X trends in analytical chemistry, vol. 2, no. 9,’ 1983

Other topics Among the forthcoming WPAC

activities which will be sponsored by FECS are the 4th Symposium on Ion Selective Electrodes, which will be held 15-17 October 1984 in Matra- hired, Hungary and the Regional Student Competitions in Analytical Chemistry.

A questionnaire has been prepared which will evaluate the status of education in analytical chemistry in

European universities. This question- naire has been distributed to all major European universities and already over 100 responses, from 15 countries, have been received. This will provide the first statistical evaluation of this field in Europe. Those who would like to receive a questionnaire are urged to contact the Secretary ofWPAC, whose address is given below. Work is proceeding towards the establishment of a system for the preparation and use

of reference materials in co-operation with European specialists in the field.

A meeting of W PAC was planned for Amsterdam on 28 August 1983 during the 9th International Symposium on Microchemical Techniques.

ROBERT KELLNER

Professor Dr Robert Kellner is Secretary of WPAC, his address is the Institute fir Analytische Chemie, Techntiche Universitiit Wtin, A1060, Wien, Getreidemarkt 9, Austria.

Analytical chemistry - good news from Ghent The Flanders Fair of Technology* was the first international gathering of its kind to be held in Flanders. Sponsored by the Flemish Government, the Fair was a show-place for what has become known as the Third Industrial Revolu- tion. It focused on three new

*The Flanders Fair of Technology was held in Ghent, Belgium 3-7 May 1983.

methodologies (biotechnology, new materials and microelectronics) which are central to this revolution. Gaston Geens, President of the Flemish Government, announced that more than 500 firms and centres of research were present and declared the Fair a great success.

One of the most interesting aspects

of the Fair was the participation of universities. The four Flemish univer- sities (Antwerp, Brussels, Ghent, Leuven) had large, 100 m* plus, stands from which they marketed their services to both industry and the public. This is a major new develop- ment in the Flemish university world. Until a few years ago, collaboration with industry was considered by many (with the possible exception of

Circle no. 033 on advertising enquiry form

trcnak L aaaIytica1 chemistry, vol. 2, no. 9,1983 XI

engineering faculties) as a distraction from the real work of the universities, namely teaching and fundamental research. The repeated reductions in university budgets made by the national government have been a prime factor in changing this attitude. In contrast to what they thought might happen, those universities which have worked with industry have found that the collaboration has stimulated the development ofnew; original products, and the provision of high quality services.

Analytical chemistry was prominent in every university exhibit, although it was not always practised by people calling themselves analytical chemists. The State University of Ghent, for instance, proposed a GLC method to

protect new azalea cultures against unlawful reproduction (Van Sumere); the Catholic University of Leuven presented RIASOF, a complete soft- ware package for the radio- immunoassay lab. (Peeters); the Uni- versity of Antwerp offered its unique combination of highly sophisticated analytical instrumentation (ion micro- scopy, the laser microprobe, the electron microprobe, spark-source mass spectrometry, etc.) for the characterization of new materials (Adams, Gijbels and Van Grieken); and the University of Brussels marketed its skills in pattern recogni- tion, an intelligent chromatograph (from yours truly) and Aquasyst, an automatic sampling and filtration apparatus for ship-based water

analysis (Polk and Steenhaut). Many other types of analytical equipment and services were also on offer.

The above list is an indication of the determination of university-based analytical chemists to renew collabora- tion between the universities and industry. It is, therefore, no surprise then that the Third Industrial Revolu- tion Council of Flanders is headed by an analytical chemist, Prof. J. Hoste, Director of the Laboratory of Analyti- cal Chemistry of the University of Ghent.

D. L. MASSART

D. L. Massart is Professor of Analytical Chnistsy in th Free University of Brussels, Belgium. He is an advisory editor for TrAC.

OBSERVER -topics of interest in the current literature

A releasable label for immunoassay by anodic stripping voltammetry

from Matthew J. Doyle, H. Brian Halsall and William R. Heineman

Immunoassay is a very powerful analytical tool that is commonly employed clinically to diagnose a variety of physiological conditions’. Radioimmunoassay, which uses a radioactive label, is the predominant method. Numerous assays based on non-radioactive labels have been developed in order to avoid problems

All HSA

Ab +

associated with isotopic labels2. We are developing immunoassay techniques that use electroanalytical methods, such as voltammetry and amper- ometry for detection ofan electroactive label3 or of an electroactive product generated by an enzyme labe14.

The label described here is a metal ion which can be released after equilibration with antibody and sub- sequently determined by anodic strip- ping voltammetry. This label has been

All HSA (DTPA-ln3+)x Ab:HSA

Ab on Free antigen and immunoadsorbent

Sound antigen and bound labelled-antigen labelled-antigen

Fig. I. Immunoassay based on competition between label/cd HSA (DTPA-In’+) and native antigen, HSA for a limitcd number of antibody sites insolubilized on immunoadcorbent.

$$(DTP A-ln3+)x -% $zE(DPTA)x + xW

Fig. 2. Release of ii *+ label by acidzfxation.

0165-9936/83/$01.00

used in an immunoassay for human serum albumin (HSA)‘,“. The metal ion label is tightly bound to HSA by means of the chelating agent diethylenetriaminepenta-acetic acid (DTPA), which is covalently attached to the (Y and E amino residues of HSA via one of the carboxylic acid groups; there are about 3 DPTA groups to every HSA molecule.

In3+ was chosen as the metal ion label for several reasons. In3+ is very tightly bound by DTPA (Kf = 102’), making the labelled protein complex stable until the In3+ is released by acidification; In3+ is not normally found at detectable levels in biological tissues and fluids, which minimizes possible interference from background levels of the label in sample matrices; In3+ exhibits a characteristic reversible electrochemical behavior in complex- ing media.

The immunoassay is based on the competition between labelled, HSA (DTPA-InS+)X, and native antigen, HSA, for a limited number of antibody binding sites, which have been insol- ubilized on an immunoadsorbent (I-Ab), as depicted in the reaction scheme in Fig. 1 (the equilibrium is not written stoichiometrically).

Following equilibration, the anti- body ‘bound’ complexes are separated, as a pellet, from excess ‘free’ antigen by centrifugation. The In3+ label is then

@ 1983 Elsevier Scicnv Publishers B.V.