An automatic system for determining the effects of temperature on the hysteresis curves of ion-selective electrodes

This paper describes an automatic system which measures the effect of temperature variations on the response of ion-selective electrodes (hysteresis curves). The system is managed by a computer program which plots hysteresis curves following a pre-established temperature cycle, from setting and controlling the temperature of the water-bath, to acquiring the response potentials of up to five electrodes after temperature stabilization.     

Measuring the effects of laboratory automation: The power of empirically derived models

Laboratory data systems are automated for a variety of scientific and management reasons. A key part to maintaining these systems is to regularly assess the impact that automation has had on the laboratory and the organization as a whole. Smith Kline Beecham R&D is using a number of different types of measurement, as well as a number of different tools, for measuring how automated laboratory systems are affecting the workflow and information flow in the laboratory. This targeted programme of metrics has increased management confidence in laboratory automation efforts, helped anticipate data processing bottlenecks, and highlighted end-user support needs.     

Application and automation of flow injection analysis (FIA) using fast responding enzyme glass electrodes to detect penicillin in fermentation broth and urea in human serum

An enzyme immobilization technique has been developed to determine the concentration of biological compounds. This technique has been applied to penicillinase and urease, which are crosslinked as very fine films directly onto the sensitive ends of pH glass electrodes, thereby dispensing with the need of an on-line enzyme reactor. The biosensor is incorporated in an FIA system within a magnetically stirred detection cell. Penicillin-V in fermentation broth and urea in human serum samples were detected and the results were compared with HPLC and spectrophotometric methods. On-line measurement is achieved through the automation of this FIA system.     

The effect of lipophilic salts on surface charge in polymeric ion-selective electrodes

The effect of quaternary ammonium salts (QAS) structure and concentration in polymeric membranes on their performance in potentiometric Ion Selective Electrodes (ISEs) without ionophore is studied. The membranes with both symmetric: tetraoctylammonium bromide (TOAB), tetradodecylammonium bromide (TDDAB), tetraoctadecylammonium bromide (TODAB), and asymmetric: tridodecylmethylammonium chloride (TDMAC) and dimethyldioctadecylammonium chloride (DODMAC) quaternary ammonium salts were tested in very broad concentration range (1–10⁻⁴%). The observed ISEs responses could not be explained within the framework of the Phase Boundary Model, but could be easily understood semi-qualitatively with help of the simple Gouy–Chapman electrical double layer theory. The latter provides a straightforward link between the electrical potential on the membrane's surface and the corresponding surface charge density. Assuming that the electrical potential difference measured in ISEs originates from adsorption of surface active ions (tetraalkylammonium cations, QA⁺) and co-adsorption of anions present in the sample, the surface charge density was calculated using the Grahame equation. We postulate that the positive charge provided by adsorption of QA⁺ at the membrane's surface provides a constant positive charge density, dependent on the QAS surface activity and concentration. This positive charge is partially neutralised by anions originating either from QAS in the membrane, or from inorganic electrolyte in the contacting aqueous phase (sample). This process could explain the dependence of electrical potential difference measured in ISEs on the concentration and type of both QAS and inorganic anions present in the sample (the latter known as “Hofmeister pattern” in potentiometry). Also the pH sensitivity of ISEs with low-QAS content membranes can be explained in the framework of the proposed model by a competition for adsorption sites on the membrane surface between QAS and high surface activity of hydroxide ions.     

Strategic planning for bioanalytical automation: managing growth successfully

Bioanalytical automation expanded at Glaxo Inc. from 1987 to 1991 by cycling through periods of justification, planning, implementation, obstacle-jumping and success, which justified continued cycling. In 1990 it became evident that the technology and its growth needed to be planned and the resources had to be managed. A Strategic Plan was researched and prepared. The plan describes the mission, values, goals and structure of the Bioanalytical Automation Group and the most important requirements for achieving those planned goals, including: (1) Long-term management commitment; (2) Trained, dedicated personnel; (3) Quality facilities; (4) Teamwork; and (5) Investment in automationcompatible equipment. The strategic plan has been in effect for over a year; current status, history, and the future are discussed in this article.     

Exchange current determination and time-dependent effects for model liquid membrane ion-selective electrodes

Exchange currents have been determined using impedance measurements on liquid membranes consisting of a solution of valinomycin in 2,3-dimethylnitrobenzene, supported on a cellulose acetate filter. Various time-dependent effects have also been investigated by the same method. This valinomycin-based membrane provides a model system for some commercial ion-selective electrodes. The results indicate that potassium ions readily cross the water/liquid membrane interface, whilst sodium ions are largely excluded from the membrane. A complex situation appears to exist, whereby a general increase in bulk membrane resistance is offset to a greater or lesser extent (depending on the cation in the contacting solutions) by a reduction in resistance of the membrane phase due to cation uptake.     

Moving up the automation S-curve: The role of the laboratory automation support function in successful pharmaceutical R&D

The political and economic climate that exists today is a challenging one for the pharmaceutical industry. To effectively compete in today''s marketplace, companies must discover and develop truly innovative medicines. The R&D organizations within these companies are under increasing pressure to hold down costs while accomplishing this mission. In this environment of level head count and operating budgets, it is imperative that laboratory management uses resources in the most effective, efficient ways possible. Investment in laboratory automation is a proven tool for doing just that.This paper looks at the strategy and tactics behind the formation and evolution of a central automation/laboratory technology support function at the Glaxo Research Institute. Staffing of the function is explained, along with operating strategy and alignment with the scientific client base. Using the S-curve model of technological progress, both the realized and potential impact on successful R&D automation and laboratory technology development are assessed.     

Interrelation of current and concentration at electrodes

A review is presented of the laws governing the relation to current density of the changes in concentration of electroactive species at the surface of an electrode. Several diverse examples are reported. Ways in which these relationships may be used to probe fluid motion are explored.This paper was presented at the Workshop on Electrodiffusion Flow Diagnostics, CHISA, Prague, August 1990.     

The laboratory of the 1990s—Planning for total automation

The analytical laboratory of the 1990s must be able to meet and accommodate the rapid evolution of modern-day technology. One such area is laboratory automation. Total automation may be seen as the coupling of computerized sample tracking, electronic documentation and data reduction with automated sample handling, preparation and analysis, resulting in a complete analytical procedure with minimal human involvement. Requirements may vary from one laboratory or facility to another, so the automation has to be flexible enough to cover a wide range of applications, and yet fit into specific niches depending on individual needs.Total automation must be planned for, well in advance, if the endeavour is to be a success. Space, laboratory layout, proper equipment, and the availability and access to necessary utilities must be taken into account. Adequate training and experience of the personnel working with the technology must also be ensured. In addition, responsibilities of installation, programming maintenance and operation have to be addressed. Proper time management and the efficient implementation and use of total automation are also crucial to successful operations.This paper provides insights into laboratory organization and requirements, as well as discussing the management issues that must be faced when automating laboratory procedures.