January, 1980 CONFERENCES AND COURSES 33 Scottish Region Meeting The Scottish Region, together with the Chromatography and Electrophoresis and Joint Pharm- aceutical Analysis Groups and the Association of Clinical Biochemists, will be holding a Meeting on February 20th, 1980, entitled “Advances in Applied High-performance Liquid Chromatography” (see Analytical Division Diary for details). Among the invited speakers from abroad will be Professor J. F. K. Huber and Professor R. W. Frei; some notes on Professor Frei’s career and research work follow. Biography R. W. Frei was born in 1936 in Geneva, and took his Diploma in Chemistry in Switzerland. Later, in 1965, he was awarded a PhD in Analytical Chemistry in the USA. Following postdoctoral work with D. E. Ryan a t Dalhousie University, Halifax, Canada, he was appinted Assistant Professor in 1966 and Associate Professor in 1969 at the same University.From 1972 to 1977 he was head of analytical research at Sandoz Ltd., in Basle, and since 1977 he has been Professor and Head of the Department of Analytical Chemistry at the Free University of Amsterdam. Professor Frei has research interests in the physical separation sciences, spectroscopy and electrochemistry as analytical tools for deter- mining organic pollutants and pharmaceutically active compounds. He is Editor of the International Journal of Environmental Analytical Chemistry and the Journal of Toxicological and Environmental Chemistry Reviews and an Editorial Board member of the Journal of Liquid Chromato-34 SCOTTISH REGION MEETING Anal.Proc. graphy. Professor Frei is also author or co- author of about 150 scientific publications including several books and reviews in various fields of analytical chemistry. Research Current research activities are centred around the topic of selective sample handling and detection. Reaction detectors are of prime interest and several projects are in progress. Reaction Detectors Fluorescamine - aniline reaction detector The reaction of aminophenols and various substituted chloroanilines with fluorescamine to form fluorescent derivatives is being studied. For chloroanilines, which are interesting from a persistent pollutant point of view, the reaction works well, with reaction times of up to 1 min. Besides being relevant as a selective and sensi- tive detection technique it serves conveniently as a model system for the study of band- broadening effects in the tubular reactor designs used for this investigation. The aim is to use this very selective detection principle for the trace determination of important substituted aniline pollutants in waters or biological matrices.Extraction detectors based on ion-pairing principle This development is based on a dynamic micro-extraction principle for fluorescent ion- pairs. The basis is the ion-pair formation between tertiary amines (drugs, pesticides or their metabolites) and the highly fluorescent dimethoxyanthracene sulphonate (DAS) . The ion-pair, which is formed immediately after leaving the column, is extracted into the organic phase of a segmented continuous-flow system and detected in a fluorescence detector.Band broadening in such an extraction detector is found to be primarily caused by the phase separator. Other band broadening phenomena are suppressed by segmenting the flow with air bubbles and/or immiscible organic solvents. A critical study of the effect of various reactor designs, mixing Ts, extraction spiral dimensions, phase separators and the miniaturisation of these units on band broaden- ing is being carried out. Air and solvent segmentation systems are also being compared. Interesting modifications of this approach are normal-phase separation on silica gel instead of reversed-phase separation and the use of the mobile phase, viz., chloroform, as the extraction medium. Photochemical reaction detectors The principle involves the use of post-column and on-line photochemical reactors to either catalyse another continuing reaction (i.e., hydrolysis, redox) or to induce new reactions with or without reagent addition.The detec- tion signals (ultraviolet - visible, fluorescence or electroanalytical) of the resulting products can then be used for a more selective and sensitive determination of suitable compounds separated by HPLC. An air-cooled xenon lamp reactor has been designed. The first successful tests were carried out with the drug clobazam, which is converted to highly fluorescent derivatives upon irradiation. The influence of reactor design on band broadening and the feasibility of using segmen- tation techniques for longer photochemical reactions is being studied.Pre-concentration and Selective Sample Handling This work is based on earlier observations that compounds of relatively low polarity are retained completely on the hydrophobic surface of chemically bonded reversed-phase (C18) materials. Dibutyl phthalate (DBP) and di-2- ethylhexyl phthalate (DEHP), which are widely used as softeners in plastics, have been studied, and pre-column techniques that permit collec- tion of up to 1-1 water samples on 2-mm long pre-columns containing 5- pm particles of C,, material developed. Following the on-line transfer of sample and step gradient separation it is possible to determine concentrations of these phthalates in the 0.1 p.p.b. range with good recovery and reproducibility. Adsorption - desorption phenomena, loading capacity, re- coveries, lifetime and performance of pre- columns as a function of different particle sizes and qualities of support materials, sampling flow-rates, pre-column construction and other parameters are being investigated.Concentra- tion factors of up to 10 000-fold can be obtained with this technique. The principle has been successfully extended to other pollutants, such as PCB’s and chloroanilines, with the idea of coupling pre-concentration techniques of chloro- anilines with the fluorescamine post-column reaction detector. In addition to trace enrichment the pre- column concept can serve other functions, such as selective sample clean-up, possibly via on- column reactions, protection of the separation column, field sampling and automatic sample handling.Several of these aspects have been investigated with drugs and pesticides.January, 1980 SCOTTISH REGION MEETING 35 The concept of pre-concentration on hydro- phobic surfaces can also be used in analogy for relatively polar compounds on polar surfaces. This idea is being studied for the urea herbicides metoxuron, linuron and diuron, again with the purpose of clean-up and trace enrichment and as an approach to residue analysis of these species. In addition, an on-column catalytic hydrolysis on silica gel can be used to hydrolyse rapidly and selectively these ureas to the corresponding anilines for derivatisation purposes. The anilines are then derivatised in a pre-column or post-column mode to yield derivatives with good detection properties for liquid chromatography (fluorescamine reaction) or for gas chromatography (fluoro derivatives for electron-capture detection).Development of Polarographic Detectors for HPLC A study of the design and development of mercury drop detectors for dynamic flow systems is being undertaken. The first version has as new features a horizontally placed mercury capillary and a pin moveable against the capillary opening in order to reduce dropping time. In the meantime two further improved designs have also been developed. The mercury capillary and the reference electrode now have a conical outlet, which permits a better seal, further miniaturisation for low dead volume designs and the reduction of drop size without the moveable pin. A new approach to measuring time constants and response volumes for such detectors has been proposed.The electrochemical detectors tested, while being complementary to other HPLC detectors, show a reproducibility and sensitivity at least comparable with a good ultraviolet detector. The selectivity, the response time and the linear dynamic range are better for optimally designed electroanalytical cells. Finally, a fourth version is now being con- structed, which permits the use of pulsed techniques. The improvement in noise, detec- tion limit and over-all performance is being tested. These detectors are partly applied in conjunction with suitable chemical reactions in a pre- or post-column mode. A recent applica- tion is described below. Application to selective detection of organo- sulphur compounds The studies are based on complexation phenomena of selected organosulphur com- pounds with the mercury surface of our DME detector.The over-all reaction is as follows Hgo + 2 Th -+ Hg(Th)22+ + 2e (Th = thiourea compound) The resulting electrical current is proportional to the concentration of Th. The unusual aspect of this detection mode is the use of the anodic range of the mercury electrode. All of the sulphur compounds tested that contain a thio- carbonyl group can be detected at a potential of about + 180 mV. The removal of oxygen is not necessary. The major advantage of our DME detector, aside from being simple and of low cost, is the selectivity, which permits the determination of such compounds in a complex matix with a minimum of sample handling. As an example, ethylenethiourea was determined directly in urine samples. More fundamental work on the actual complexation phenomena a t the mercury surface is in process. Room- temperature Phosphorimetry and its Analytical Potential Phosphorescence has for a long time been assumed to be usually only observable under low-temperature conditions (77 K). This has been one of the main reasons for its neglect up to now, particularly within analytical chemistry. In this project we have begun systematically to explore the possibilities of measuring phosphorescence under room-temperature conditions and to study parameters such as internal and external heavy atom effects, the nature of the solvent (its viscosity and oxygen content) and their effect on phosphorescence at room temperature and on life times.