Liver, Horseradish and Bananas: a Diet of Enzymes for Voltammetry

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infrared data were correlated to the physical properties of the chemically ... PAS) is a near-surface analysis technique
ANALYTICAL PROCEEDINGS. JUNE 1989. VOL 26 under various conditions, were also studied by FTIR - PAS. The infrared data were correlated to the physical properties of the chemically modified cotton fabrics. C4. APPLICATIONS OF FTlR PHOTOACOUSTIC SPECTROSCOPY TO THE NEAR-SURFACE ANALYSIS OF POLYMERIC MATERIALS Charles Q. Yang, Department of Chemistry, Marshall University, Huntingdon, WV 25701, USA Fourier transform infrared photoacoustic spectroscopy (FTIR PAS) is a near-surface analysis technique, because in a PAS experiment only the infrared radiation absorbed within the first thermal diffusion length from a sample’s surface can generate photoacoustic signals. As the thermal diffusion length is inversely proportional t o the square root of the mirror velocity, the sampling depth can be changed by varying the mirror velocity of the interferometer and depth profiling can be performed. In this research, FTlR - PAS is evaluated as a near-surface analysis technique for various polymeric fibres and films. For example, when a polypropylene fibre treated with an ester - polyether copolymer was examined with both PAS and KBR pellet techniques, the carbonyl band from the copolymer finish was observed only in the photoacoustic infrared spectra. It was found that the bands due t o the near-surface species in the photoacoustic spectra were much stronger than those i n the diffuse reflectance infrared spectra. The depth profiling and quantitative near-surface analysis using FTlR - PAS were also evaluated. The photoacoustic infrared date of polymeric films also demonstrate that FTlR - PAS is a useful technique for near-surface analysis. C5. APPLICATION OF A SILICA-IMMOBILISED LIGAND BEARING THIOETHER SULPHUR AND NITROGEN DONATING ATOMS AS A SORBENT FOR PRECIOUS METAL IONS T. Seshadri and H.-J. Haupt, Department of Chemistry, University of Paderborn, Warburger Str. 100, 4790 Paderborn, FRG The reaction of silica gel with the synthesised silanes, 2-(trimet hoxysi Iy let hy It h io)aniI ine (TS-SPY) and 3 4t rimet hoxysilylpropyl-2-thioethy1)pyridineproduces the modified ligand - silicas SIL-Spy and SIL-SNH2, respectively. SIL-Spy, for example, exhibits a capacity of 0.95 m m o l 9-1 for gold(l1l) and for other precious metals i n the range 0.5-0.82 m m o l g-1 except rhodium(lll), and no affinity for base metals in acidic conditions. Separation of Pd(l1) from large amounts of less precious metals, Rh(lll), Ir(lll), Ir(lV), as well as Ir(lll) from Rh(lll), is possible under column conditions on SIL-SPY. A quantitative elution of Pd(ll) is effected with acidic 5% thiourea solution. Distribution coefficients are presented to establish the selectivity of SIL-Spy for precious metals. Furthermore, the ligand - silane complexes (TSSNH2)2PdC12and (TS-SPy)PdCI2 have been prepared and compared with their silica-bound counterparts. C6. DETERMINATION OF NON-REMOVABLE CONTAMINATION ON SOME STAINLESS STEELS A. Belfiore, G. Panciatici and M . Poggianti, Centro Ricerche Esperienze Studi Applicazioni Militari, San Piero a Grado, Pisa, Italy The 300 series stainless steels are extensively used in the nuclear industry; however, during routine operations or by accidental means they can be contaminated. The contaminating radionuclides bind to their surfaces with t w o groups of bonds, the first defined as a physical bond with an easily removable contamination, the second defined as a chemical bond with a more strongly held contamination. The evaluation of contamination present on surfaces with the widely used smear test technique permits a very rough determination of radionuclides held by physical bonds, while it does not allow valuation of the ones held by chemical bonds (so-called non-removable contamination). An analytical procedure that permits the extraction of contaminants held to surfaces with the two kind of bonds (physical and chemical) separately has been set up at our laboratory. Stainless steels AlSl 302, 304, 316 have been artificially contaminated with a solution of l37Cs, 90Sr and 6OCo in conformity with a model adherent to a real contamination, pouring o n the surfaces an aliquot of each contaminant solution and allowing evaporation. The influence of steel alloy components and of the time elapsed from contamination of surfaces on relative non-removable bond percentages has also been investigated.

20 1 C7. A N INVESTIGATION OF CHEMILUMINESCENCE REACTION IN LUMINOL - IODINE - ARSENIC(II1) SYSTEM Li Shuling and He Yinglu, Institute of Rock and Mineral Analysis, Academy of Geological Science, Beijing, P. R. China In accordance w i t h Marsh’s principle, i.e., l2 reacts with AsH3 quantitatively, the amount of Ass+ is determined by the method that detects remaining l2 using the luminol - l2 - As3+ chemiluminescence reaction. The detection limit o f this method is 9.8 x I 0 l o g m l - I of As3+.The relative standard deviation is 4% of 1.0 x 10 -9 g ml-1 of As3+. This method is of high sensitivity and good selectivity. The following elements d o not interfere in the determination of 40 p.p.b. of As3+: 4 m g of Ca2+, Mg2+, Fe3+, 2 m g of AP+, 1 m g of Co2+, Ni2+, 0.6 m g of Gel”, 0.5 m g of C U ~ + , Mnl, 0.1 m g of Pbz’, Znz‘, 0.2 m g of WVI, MoV1,0.05 m g of SntV, 0.02 m g of Selv, Telv, Hg2+, Ag+, Pdll, 0.01 m g of Sblll, 20 m g of SO& and 5 m g of NO3-. The detection limit of this system can be halved by addition of the surfactant Brij35. The results determining the As3’ contents of ores are satisfactory. C8. APPLICATION OF THERMOGRAVIMETRIC ANALYSER (TGA) TO THE DETERMINATION OF DIFFUSION COEFFICIENT AND WATER CONTENT Toshio Ogawa, Kanazawa Institute of Technology, 7-I, Ohgigaoka Nonoichi lshikawa 921, Japan Thermograms in TGA are usually recorded as a function of temperature in a given atmosphere. In this study, some procedures were applied t o a TGA instrument so as t o determine diffusion coefficient, which was the value for water i n a polymer film a t constant temperature. The result was satisfactory. This technique is very simple and easy for obtaining the diffusion coefficient compared with conventional methods. Further, the water content of a polymer film was also easily determined by this method without any thermal degradation. D1. APPLICATION OF GLASSY CARBON AND MODIFIED GLASSY CARBON IN ANALYTICAL CHEMISTRY B. Vukurovic and M. LauSevic, University of Belgrade, Faculty of Technology and Metallurgy, Belgrade, Yugoslavia, Z. LauSevic, The Institute of Nuclear Science ”Boris Kidrit, ’’ VinCa, Belgrade, Yugoslavia, M. Rajkovic, University of Belgrade, Faculty of Agriculture, Zemun, Yugoslavia Owing to its chemical inertness, good electrical conductivity and temperature resistance, glassy carbon (GC) can be used as an electrode material resistant to corrosive media over a wide temperature range. Such an electrode can operate in a considerably wider potential range than a platinum or mercury electrode. In this paper w e present our investigation into the preparation of GC and modified GC electrodes for electroanalytical use. The starting material was home-made GC. Modification of GC electrodes has been performed b y mixing copper powder and/or copper compounds w i t h phenol formaldehyde resin before carbonisation. XPS and AES measurements, combined with cyclic voltammetry testing, showed that the properties of modified GC samples were very similar to those of copper wire. The GC and modified GC electrodes, produced in our laboratory, have been tested in various potentiometric titrations. The results of these titrations were in good agreement with the results obtained by using a glass electrode, a platinum wire or a copper EDWlSEl electrode (versus SCE), showing that GC and modified GC can be successfully used i n analytical chemistry.

Reference 1.

VuEurovic, B., and Rajkovic, M., Analyst, 1987, 112, 539.

D2. LIVER, HORSERADISH AND BANANAS: A DIETOF ENZYMES FOR VOLTAMMETRY Malcolm R. Smyth *, Michelle Connor*, Pilar Dominguezt, Jose Maria Fernandez”, Richard O’Kennedy#, Joseph WangS and Paulino Tunon Blancot, * School of Chemical Sciences, Dublin City University, Glasnevin, Dublin 9, Ireland, tDepartment of Chemistry, University of Oviedo, Oviedo, Spain, #School of Biological Sciences, Dublin City University, Glasnevin, Dublin 9, Ireland, §Department of Chemistry, State University of New Mexico, Las Cruces, N M 88003, USA Analytical voltammetry has progressed in recent years mainly as a result of improvements made with respect to important analytical parameters such as sensitivity and selectivity. Improvements in sensitivity have come about through the application of stripping voltammetric techniques, whereas improvements in

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302 selectivity have arisen mainly f r o m the development of electrochemical detection systems for use with high-performance liquid chromatography. A major area of research in voltammetry is n o w centred around the use of biological molecules t o improve the sensitivity and selectivity of analytical voltammetric methods further. The molecules that have been most used in this regard are immunoglobulins and enzymes. In this paper we will report on recent work that we have carried out involving enzymes such as glutamate dehydrogenase (from liver), peroxidase (from horseradish) and tyrosinase (from banana). D3. ADSORPTIVE STRIPPING VOLTAMMETRY OF SOME BIOLOGICALLY IMPORTANT MOLECULES Josino C. Moreira and Arnold G. Fogg, Department of Chemistry, Loughborough University of Technology, Loughborough, Leicestershire L E I 1 3TU, UK Histidine is determined at the 5 x 10-9 M to 1.6 x lop7 M level by differential-pulse adsorptive stripping voltammetry a t a hanging mercury drop electrode using the reduction peak of its copper(l1) complex at -270 mV versus A g - AgCI: free copper(l1) is reduced at - 100 mV. Tryptophan interferes when present at five times the concentration of histidine. The copper(11) complexes of cysteine and cystine adsorb and are reduced a t significantly more negative potentials than the histidine complex. Tyrosine can be determined after coupling with diazotised sulphanilic acid. The adsorptive stripping voltammetry of fluorescein isothiocyanate, phenyl isothiocyanate and their albumin derivatives are described. D4. RADIOTRACER STUDIES OF THE FUNCTIONING OF NEUTRAL CARRIER TYPE ION-SELECTIVE ELECTRODES Natalie K. Harris, G. J. Moody and J. 0. R. Thomas, School of Chemistry and Applied Chemistry, University of Wales College of Cardiff, P.O. Box 912, Cardiff CF1 3T6, UK The use of radiotracers has yielded much useful information concerning the function of ion selective electrode type PVC membranes based o n calcium dialkylphosphates1-3 and metal complexes of nonylphenoxypoly(ethyleneoxy)ethanol.4-6 The studies to be reported here relate t o radiotracer studies with 45Ca, 22Na and 42K for PVC matrix membranes containing a further range of neutral carrier sensors, namely the calcium ionophore (ETH 129 and ETH 1001) and potassium responsive valinomycinbased membranes. The ion permeation data will be discussed in terms of ion-selective electrode response behaviour, particularly with regard to selectivity. Special attention will be given to the effects of the roles of plasticising solvent mediators and anion excluders for further improving the analytical prospects of ion-selective electrodes based on the neutral carrier ionophores. References 1. Craggs, A., Moody, G. J., Thomas, J. D. R., and Willcox, A,, Talanta, 1976, 23, 799. 2. Jaber, A. M. Y., Moody, G. J., Thomas, J. D. R., and Willcox, A., Talanta, 1977, 24, 655. 3. Craggs, A., Doyle, B., Hassan, S. K. A. G., Moody, G. J., and Thomas, J. D. R., Talanta, 1980, 27, 277. 4. Doyle, B., Moody, G. J., and Thomas, J. D. R., Talanta, 1982,29,257. 5. Doyle, B., Moody, G. J., and Thomas, J. D. R., Talanta, 1982,29,609. 6 . Alexander, P. H. V., Birch, B. J., Moody, G. J., and Thomas, J. D. R., Analyst, 1967, 112, 849.

D5. VOLTAMMETRY IN FROZEN ELECTROLYTES T. E. Edmonds and S. K. N. Bath, Department of Chemistry, Loughborough University of Technology, Loughborough, Leicestershire, LEI 1 3TU, UK Voltammetric measurements can be made successfully in an electrolyte provided that there is: a sufficient number of charge carriers t o conduct the current and charge the double layer; a mechanism by which electroactive material can be transported to the electrode surface; and a chemical species present in the system that exhibits electroactive behaviour within the range of accessible potentials. We have investigated the voltammetric behaviour of a number of classic redox couples, such as hexacyanoferrate and orthodianisidine, i n common aqueous electrolytes at or below the freezing-point. Within the temperature range tested all of these electrolytes fulfilled the three criteria mentioned above. Voltam-

metry was performed in these systems using both conventional (glassy carbon) and micro (carbon fibre) electrodes: a threeelectrode cell was employed for all measurements. In this paper we will describe in detail the apparatus for this work and will discuss the implications of the results for the electroanalytical determination of solution species a t high concentrations. D7. AMPLIFIED MASS IMMUNOSORBENT ASSAY WITH A PIEZOELECTRIC QUARTZ CRYSTAL MICROBALANCE Michael 0. Ward and Richard C. Ebersole, Central Research and Development Department, Experimental Station 328, E.I. du Punt de Nemours & Co., Wilmington, DE 19898, USA Amplified mass immunosorbent assays (AMISA) using a quartz crystal microbalance (QCM) are described for the detection of adenosine-5’-phosphosulphate (APS) reductase and human chorionic gonadotropin (hCG). APS reductase detection is accomplished by binding APS reductase t o an anti-APS reductase antibody immobilised o n the surface of the QCM, followed by addition of an anti-APS/alkaline phosphatase reductase conjugate. Subsequent exposure of 5-chloro-4-bromo-3-indolylphosphate (BCIP) to the bound sandwich complex results in enzymatically amplified deposition of the oxidised dimer of BCIP on the QCM surface, resulting in a frequency change that corresponds to the level o f APS analyte. The enzymatic amplification leads t o significant enhancement of the detection limits; levels of about 5 ng m l (10- l4 M) APS reductase can be detected whereas the direct binding of APS reductase at even more elevated concentrations cannot be measured. Assay methodology providing for a re-usable biosensor is also described. In this example, hCG is detected using a horseradish peroxidase conjugate i n which a sandwich complex is immobilised on a separate nylon membrane positioned in close proximity t o a polyvinylferrocene (PV-Fc)film on the QCM. This enzyme catalyses the oxidation of I- t o I+-, which subsequently reacts with the PV-Fc film with concomitant insertion of 13-, resulting in an observable decrease of the QCM frequency. As the formation of PV-Fc+13- can be reversed electrochemically to regenerate the orginal PV-Fc film, this configuration provides for re-use of the detection crysta I. D8. THEORY AND APPLICATION OF ACOUSTIC WAVE SENSORS FOR LIQUID MEDIA Michael Thompson, Department of Chemistry, University of Toronto, 80 St George Street, Toronto, Ontario M5S ?AI , Canada, Ljubinka Rajkovic and Biljana Cavic, Department of Analytical Chemistry, Faculty of Technology and Metallurgy, University of Belgrade, Carnegie Street 4, POB 494, 11001 Belgrade, Yugoslavia The bulk acoustic shear wave (piezoelectric) device has been employed as a sensor for the gas phase for some time. In this mode, the sensor is found t o respond t o added mass and selective signals can be achieved if appropriate films are deposited on the surface of the device. The present paper is concerned with the operation of the device in liquid media. The sensitivity of the sensor to bulk liquid properties, viscosity and density, etc., and to the device liquid - solid interface, will be evaluated. With respect to the latter it will be demonstrated that surface free energy and interfacial viscosity are significant in determining frequency response, in addition t o added mass. The theoretical aspects of acoustic transmission through a perturbed interface will be considered. A9. SEPARATION OF ISOTOPIC AND ENANTIOMERIC COMPOSITIONS BY COMPLEXATION GAS CHROMATOGRAPHY V. Schurig, lnstitut fur Organische Chemie der Universitat, Auf der Morgenstelle 18, D 7400 Tubingen, FRG In complexation gas chromatography an electronically and coordinatively unsaturated transition metal compound is added to the stationary liquid phase. Owing to the fast and reversible chemical interaction between the additive and a solute possessing suitable chemical functionalities for coordination, the separation of structural isomers and isotopomers can be carried out by virtue of chemical selectivity. The separation of optical isomers has also been achieved by employing chiral, non-racemic additives. Thus, chiral ethers, ketones, alcohols, acetals, esters and nitrites, as well as racemates of other classes of compounds, have been quantitatively separated into enantiomers on high-reso\ution capillary columns coated with non-racemic stationary phases such as manganese( II) - or nickel( II)- bis[3-(heptaf~uorobutanoyl)(1R)-camphorate] dissolved in polysiloxanes. As solute derivatisation is generally not required in complexation gas chromato-