The anisotropy (ACT) of the lg5Pt chemical shielding for two Ptlv complexes, [( Me),Pt(acetyla~etonato)]~ and [Me,Pt],S0,.4H20, measured by H-lg5Pt cross-polarization techniques, is found to be of the order of 103 p.p.m. and hence of such a magnitude that a significant contribution of chemical-shift anisotropy relaxation to the I95Pt solution-state relaxation parameters Tl and T2 is evident at high magnetic fields.

A liquid chromatographic method has been developed for the determination of free fatty acids in butter. The fatty acids are converted to the p-bromophenacyl esters, via a crown ether-catalyzed reaction, without separation from the other butter components. The esters are separated on a Cis-bonded silica column by using an acetonitrile-water solvent gradient and quantitated using the ester of heptadecanoic acid as internal standard. Cu, and C ,S:i co-elute in the acetonitrile-water system but are separated using an isocratic methanol-acetonitrile-water system. Limits of detection range from 7 ng for butyric acid to 45 ng for linoleic acid. The average coefficient of variation (n = 10) for 10 free fatty acids from,a butter was 5.83%.

In order to assess some of the residue characteristics of the experimental carbamate acaricide, 3‐methyl‐5‐isopropylphenyl‐N‐(n‐butanoyl‐)‐N‐methylcarbamate (promacyl) a 0.2 % aqueous emulsion was applied to cattle in a series of five trials and in a sixth, the technical product was added to the feed of stalled cattle.A method of analysis involving the formation of a derivative suitable for gas chromatographic analysis on electron capture detection mode was developed.Separate estimations of levels of the parent compound and the metabolites, 3‐methyl‐5‐isopropylphenyl ‐N‐methylcarbamate and 3‐methyl‐5‐ isopropylphenol, were carried out on fatty tissues and butterfat but for non‐fatty tissues “total” levels, which were a combined estimate of 3‐methyl‐5‐isopropylphenol itself and all substances hydrolysable to it, were estimated and quoted as Promacyl.The highest group average level of the parent compound was 0.9 part/million in fatty tissues 24 h after the last of 8 applications at 3 day intervals. In a single spray trial the maximum group average of 0.7 part/million in fatty tissues 24 h after treatment fell to 0.2 part/million after 5 days.Residues in butterfat, 7 h after a single dermal application showed a maximum level of 1.2 parts/million and this declined to 0.1 part/million on the seventh day after treatment.“Total” residues in non‐fatty tissues were of the order of 1/10 those found in fatty tissues.

The Changing Demands on the AnalystThe professional mission of analytical chemists is to supply clients with information about the composition of samples. The means for gaining this information has changed profoundly over the years, from the common use of "wet" chemical methods to the almost complete reliance on physical instrumentation that is found in contemporary laboratories. Such changes have been made largely in response to the more stringent demands made by clients, for example, requests for the determination of very low levels of analyte or for fast multielement analysis.Inevitably, the shift to instrumental methods has also required analysts to augment their training in chemistry with an understanding of other fields such as electronics, optics, electromagnetism, and computing. However, the need to develop knowledge and skills in these diverse disciplines should not be allowed to obscure the distinctive task of the analyst: to supply chemical information about samples. The emphasis should be kept on gathering reliable information, rather than being shifted to any particular technique or methodology.The Evolving Concept of Information It would be useful and timely for analysts to reconsider in greater depth what is meant by "information" in general and "chemical information" in particular. Then their complex and rapidly evolving methodologies could be put in broader teleological perspective.Such matters have been the subject of much study since a theory of information was developed by Claude Shannon in the late 1940's to solve some problems in message communication over the primitive Morse Code transmitters then in use (J). The theory has been applied to a varied range of situations that involve the transmission of "mes-sages", where the term message is used in its widest sense. This range includes the faint molecular messages that emanate from the analyte in a sample, then pass through the electronic encoding and decoding processes of a spectrometer.

No abstract