s a tool for water analysis. By folAnalytical lowing a few simChemistry p l e rules, a r c spectroanalysis can b e used to determine metallic pollutants dissolved in water in very small quantities. It can be used where s t a n d a r d wet methods are either extremely time consuming or even unusable, says John S. Wolfe of General Motors' Delco Products Division. F o r one thing, difficult separations of complex mixtures are usually avoided, and a single procedure can be used to detect a number of elements simultaneously. As laboratory procedures go, Wolfe points out, arc analysis is simple. T h e sample is prepared for analysis and fed into a carbon arc. T h e light given off is dispersed and t h e emission of selected wave lengths is measured. Atomic species can then b e determined and their quantity estimated. An accuracy of 209c or better is easily attained. T h e biggest disadvantage to the method, Wolfe cautions, lies in the time needed for making standards; the light from these standards is compared with that emitted b y the elements being analyzed. It is important, too, he adds, to establish methods a n d maintain conditions that will give reproducible results. To get reproducibility, electrode conditions must not change. I t is possible to make deviations a n d compromises in technique, Wolfe says, " b u t the arc absolutely refuses to tolerate inconsistency." Operations must be carried out exactly t h e same way each time an analysis is m a d e . Wolfe has used arc spectroanalysis in a survey of stream pollution in the Miami River Valley. About 200 samples were analyzed for chromium, copper, lead, zinc, cadmium, and nickel in concentrations from 0.05 to 6.0 p.p.m. and for iron from 0.05 t o 14 p.p.m. It is doubtful, h e says, if wet chemical methods could b e used at the Ar
NATIONAL MEETING
lowest concentrations and certainly the problems would have been formidable. But a r c procedures were readily a d a p t e d t o routine laboratory operation a n d were found to be adequately accurate, he told the Symposium o n Analytical Methods for Metals a n d T r e a t m e n t of Metal Wastes. Although t h e time . equired for t h e preparation of standards amounted to 50 manhours, he estimates that at least 1500 man-hours of analytical time were saved.
No Organic Thinking Allowed Inorganic chemists must f r e e their thinking from principles v a l i d only in the organic realm
m
NATIONAL
The inorganic chemist-at least
AAFETIKIG
o n e
ACS
w n o
j s dealing
with the solid state Inorganic chemistry of ionic Oiemistry compounds — must forget his organic chemistry if his approach is to be fruitful. Anton E . Van Arkel, professor of inorganic chemistry at the University
Anton E . Van Arkel, University of Leiden, explains some fundamental differences b e t w e e n organic and inorganic chemistry at t h e dinner of t h e new Division of Inorganic Chemistry. He says compounds such as TiCl 3 Br cannot b e prepared in the pure state because of halogen exchange. A mixture of various species of the type T i C l ^ ^ B r , , is obtained
