2. Ege Analitik Kimya Günleri Özel Sayısı

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J. Ins. Sci. Techn. Balıkesir University, 2000, 2 (2), 2nd_{AACD Special Issue}

EDUCATION OF ANALYTICAL CHEMISTRY

By M.M. KHATER

E-mail: egysac@chem-sci.cairo.eun.eg, Phone: 00 202 5676559 Fax: 00 202 5727556

Education of analytical chemistry as a serving discipline is frequently and effective contributing with other scientific and social sciences in building up scientific knowledge and skill. It has to cope with the increasing importance of analytical chemistry and its role in every aspect of life in the modern society. The role of analytical chemistry and its effect on consumer protection, health, environment and economy is increasing tremendously specially in the new economic system and trade agreements. Education of anal. chem. thus, has to cope with the societal needs and the demands of the labor market both nationally and globally so that we can have well informed, trained and capable specialists that can compete in different industries, laboratories, control units and research groups.

I like to stress on some important points in this domain.

• What is the minimum level of unification of concepts among Anal. Chem. Staff members?

• Do we need to change the curricula and how after? • What do we have to emphasize on in teaching?

• Are there any need to add management, law and cost/ benefit concepts that help anal. chemist to be oriented to problem solving?. • How can quality be assured in anal. chem. education?.

• What are the costs and benefits of incorporating information technology with all its tools to anal. chem. Education?.

• Is education of anal. Chem. limited to university period (under graduates and postgraduates) or it is a long life learning concept? In my talk a comparison between education of anal. chem. in Egypt and the Euro curricula adopted by DAC is given.

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INTEGRATED CALIBRATION METHOD IN ANALYTICAL CHEMISTRY

Paweł Kościelniak

Department of Analytical Chemistry, Jagiellonian University, R. Ingardena 3, 30-060 Kraków, Poland

A concept of the integration of the interpolative and extrapolative calibration methods - commonly used in analytical chemistry - is presented, i.e. it is proposed to perform both methods according to a single calibration procedure. Such an approach allows one to obtain two estimations of the analyte concentration in a sample and to verify it in terms of accuracy. It is suggested to execute the integrated calibration method by the flow injection technique in accordance with two different procedures. The instrumental flow systems designed for this purpose are shown. The principle of both procedural versions is revealed and the specificity of them is discussed. The reasons are explained why the method is worth to be brought into the analytical practice.

Keywords: Analytical calibration; calibration method; flow injection

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FLOW ANALYSIS COUPLED TO INFRAREDSPECTROSCOPY SPECTROSCOPY: A POWERFUL TOOL FOR PROBLEM

SOLVING IN ANALYTICAL CHEMISTRY

Bernhard LENDL

Institute of Analytical Chemistry, Vienna University of Technology, Getreidemarkt 9-151, A-1060 Wien, email: belndl@mail.zserv.tuwien.ac.at

This contribution aims to highlight benefits gained from the combination of flow analysis (FA) with Fourier transform spectroscopy by reporting recent results in the fields of process analysis and time resolved infrared spectroscopy.

In the first example a fully automated FIA-ATR-FTIR system for fermentation control is presented. The process investigated was the Acetone-Butanol-Ethanol (ABE) fermentation which has attracted renewed interest recently as an alternative and environmentally friendly method for the production of solvents. Using an automated flow injection system, problems arising from biofouling of the sensing surface (ATR), pH variation during the fermentation as well as gas formation could be solved making the continuous monitoring of 5 target analytes during complete feed batch fermentations possible.

In the second example a universal approach for fast time resolved MIR spectroscopy of arbitrary chemical reactions in solution based on a specially developed multi-sheath flow mixer is presented. The micro-machined mixer is made of polymers and produced on top of IR transparent CaF2 windows. The developed mixer produces out of two macroscopic streamlines an alternating sequence of micro-streamlines (width below 20 µm). Due to the short residence time (below 5 ms) of the stream lines in the flow cell and due to the fact that strongly laminar conditions prevail hardly any mixing occurs as long as the flow is maintained. However, upon stopping the flow rapid diffusion based mixing occurs which allows to initiate any chemical reaction of interest and to follow the reaction dynamics on a molecular basis. In this presentation the principles of the new technique will be outlined as well as first data on selected chemical reactions shown.

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METHODS OF SAMPLE THERMAL MODIFICATION BY MEANS DOUBLE VAPORIZATION IN TWO STEP ATOMIZER FOR

ATOMIC ABSORPTION ANALYSIS.

Ilia Grinshtein, Yuri Vilpan, Alexei Saraev and Lubov Vasilieva

Russian Research Center “Applied Chemistry”, 14, Dobrolubova Ave., St-Petersburg, 197198, Russia

Fax: 7-812-2381162, telephone: 7-812-3254008, e-mail: grin@an.apchem.spb.ru

After sample vaporization in two-step atomizer with a purged vaporizer sample vapors can be transferred into preheated or into non-heated atomizer. In the last case the atomizer walls trap the vapors and then the sample is second time vaporized and atomized by heating the atomizer. Thermal pre-treatment of a sample using this double vaporization makes possible the direct analysis of samples with strongly interfering matrices including solids. The technique was used for the direct determination of Cd and Pb in human urine, high concentrated water solutions of NaCl, Na2SO4, NaNO3, KH2PO4 and NH4H2PO4 matrices, potatoes, wheat, bovine liver, milk powder, grass-cereals mixture, caprolactam, bituminous-shale and polyvinyl chloride plastic without chemical modification or any other sample pre-treatment.

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OLIVE OIL ANALYSIS BY FLOW INJECTION

Constantinos A. Georgiou

URL: http://www.aua.gr/georgiou E-mail: cag@aua.gr Phone: +301-5294248 Fax: +301-5294265

Agricultural University of Athens, 75 Iera odos, Athens 118 55, Greece

Flow Injection (FI) automated methods for the quality assessment of olive oil will be presented. The methods are based on laboratory made analysers, providing automated data acquisition and control. Reagents are continuously pumped by a peristaltic pump through PTFE micro-tubes of 0.8 mm inner diameter (coils). Micro-quantities of olive oil are automatically injected in the flow using a chromatography injection valve. Samples are mixed with the reagents and incubated while flowing to the spectrophotometer. For methods based on slow reactions, a Parallel Flow

Injection (PA-FI) multichanell analyser based on a stream selection valve

and ten incubation coils, was developed. While stored samples are incubated, new samples are injected and mixed with the reagents. Then, incubated samples are aspirated in the spectrophotometer by flow reversal. After measurement, samples are driven to waste. The PA-FI analyser allows automation of methods that require long incubation times without loss of sampling rate, overcoming the ‘one sample at a time’ disadvantage of FI. The developed automated methods provide determination of the following parameters:

•

Acidity Peroxide value Iodine value

Thiobarbituric acid reactive substances and Anisidine value

Advantages of the developed flow injection methods are:

High analysis rates: 20-100 samples per hour

Full automation: Sampling, weighting, sample pretreatment, analysis

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button. Lack of human intervention results in increased precision and accuracy

•

Low cost: 0.2-7 ml of organic solvents are consumed per analysis. The

low solvent consumption and the replacement of chlorinated solvents renders the developed methods environmental friendly

Low sample consumption: 0.0012-0.2 ml per analysis Good agreement with time consuming official methods Protection of reagents from light and atmospheric oxygen

Parallel Flow Injection multichanell analyzer for Olive Oil Peroxide Value determination.

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DESIGN AND APPLICATIONS OF CHEMFETS BASED ON BULK

CATION-EXCHANGE MEMBRANES

N. A. Chaniotakis, E. A. Moschou

Laboratory of Analytical Chemistry, University of Crete Iraklion 71 409 Crete GREECE

Tel# +30 81 393 618 FAX# +30 81 393 601 e-mail: nchan@chemistry.uch.gr

The use of a new type of ion selective membranes with the ability for bulk ion partitioning, in conjunction with ion selective field-effect transistors (ISFETs) allows for the development of electrochemical microsensors (CHEMFETs) based on an original response mechanism. The ion-partitioning membrane incorporates two different ionophores, one selective to protons and the other to analyte cations, as well as the necessary anionic lipophilic sites. As dictated by the electroneutrality principle, when the concentration of the analyte cations in the sample increases (for example potassium), K+_{is extracted into the membrane phase displacing protons of} equal charge out of the membrane. The pH-sensitive gate of an ISFET or the surface of a glass pH electrode is used as an internal transducer for the monitoring of the membrane proton flux. The resulting signal of the pH transducer is related to the concentration of the analyte cation present in the sample. The results presented in this lecture will show the analytical characteristics of this new type of sensors for single and doubly charged cations, as well as possible applications in environmental and clinical chemical analysis.

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RECENT DEVELOPMENTS IN THE DETERMINATION OF HYDROGEN PEROXIDE AND PERACIDS USING CCD TECHNOLOGIES, NEW REAGENTS AND DERIVATIZATION

TECHNIQUES

M.I. Karayannis, A.C. Pappas and C.D. Stalikas

University of Ioannina, Laboratory of Analytical Chemistry, 45110 Ioannina, GREECE,

Tel: xx30-651-98406, Fax: xx30-651-98407, e-mail: mkaragia@cc.uoi.gr Hydrogen peroxide and peroxycarboxylic acids have been identified to be ecologically beneficial reagents for disinfection and bleaching purposes [1]. Due to the considerable increase of peroxide consumption in industrial processes, the development of selective and accurate analytical methods has stimulated research in this field [2].

A method is described here based on the separation of hydrogen peroxide and peracids on a reverse-phase HPLC system following post-column reaction with a concentrated solution of potassium iodide.

The reaction of peroxides with acidified KI in the presence of ammonium molybdate as catalyst was used:

H2O2+ 2I-+2H+ I2+2H2O

I2+ I- I

3-The measurement of I3- by its optical absorption forms the basis of the triiodide method. The high molar absorptivity of I3¯ (26500 M-1·cm-1) and fast reaction rate makes the I3¯method convenient for the determination of both hydrogen peroxide and peracids. A series of standard solutions containing H2O2, PAA (peroxyacetic acid) and mCPBA (3-chloroperbenzoic acid) were injected through a 20 µl injection loop. Detection was performed at 352 nm. Under the optimal HPLC conditions good separation was attained.

The method was applied to monitor the formation of PAA in the course of a washing cycle performed with a laundry detergent marketed under the trade name ‘Persil’. The method was compared with that using direct UV detection of the studied compounds. The proposed method

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features improved analytical characteristics with most salient the low detection limit at 10-6_{M levels.}

Recently our group has synthesized 4-aminopyrazolone derivatives as chromogenic agents for the spectrophotometric determination of phenols [3]. These simple and long conjugated chromophores were used as substitutes for 4-aminoantipyrine in Trinder reaction [4].

The reaction of such chromophores (4-amino-5-(p-aminophenyl)-1-methyl-2-phenylpyrazol-3-one (DAP) with water-soluble hydrogen donors i.e. N-ethyl-N-sulphopropylaniline sodium salt (ALPS) [5] in the presence of peroxidase has been utilized to develop a new, simple and fast method for the determination of hydrogen peroxide at nanomolar levels.

The coloured product formed is monitored spectrophometrically using a 50 cm optical fiber liquid waveguide capillary cell and a CCD (Charge Coupled Device) detector.

REFERENCES

[1] Wurster P., Text. Prax. Int., 47(10), 960-965, (1992) [2] Effkemann S., et al, Anal. Chem., 70, 3857-3862, (1998) [3] Y.C.Fiamegos, C.D.Stalikas, G.A.Pilidis and M.I.Karayannis,

Anal.Chim.Acta, 403(2000) 315-323 [4] Barham D., Trinder P., Analyst, 1972, 97, 142-145

[5] Katsumi Tamaoku, Yuko Murao and Kayoko Akiura, Anal. Chim. Acta 136(1982) 121-127

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THE IMPORTANCE OF CHEMICALLY MODIFIED ELECTRODES IN VOLTAMMETRY AND FLOW SYSTEM

Gürel Nişli, Zekerya Dursun

Ege University, Science Faculty, Department of Chemistry 35100 Bornova, İzmir, Turkey

Chemically modified electrodes(CMEs) have had a dominant position in many electrochemical studies since the 1970's. These electrodes are made by incorporating chemical groups on the bare electrode surface which are suitable for the analytical purpose. These procedures offer increased sensitivity and selectivity or decreased operational potential required to oxidized or reduced electroactive species, enrichment of metal ions and determination of non-electroactive compounds using ion-exchange properties. CMEs modification procedures are based on; (1) direct adsoption of modifier on to the bare electrode surface, (2) covalent bonding of the modifier to a specific surface site, (3) physical coating of the electrodse surface with a polymer and (4) mixing the slightly soluble modifier with a conductive.matrix,,such,,as,,carbon,,

paste.

Adsorption is the oldest procedure used for electrode modification. In this method, the electrode is simply soaked for a period of time in a solution of the modifier substance then washed with pure water. The self-assemble of mono layers(SAMs) of adsorption types of modification have been actively studied in recent years. SAMs of alkenthiols or aromaticthiols on single crystal metal surfaces such as gold, silver and nickel have been extensively studied for both scientific reasons and possible technolocigal applications for example, lubrication, adhesion, corrosion inhibition and microelectronic fabrications and eelectrochemical sensors or for modifying the cataliytic properties of electrodes. The second method; bare electrode surface are coated with linking agents such as organosilanes or cyanuric chloride which are used to covalently attach from one to several monomolecular layers of the chemical modifier to the electrode surfaces. Polymer film coated CMEs can be prepared by using dipcoating and droplet solvent evaporation, oxidation or reduction deposition, electropolymerization, cross-linking, and radiofrequency polymerization. The fourth method, CMEs can be prepared in a few minutes by simply hand

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mixing required portions of modifier, graphite powder and organic binder. This mixture can be packed into an electrode body and smoothed to give the

new surface by extrusion and repolishing to give the same reproducibilty as ordinary carbon paste.CMEs once optimized; can also be used in electrochemical detectors for the effective monitoring of flowing stream or hydrodynamic processes, such as Liquid chromatograpy(LC-EC) or amperometric detection with flow injection analysis(FIA). For analytical applications, CMEs should possess certain properties; good mechanical and chemical stability of electrode surface, good short-term reproducibility and long-term stability of the modifiers activity towards the analyte, wide dynamic range of responds, low and stable background currents over the potential range reguired, simple and reliable fabrication that results in consistency of the response from one electrode..to..another.

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ORGANIC TRACE ANALYSIS UNDER GLOBAL ASPECTS - THE GLOBE AS A REACTION FLASK

K. Ballschmiter

Department of Analytical and Environmental Chemistry University of Ulm D-89069 Ulm Germany Email: karlheinz.ballschmiter@chemie.uni-ulm.de

Organic trace analysis in environmental science mostly deals with multi-matrix and multi-component problems. In environmental science concentrations of the looked-for components are often in the microgram/Kilogram (ppb) range or may be even go down to the nanogram/Kilogram (ppt) range. Examples in organic trace analysis combining such extremes are the determinations of polyaromatic hydrocarbons (PAH), polychlorinated naphthalenes (PCN, ClxN, x=1-8, 75 congeners), polychlorinated biphenyls (PCB, ClxB, x=1-10, 209 congeners), polychlorinated dibenzo-p-dioxins (PCDD, ClxDD, x=1-8, 75 congeners) and polychlorinated dibenzofurans (PCDF, ClxDF, x=1-8, 135 congeners) among others in a variety of sample types. A special task is the determination of the 96 tetrachlorobenzyltoluene (TCBT) isomers in the technical mixture Ugilec.

The lecture will focus on the question, where do such persistent anthropogenic organic pollutants (POPs) go when they apparently disappear in the global environment. It summarizes approaches and results of our studies of the general baseline pollution. These studies combine extreme organic trace analysis and global environmental chemistry.

Any analytical procedure is a chain of operations that can be summarized as follows: definition of the problem, definition of the general analytical approach, definition of the sample in terms of significance under temporal and spatial aspects, sampling, sample transportation and storage, aliquoting of sample, depletion of the matrix compounds (often summarized as sample preparation), separation and detection of the analytes,

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identification and quantitation, calibration and validation of the results and finally discussion of the obtained results under the aspect of the starting problem.

While the steps "separation" and "detection" are widely considered as an exciting part of science in analytical chemistry if not the only topic at all, the fields "sampling" and "sample preparation" are often left to the motivated technical assistant or so called standard procedures are applied. The chain picture given above names it, any chain is as weak as its weakest link. Poor sampling and/or poor sample pre-treatment makes poor analytical chemistry if one considers accurate results as an important part of the scientific effort.

Sampling in global environmental chemistry requires the consideration of pre-sampling factors (where, what, when, transport, energy supply) as well as an optimizing of the real sampling parameters of time and space. Sampling is the problem oriented cutting out of a selected but representative piece of our environment regarding the factors time and space. Sampling transforms the idea of a scientific problem to a piece of physical reality.

Sample preparation is enrichment of the analytes from the total sample minimizing interfering organics and avoiding any significant losses of the analytes A nanogram per kilogram level of the analyte in the sample has to be transferred into a nanogram per 25 microlitre level in an organic solvent ready for further separation and detection steps. This is an enrichment by the factor of 105. The steps extraction/dissolution, removal of interfering matrix components (clean-up), and preseparation by liquid chromatography into groups of related compounds are crucial for reducing the number of organic components to a level which is amenable to separation by high resolution gas chromatography.

During the last decade organic trace analysis has triggered and also has been driven by a development of so called instrumental techniques. The use of a mass-spectrometer as a detection device particularly in true combination with high resolution separation techniques in the gaseous or the liquid phase - GC/MS; LC/MS, CE/MS - has a still lasting impact. HRGC/MS operation give three basic types of analytical information: firstly retention time as a measure of the molecular interaction of the analyte with the stationary phase in the GC part, secondly data regarding the molecular

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structure as given by the ion pattern, and thirdly a signal that correlates to the amount of the analyte entering the ion source.

Sensitivity in HRGC-MS, besides requiring an optimized functioning of the ion source and the ion separation part, depends primarily on the structural parameters of the analytes. Strong molecular ions or fragments such as they are obtained with many arene compounds clearly give optimum sensitivity. Even with an electron-impact source 0.1 - 1 pg of an arene can be detected in the multiple-ion mode of a sector field instrument. Negative ion chemical ionisation has detection limits well into the femtogram range, if one uses the right compounds.

Quantitation by GC-MS particularly when a multiplicity of analytes has to be determined should always operate on the basis of keeping all operational parameters constant. Only this way the given inherent systematic errors can be regarded as similar in both the calibration and the analytical runs. 13C-isotope labelled analyte identical compounds give an optimum in error compensation right on from the beginning of the analytical process. 13C-isotope dilution analysis (IDA) is typical for the determination of a single or at utmost a few analytes. For the analysis of more than ten and up to 50 or more analytes in a complex mixture the extend and the specifity of the synthetic procedures alone to obtain the necessary 13C-standards is mostly self-prohibiting.

It has been shown by us that the MSD after electron impact ionization (EI-MS) gives a rather strict molar proportionality for the polychlorinated arenes, like the naphthalines, dibenzodioxins and dibenzofurans. For the PAHs and the polychlorinated naphthalenes the normalized signal of the isotope pattern has to be corrected by the ionisation cross-section to obtain a molar proportionality. In contrast to these groups of compounds the relative EI-MS response factors of the PCBs isomers differ quite substantially.

The mass spectrometer detector is an extremely helpful positive identification device in analytical chemistry, whereas most other detectors merely detect an analogy between an unknown and a reference standard. But one should always bear in mind when using a specific detector such as a mass spectrometer that it only answers the questions being asked for.

References (covering the topics of the abstract) K. Ballschmiter:

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"Transport and Fate of Organic Compounds in the Global Environment" Angew. Chem. Int. Ed. Engl. 31(5) (1992) 487-515.

J. Ehmann, K. Ballschmiter:

"Isomer-specific determination of tetrachlorobenzyltoluenes (TCBT) in the technical mixture Ugilec 141 by capillary gas chromatography" Fresenius Z Anal Chem 332 (1989) 904-911

R. Fischer, K. Ballschmiter:

"Congener-specific identification of technical PCB mixtures by capillary gas chromatography on a n-octyl-methyl silicone phase (SB-Octyl 50) with electron capture- and mass-selective detection" Fresenius Z. Anal. Chem. 335 (1989) 457-463

R. Bacher, M. Swerev, K. Ballschmiter:

"Profile and Pattern of Monochloro- through Octachlorodibenzodioxins and -dibenzofurans in Chimney Deposits from Wood Burning" Environ. Sci. Technol. 26 (1992) 1649-1655.

K. Ballschmiter, A. Mennel, J. Buyten:

"Long chain alkyl-polysiloxanes as non-polar stationary phases in capillary gas chromatography" Fresenius J. Anal. Chem. 346 (1993) 396-402. J. Kurz, K. Ballschmiter:

"Isomer-specific determination of 79 polychlorinated diphenyl ethers (PCDE) in cod liver oils, chlorophenols and in a fly ash" Fresenius J. Anal. Chem. 351 (1995) 98-109.

T. Wiedmann, U. Riehle, J. Kurz, K. Ballschmiter:

"HRGC-MS of polychlorinated phenanthrenes (PCPhen), dibenzothiophenes (PCDT), dibenzothianthrenes (PCTA), and phenoxathiins (PCPT)"

Fresenius J. Anal. Chem. 359 (1997) 176-188.

J. Krupcik, A. Kocan, J. Petrik, P.A. Leclercq, K. Ballschmiter: "On the Use of Reference Standards for Quantitative Trace Analysis of PCBs by HRGC. Analyses of Technical PCB Formulations by HRGC/FID" Chromatographia 33 (1992) 514-520.

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"Molar Response of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans by the Mass Spectrometric Detector" Anal. Chem. 65 (1993) 640-644.

T. Wiedmann, H. Schimmel, K. Ballschmiter:

"Ion Trap MS/MS of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans: Confirming the Concept of the Molar Response" Fresenius J. Anal. Chem. 360 (1998) 117-119.

K. Ballschmiter, R. Wittlinger:

"Interhemisphere Exchange of Hexachlorocyclohexanes,

Hexachlorobenzene, Polychlorobiphenyls, and 1,1,1-Trichloro-2,2-bis(p-chlorophenyl)ethane in the Lower Troposphere" Environ. Sci. Technol. 25 (1991) 1103-1111

J. Schreitmüller, K. Ballschmiter:

“The Equilibrium Distribution of Semivolatile Organochloro Compounds between Atmosphere and Surface Water in the Atlantic Ocean“ Angew. Chem. Int. Ed. Engl. 33 (1994) 646-649

T.O. Wiedmann, B. Güthner, T.J. Class, K. Ballschmiter: "Global Distribution of Tetrachloroethene in the Troposphere: Measurements and Modeling"

Environ. Sci. Technol. 28 (1994) 2321-2329. U. Führer, K. Ballschmiter:

"Bromochloromethoxybenzenes in the Marine Troposphere of the Atlantic Ocean: A Group of Organohalogens with Mixed Biogenic and Anthropogenic Origin"

Environ. Sci. Technol. 32 (1998) 2208-2215 R. Fischer, J. Kastler, K. Ballschmiter:

"Levels and pattern of alkyl nitrates, multifunctional alkyl nitrates, and halocarbons in the air over the Atlantic Ocean" J. Geophys. Res. (2000) 14473-14494.

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NOVEL TRAPS IN VAPOUR GENERATION ATOMIC SPECTROMETRY

O. Yavuz Ataman

Department of Chemistry, Faculty of Arts and Sciences, Middle East Technical University, 06531 Ankara, Turkey

Vapour generation is one of the most common ways of sample introduction into flame, plasma, heated quartz tube or even electrothermal atomizers for AAS, ICP-OES and ICP-MS. In the last decade, the same idea is used for electrothermal vaporizer (ETV) devices. Separation of analyte in form of atomic vapour in case of Hg, and in the form of hydride gas for a number of elements has advantages, such as elimination of the matrix and thus providing a simpler, less loaded environment in the atomization and measurement zone. A detailed study for hydride generation can be found in the monograph by Tsalev and Dedina [1].

We have been working on atom traps, mainly concentrating on slotted quartz tubes [2-4]. This on-line preconcentration technique allows one to obtain ng/mL detection limts for some volatile elements, such as Cd, Pb, Zn, In.

Cold vapour AAS method has been applied for Cd determination [5,6]. A novel on-line trap has been developed by our group for CVAAS determination of Cd. In this work, we had an attempt to improve sensitivity by using a Pt trap between the gas/liquid separator and the quartz tube. The Pt trap temperature was controlled electrically where it is employed as a resistor. The Cd was collected at room temperature. After collection period, the Pt wire is resistively heated to hot red temperatures to release the pre-collected analyte which is then pushed to quartz tube for determination. The analytical parameters were, the concentrations of HCl and NaBH4, flow rate of Ar, flow rates of HCl and NaBH4 solutions, collection and releasing temperatures for analyte. Using a 2 mL sample loop and flow injection technique, detection limit (3s) was 3.7 ng/L .

Another novel trap under development is a quartz chamber placed between the atomizer and the vapour generation device. Pb can be trapped at around 300 °C, followed by atomization using a H2/O2 flame. The technique

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can be applied to some other hydride forming elements as well as Cd and possibly Hg.

References

[1] J. Dedina, D.L. Tsalev, “Hydride Generation Atomic Absorption Spectrometry”, Wiley, Chichester, 1995.

[2] Ş. Süzer, N. Ertaş, S. Kumser, O. Y. Ataman, Applied Spectroscopy, 51, 1537-1539, 1997.

[3] Ş.Süzer, N. Ertaş, O. Y. Ataman, Applied Spectroscopy, 53, 479-482 ,1999. [4] O. Yavuz Ataman, “Atom Traps in Flame Atomic Absorption

Spectrometry”, 1st Aegean Analytical Chemistry Days, İzmir, Turkey, 18-20 November 1998.

[5] X.- W. Guo, X. –M. Guo, Anal. Chim. Acta, 310, 377 (1995). [6] X.- W. Guo, X. –M. Guo, J. Anal. At. Spectrom., 10, 987 (1995).

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INTERACTIONS OF XENOBIOTICS AND NOM IN WATER

Fritz. H. Frimmel, Gerd Ohlenbusch, Michael Kumke

Universität Karlsruhe, Institut, Wasserchemie, Engler-Bunte-Ring 1,

76131 Karlsruhe, email: fritz.frimmel@ciw.uni-karlsruhe.de

Natural organic matter (NOM) is present in surface, pore and ground waters. In all these areas interactions of xenobiotics with NOM can be observed. The interactions can be divided in two different groups: a partitioning process of hydrophobic substances and a more specific binding of substances with functional groups. It is well known that these interactions influence the fate and transport of xenobiotics. For example changes in solubility, bioavailability and toxicity have been determined for several xenobiotics. The measurement of these interactions, especially the sorption to dissolved organic matter (DOM), is still an analytical challenge. There are various methods described in literature. However, most of them are prone to disturbe the sorption equilibrium during the measurement and hence, the sorption coefficients obtained have to be considered with care. Two methods that have no separation step and are therefore less prone to this interference are the fluorescence quenching technique and the solid phase micro extraction (SPME). The fluorescence quenching technique is based on the effect, that the analyt loses his fluorescence activity after sorbing to NOM. After recording the steady state fluorescence spectra at different NOM concentrations the fluorescence intensities were evaluated according to the Stern-Volmer equation.

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)

(

1

0

DOC

K

I

SV F F

₌

₊

_⋅

_β

Here IF represents the corrected fluorescence intensity in the absence (0) and presence of NOM (in mg/L DOC) and KSV the binding constant (in L/mg). The fluorescence quenching method is limited to fluorescing compounds and due to the inner-filter correction to a NOM concentration below 35 mg/L DOC.

A promising technique that is applicable for a broad variety of compounds is the SPME. Due to the small amount of analytes extracted it is reasonable to assume that the disturbance of the equilibrium is negligible. Moreover, in case of independent sorption processes this method makes it possible to determine the sorption constants of a mixture of xenobiotics simultaneously.

In our approach we compared the results of both methods for the same xenobiotic/NOM systems to get more information about the quality and limitations of the two methods and of the sorption process itself. The results showed that the sorption constants determined by the fluorescence quenching method (KSV) were 3 to 13 times higher than the sorption constants determined by SPME (KDOC). This difference can be explained by different interaction processes. Therefore we proposed inner and outer

sphere interactions. In the fluorescence quenching approach all analyte

molecules, even the ones weakly attached to the outer sphere of NOM, were quenched and hence detected as ‘bound’. In the SPME approach, on the other hand, the analytes weakly attached to the outer sphere of NOM could readily exchange with the aqueous phase and are extractable by the SPME fiber. As a result they were not detected as ‘bound’. This theory corresponds with fluorescence line narrowing spectroscopy experiments at low temperature that showed that in presence of humic acid a change of the site distribution and relative intensities of the ground state vibrations in the

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fluorescence spectrum of pyrene has occurred, which can be related to an altered microenvironment of pyrene in the presence of humic acid.

This different results of the two methods indicate that the choice of the analytical method is dependent on the aim of the measurement. For photochemical research KSV might be more useful whereas for the estimation of transport and bioavailability the constants determined by SPME are of higher relevance.

Further measurements showed that the sorption constants increase with decreasing pH. In case of hydrophobic xenobiotics without functional groups this can be explained by the increased hydrophobicity of the

protonated NOM. In case of xenobiotics with protonated functional groups, like phenols, the reduced solubility and reduced hydrogen-bond interactions with water are also responsible for a better sorption.

To investigate the soprtion of phenols to DOM further measurements with the SPME were performed with a set of various phenols. The phenols showed a negligible sorption to natural DOM and a small sorption with log KDOC-values between 2 and 3 to the commercial humic acid Aldrich-HA. A much stronger binding was observed to the protein bovine serum albumin (BSA) with log KDOC-values between 2 and 6. The determined sorption constants showed a good correlation with the octanol/water partitioning coefficient (log KOW). A further correlation was performed with the linear solvation energy relationship model (LSER). These model, developed by Kamlet and coworkers, based on the assumption that chemical properties depend on solute-solvent interactions. It can be described by the following equation:

log K_DOC = ⋅m V_X + ⋅r R₂+ ⋅s _π_H2 + ⋅a

∑

_α2_H + ⋅b

∑

_β_H2 +c

The single terms of the equation that contain a constant (m, r, s, etc.) and a solvation parameter (Vx, R2, etc.) describe specific interactions between the phenols and DOM. The cavity term (m ⋅ Vx) is a measure for the difference between water and DOM in forming a cavity for the phenol. The

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α₂H

s⋅π_H2

•

influence of hydrogen-bonds on the sorption is described by the terms (a ⋅ ) and (b ⋅ ). The values of the solvation parameters needed for the correlation were taken from literature and the constants were calculated by multiple linear regression.

∑

_∑

β₂H

The results showed that the difference in cohesion between water and DOM is the main driving force for the sorption of the phenols. This is indicated by a positive value of m. The water has a strong tendency to form its preferred liquid structure and therefore in comparison to DOM it is harder to form a cavity for the phenol. As a result the phenols were expelled out of the water phase and adsorb to the DOM. The contributions of lone-pair electron interactions (r ⋅ R2) and dipole-dipole interactions ( ) are relatively small. The sorption of phenols is reduced by hydrogen-bond interactions (negative a and b). The type of hydrogen-bond interactions, where the phenols act with the strong hydrogen-bond acid water as a hydrogen-bond base, are mainly responsible for the reduction of the sorption and strongly determine the values of the sorption constants. The hydrogen bond-basicity of the phenols increases with increasing pKa-values. As a result the hydrogen-bonds with water molecules become stronger and the sorption to DOM is decreasing.

The regression coefficients of R = 0,950 and R = 0,911 for Aldrich-HA and BSA show a good correlation between the sorption constants and the solvation parameters. As a consequence, the LSER model allows an estimation of sorption constants of different phenols.

Literature

Kumke, M. U.; Löhmannsröben, H.-G.; Roch, T.: Fluorescence quenching of polycyclic aromatic compounds by humic acid. Analyst 119, 997-1002, 1994

Doll, T. E.; Frimmel, F. H.; Kumke, M. U.; Ohlenbusch, G.: Interaction between natural organic matter (NOM) and polycyclic aromatic

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•

compounds (PAC) – comparison of fluorescence quenching and solid phase micro extraction (SPME). Fresenius J. Anal. Chem. 364, 313— 319, 1999

Kumke, M. U.; Frimmel, F. H.; Ariese, F.; Gooijer, C.: Fluorescence of humic acids (HA) and Pyrene-HA complexes at ultralow temperature. Environ. Sci. Technol. 34, 3818-3823, 2000

Ohlenbusch, G.; Kumke, M. U.; Frimmel, F. H.: Sorption of phenols to dissolved organic matter investigated by solid phase microextraction. Sci. Tot. Environ. 253, 63-74, 2000

Ohlenbusch, G.; Frimmel, F. H.: Investigations on the sorption of phenols to dissolved organic matter by QSAR studies. Chemosphere (in press)

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THE DETERMINATION OF BACKGROUND LEVELS OF VOLATILEORGANIC COMPOUNDS IN THE ATMOSPHERE

M. Veber, M. Pompe, H. Baša

Faculty of Chemistry and Chemical Technology, University of Ljubljana, Askerceva 5, 1000 Ljubljana, Slovenia

E-mail:marjan.veber@uni-lj.si

Volatile organic compounds (VOCs) of anthropogenic as well as biogenic origin play an important role in different photochemical processes in the troposphere. In order to evaluate their impact on ozone formation processes, a detailed knowledge about their abundance in the atmosphere is required. There are several different analytical methods available for the determination of background levels if VOC in the air. Sampling can be performed either collecting the whole sample (e.g. canister, bags) or by preconcentration on absorption tubes or cold traps. For their determination gas chromatography using different detectors (FID, ECD, MSD) is applied.

The absorption tubes filled with different adsorption materials (i.e.Tenax, Carbotrap, Carbosieve,) to collect VOC from C2 to C10 were applied and the absorption efficiency of individual absorbents was tested. Special attention was dedicated to the sampling of biogenic compounds.

The samples were cryo-refocused after thermal desorption and injected on gas-chromatographic capillary column. Two separation methods were developed. The first one includes separation of C2 to C10 isomers using nonpolar OV-1 column. Baseline separation of C2 isomers was obtained by cooling the chromatographic oven to -60o_{C. To avoid multiple overlapping} of chromatographic peaks two-column system was developed. While Al2O3/KCl PLOT column was used for the separation of high volatile VOCs (C2 to C6) lower volatile VOC were separated using nonpolar DB-5MS column. The identification of VOC was performed using several standards and MS detector, while quantitative results were obtained with FID detector.

Since unspecific fragmentations in the homologous series can hinder identification of the unknown substances during gas chromatographic separation coupled with mass spectrometry, some chemometric approaches have been introduced to solve this problem.

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The accuracy of the developed methods was performed by comparison of results obtained by different laboratories during field measurements.

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NEW TRENDS IN ELECTROANALYSIS USING BIOSENSORS

Anastasios Voulgaropoulos

Laboratory of Analytical Chemistry, Chemistry Department, Aristotle University of Thessaloniki,

56004 Thessaloniki, Greece

e-mail: voulgaro@chem.auth.gr

Biosensors based on electrochemical detection are of great interest in the recent years due to their low cost and high selectivity.

They are applied in clinical chemistry and biochemistry, however, they also show great promise in environmental monitoring, agro-industries and biotechnologies.

Mainly they are using enzyme electrodes, but also DNA-modified electrodes are very much promising tools.

Enzyme electrodes are obtained by combination of an electrode surface, generally platinum, gold, silica, graphite or glassy carbon, with an enzyme, most frequently an oxidase or dehydrogonase, which is either immobilized covalently on the electrode surface, or cross-linked within a polymer or redox polymer network, or encapsulated within a silica matrix, simply mixed with carbon paste, or physically retained by means of a dialysis membrane.

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DETERMINATION OF THALLIUM IN SOME GEOLOGICAL AND METALLIC SAMPLES BY ELECTROTHERMAL ATOMIC

ABSORPTION SPECTROMETRY

Trajce Stafilov1*_{and Dragan Mihajlovic}2

1_{Institute of Chemistry, Faculty of Sciences, St Cyril and Methodius}

University,

P.O. Box 162, 91001 Skopje, Macedonia

2_{RZ Tehnicka kontrola AD, 91000 Skopje, Macedonia}

Thallium is a rare element, present in the earth crust below 1 ppm. During the weathering processes it is accumulated in sediments and soils where, furthermore, its content is increased as a result of human activity.

Besides the low abundance of thallium and its limited application, analysis of this element is important task due to the toxicity of thallium compounds. On the territory of the Republic of Macedonia there are several thallium contamination sources: zinc and lead mines “Sasa” and “Toranica”, zinc and lead metallurgical plant “Zletoyo”, ferromanganese metalurgical plant “RZ Topilnica”, coal burning power plant”REK Bitola” and cement factory “Usje”. A particularly geochemical, physical and analytical interest has a polymetallic sulfide deposit in region known, as Allchar, on Mount Kozuf in R. Macedonia, rich with thallium minerals.

From these reasons, a method for thallium determination in geological and soil samples by electrothermal atomic absorption (ETAAS) was developed. Different procedures for sample decomposition have been examined for obtaining reliable results. Several ammonium salts as chemical modifiers have also been applied for stabilization of thallium species in graphite atomizer. The limit of thallium determination by this method was 0,1 µg/g Tl.

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ON-LINE-SAMPLE PREPARATION TECHNIQUES (SPE) COUPLED TO HPLC-UV AND MS-DETECTION FOR THE

ANALYSIS OF ORGANIC MICROPOLLUTANTS

E. Rosenberg

Institute of Analytical Chemistry, Vienna University of Technology, Getreidemarkt 9/151

A-1060 Vienna, Austria. Phone: +43-1-58801/15190. Email: erosen@mail.zserv.tuwien.ac.at

Organic micropollutants are a potential threat for water resources all over Europe and require thus continuous monitoring. For this reason, more than 130 micropollutants have been listed in the Directive 76/464/EEC of the European Community which contains mostly organic and organometallic species. Standard methods for the determination of these compounds are gas and liquid chromatography, mostly accompanied by complicated and tedious sample preparation schemes.

For phenols which shall be chosen here as model analytes and are important and practically ubiquitous industrial pollutants, the primary method of analysis is liquid chromatography. Liquid chromatography is preferred in this case to gas chromatography since their reactivity makes them difficult to be quantitatively determined by GC. Furthermore, GC does not lend itself easily to the automation and integration of the entire analytical procedure.

The approach presented here is the on-line coupling of solid phase extraction (SPE) with liquid chromatography and parallel UV and mass spectrometric detection (HPLC-UV/MS). Liquid chromatography is capable of separating all of the relevant phenols listed in the US EPA priority list and can be ideally combined with on-line sample preparation by solid phase extraction. Yet, this combination requires careful optimisation to achieve maximum sensitivity, both from the sample preconcentration and the separation/detection side, particularly when mass spectrometric detection is used.

The optimisation of the sample enrichment includes the determination of the best suited SPE material and the optimisation of the SPE conditions. The optimisation of the separation and detection should be undertaken jointly: Here, it is often recognised that conditions which are

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optimal for the separation of the investigated phenols are not for their detection: Usually good chromatographic separation of the entire range of phenols requires the addition of mobile phase modifiers, e.g. acids or buffers. The addition of mobile phase modifiers however is usually strongly decreasing the MS response for the phenols under study. Therefore, compromise conditions have to be found for achieving good chromatographic separation and sensitivity.

The optimisation of the entire analytical method, its validation and the application of the developed method to waste water samples will be presented. It offers excellent sensitivity for the detection of the range of EPA phenols (in the low ng/L-range in favourable cases), minimises the manual intervention for sample preparation and time required per analysis due to fully automated operation.

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FURNACE-FLAME ATOMIZER AND ITS ABILITY AT THE ATOMIC ABSORPTION ANALYSIS SOME OF ENVIRONMENTAL

A.N.Zacharia, A.N.Chebotarev, Z.S.Krasnyanskaya, M.A.Gotvyanskaya

Department of Analytical Chemistry I.I.Mechnikov Odessa State University 65014, Ukraine, Odessa, Marazlievskaya str., 1A/8. tel.(0482)25-39-76;

e-mail: zacharia@chemt.intes.odessa.ua

The atomic absorption spectroscopy (AAS) is one of the most effective analytical chemistry methods that widely used in environmental investigations. Thus the sensitivity its flame variant is insufficient for determination some of chemical elements in the corresponding materials. The utilized for solution this problem electrothermal (ET) AAS in the most cases are accompanied with different sort of interference effects which are satisfactory classified on the whole. For their elimination or reduced in analytical practice AAS different modes and receptions are proposed: separation of elements to be determined from the base components of analyte, matrix modifiers, L’vov platform, STPF-technique, Zeeman effect, improving of constructions (heightening isothermal) graphite furnace etc.

As is known that so-called electrothermal atomizers the opened type, including combined with high-temperature flame: furnace-flame, capsule-flame, Delves cup and similar are characterized satisfactory sensitivities determination a large number of elements, possibility to analyzed a solid materials and also smaller (in comparison with HGA type furnaces) some of interferences. Nevertheless in wide analytical practice AAS they till now are not practically used.

This work are presented the results investigation at analytical possibilities of furnace-flame atomizer on AAS determination n·10-5–n·10-4 mass.% Cu, Zn, Cd, Pb, Cr, Fe, Sn, Bi, Sb, Mn in soils, ground settlings, industrial and natural waters, atmospheric particles and some of vegetable materials.

The main particularities of evaporation and atomization process micro amounts of high listed elements are investigated at their transportation from the graphite furnace surface to high-temperature flame (C2H2–N2O for Sn determination and C2H2-air for another elements). The process formation of analytical signals was discussed with estimate of contribution on its value a members of approximately equation:

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nh = 0,280 no (D V h)-1/2 (1)

where nh-effective thickness of atomic absorbance layer; no-quantity

of atoms delivered in flame from furnace surface at one second; D-coefficient of atomic diffusion; V-linear speed of flame gases particles; h-means of flame photometric zone above surface of furnace.

The contribution of parameters a furnace-flame atomizer and some of analyzing materials components in magnitude on value of analytical signal was established.

The results obtained were used at the development of complex simple, accuracy and satisfactory sensitivities (>1 10-5 mass.% high listed elements) AAS method of analysis some of nature waters, soils, sediments, atmospheric air particles and plants.

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SOME APPLICATIONS OF ANALYTICAL CHEMISTRY IN FORENSIC SCIENCES

Salih Cengiz

Institute of Forensic Sciences and Legal medicine Istanbul University, Adli Tıp Enstitüsü Cerrahpaşa, 34303, Istanbul, TURKEY

Forensic analysis is comparative in nature. Two classes of analysis are recognised at the forensic laboratory: (1) screening and (2) legal analyses. In screening, speed and the order of magnitude of concentration are of the essence. The desired data are to be used for forensic treatment or investigation of the source; thus, speed if of the utmost importance. The first category of samples becomes the second as soon as the treatment begins. All positive samples are handled as legal samples if a positive result is obtained. The second category applies to legal cases, in which qualitative and quantitative information, as well as sample integrity are necessary. Legal cases should be identified as such from the outset in order to preserve this distinction.

One of the powerful application of the electroanalytical chemistry in Forensic Sciences is Capillary electrophoresis (CE). CE has recently become an important technique in the separation and analytical measurement in forensic analysis. So that it cover both the screening and legal analyses. Typical examples for the applications of this technique in our laboratories are the characterisation of soil evidences and screening of the toxic sustances in samples of human origin. Simultaneous monitoring of some compounds such as methotrexate (MTX) and 6-mercapto purine (6-MP) in serum, glutathion in red blood cell, Narcotics and other some drugs in urine, and polymer residues in dentistry composite material. MTX is an antifolate drug and has been used together with 6-MP’in treatment acute Iymphocytic leukaemia in children as well as in adult and other childhood malignancies. Glutathion is one of the most important antioxidant agent that protect the red blood cells against the oxidative stress. Therefore and because of the toxicity, separation and monitoring of these drugs and the polymeric residues have vital importance. In this studies a 75 cm long capillary with 70 micrometer ID was chose to separate MTX and 6-MP mixture. The same CE running buffer was chose as Miceller buffer that was contained 30 mM of borate, 30 mM of SDS and 15% acetonitrile with the same mode of the

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capillary electrophoresis for all these studies. Soil samples always appear as important criminal evidences. They can be roughly differentiated and distinguished by their gross appearance. Also distinguishable comparison of colours of wet soil offers a logical first step in forensic soil analysis. But it needs additional assays to distinguish the fine structure by advanced analytical techniques. CE is now been used in many scientific fields of application and currently become a powerful technique for the separation and quantification of ionic substances. Separation speed and direct injection of samples to the capillary without labour intensive sample preparation are the major advantages of the method for the wide variety of real samples. A rough description of a procedure for a forensic CE analysis of a soil sample is as follows: Soil samples were dried in an oven at 1100C and sieved for excluding the rocky particles bigger diameter than 2 mm. 10 g of dry-sieved soil samples were placed in falcon tubes and 10 mL of HPLC grade deionized water was added to each tube. All the samples were shake for 20 minutes and than centrifuged for 10 minutes at 3000 rpm. Supernatants were removed from the solid phase. Then 1 mL of each supernatant was transferred into ependorf tube and centrifuged for 5 minutes at 12000 rpm. The supernatants were transferred into the autosampler vials of the capillary electrophoresis instrument which were programmed to apply triplicate runs for each set of samples and the standards. A commercial system in combination with an on-column variable wawelength UV visible detector and automated sample injector were used for this purpose. The data that were obtained from the analysis of these soil samples have been evaluated. By application of this method one could compare easily the forensic soil samples at least from the CE screening of the chloride, nitrate, sulphate and phosphate anions. So that if a forensic study needs the differentiation of a sample or unification of a particular place or area, or an unknown compound capillary electrophoresis may easily play the most important role at least for logical first step by the anlaysis of ionic composition of the sample.

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DIODE ARRAY DETECTOR ELECTROSPRAY MASS

SPECTROMETRY LIQUID CHROMATOGRAPHY AS APPLIED TO PARTIALLY OVERLAPPING PEAKS.

Richard G Brereton,

School of Chemistry, University of Bristol, Cantock's Close, BRISTOL BS8 1TS, UK

It is now common to obtain information from two or more detectors in HPLC simultaneously. Conventionally both DAD-HPLC and LC-MS data are obtained independently, often using quite different approaches, but there will be common features in both types of information. However, these will be distorted, for example, Electrospray MS profiles are typically more noisy and tailing compared to those from DAD-HPLC due to the different physical processes of passing from the chromatographic column to the detector. A method for obtaining and processing both types of data simultaneously is described. The analysis of isomers with identical molecular weights and similar elution times is particularly important in the pharmaceutical industry where small impurities can have a major influence on biological activity. The approach is illustrated by application to a mixture of 2- and 3-hydroxypyridine at varying levels of overlap.

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COMPARISON OF HIGH PERFORMANCE LIQUID CHROMATOGRAPHY AND GAS CHROMATOGRAPHY/MASS

SPECTROMETRY FOR THE ANALYSIS OF LOW LEVEL OF SOME DRUGS IN BIOLOGICAL FLUIDS

Nursabah E. Başçı1,2_{, Oktay Karadağ}1_{and Aytekin Temizer}1,2

Turkish Doping Control Center1_{and department of Analytical Chemistry,}

Faculty of Pharmacy2_{, Hacettepe University, 06100, ANKARA}

The rising demand for drug testing comes from societies’ pressures to the stem the spread of substances abuse and to provide greater protection to their members. In response to this demand urine analysis testing programmers have been implemented by a wide variety of organization such as business and industrial employers, the transportation industry, police and fire departments, the military and sports.

In order to improve the sports performance (physical, condition, sport skills, muscle strength) administration of the substances and use of methods except natural capacity, exercise and nutrition in called ergogenic aid. Ergogenic aids are physiological (basic salts, blood doping), psychological (hypnosis, stress therapy), mechanic and biomedical (body composition, clothes and material), nutritious (carbohydrates, amino acids, vitamins) and pharmacological substances (banned and permitted). Pharmacological and psychological substances are also called as doping. Doping can be defined as the use by or distribution to an athlete of certain substances that could have the effect of improving artificially the athlete’s physical and/or mental condition and so unfair manner his athletic performance. Doping consists of the administration of substances belonging to the banned classes of pharmacological agents and/or the use of various prohibited methods. Forbidden classes of substances are stimulants, narcotics, anabolic agents, diuretics, peptide and glycoproteine hormones and their analogues. Prohibited methods are blood doping and pharmacological, chemical and physical manipulations. Classes of drugs subject to certain restrictions are alcohol, cannabinoids, local anesthetics, corticosteroids and beta-blockers. Doping classes covers the determination of all these banned groups by using analytical methods based on high technology.

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Mass spectrometry is arguably the most powerful technique for the analysis of organic compounds. It is now applicable to a wide range of different types of analyte with recent developments being particularly concerned with compounds of bioanalytical interest. When the purchase of a mass spectrometry is being contemplated for the first time one of the major consideration is whether to evaluate bench-top instruments which, by definition, have limited performance and upgrade pathways, or to consider and instrument with greater versatility and higher specification.

The decision regarding instrument type will depend upon a number of factors both financial and scientific, arguably the most important in the latter category being the range of analyses for which the instrument will be require in both the short and long term. Similar considerations are appropriate when the existing mass spectrometry facilities within a laboratory require replacing or extending.

This article intended to give some assistance with these deliberations by providing an insight into the ways in which the increased specificity afforded by a modern instrumental techniques such as high performance liquid chromatograph, gas chromatography - mass spectrometer and high resolution mass spectrometry.

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RECONCENTRATION OF SOME TRACE ELEMENTS WITH MICROORGANİSM IMMOBILIZED ON SEPIOLITE

Hüseyin Bağ1_{, A. Rehber Türker}2_{, Mustafa Lale}3

1)_{Pamukkale Üniversitesi, Eğitim Fakültesi, Denizli, TURKEY} 2)_{Gazi Üniversitesi, Fen Edebiyat Fakültesi, Ankara, TURKEY} 3)_{Kırıkkale Üniversitesi, Fen Edebiyat Fakültesi, Kırıkkale, TURKEY}

A method for the preconcentration of Cu, Zn, Fe, Cd and Ni by using some microorganisms (Saccharomyces cerevisiae, Aspergillus niger and Escherichia coli) immobilized on sepiolite as an adsorbent has been developed. The column adsorption method was used for the preconcentration studies. Optimum pH values, amount of adsorbent, elution solution and flow rate of sample solutions for the preconcentration have been obtained for the elements studied. The elements preconcentrated have been determined by flame atomic absorption spectrophotometry. Precision and accuracy of the method have been evaluated. The adsorption capacities of the microorganisms immobilized on sepiolite and limit of detections have also been determined. At the optimum conditions, recoveries of the elements studied were above 95 %. The proposed method has been applied to the determination of Cu, Zn and Fe in geological samples and Fe, and Ni in brass and Cu, Zn, Fe and Ni in aluminum alloy.

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SELENİUM SPECIATION ANALYSIS Krystyna Pyrzyńska

Department of Chemistry, University of Warsaw, Poland

In recent years, there has been increasing interest in the trace determination of selenium. This element has been recognised as an essential nutrient for humans based on its presence in the enzyme glutathione peroxidase, which affords cells protection against oxidative damage. However, selenium reactivity and bioavailability depend not only on its total amount. Additionally knowledge of the chemical forms and oxidation states in which this element exists is

needed.

In environmental and biological samples, selenium can exist in inorganic (as elemental selenium, metal selenides, selenite and selenate ions) and as organic species with direct Se-C bonds (methylated compounds, selenoaminoacids, selenoproteins and their derivatives). Selenate (SeO42-) and selenite (SeO32-) appear to be predominant species in natural waters and soils. The ratio of these two forms depends on the presence of complexing agents, dissolved gases (especially oxygen), suspended matter and pH. Inorganic selenium species can be transformed into volatile compounds such as dimethylselenide (DMSe) and dimethyldiselenide (DMDSe) through microbial action of fungi and plants. The trimethylselenonium ion (TMSe+_), the major product of selenium metabolism, leaves the body of humans in urine. The biomethylation processes are considered to be detoxification steps, because DMSe and TMSe+_{are less toxic than inorganic Se forms.}

Many problems in selenium speciation analysis are associated with low concentration of each species to be determined. Moreover, various factors could affect the losses of Se or interconversion of one species into another during sampling and sample storage could occur.

In natural water samples selenium species in three oxidation states (-II, IV and VI) have been determined mainly by analysing three separate sample aliquots: (1) with no further chemical treatment - determination of Se(IV) using fluorimetry, HG-AAS, HG-ICP-AES or HG-ICP-MS and electrochemical methods; (2) after oxidation by UV irradiation or wet acid digestion - the sum of Se(IV) and Se(-II); and (3) after reduction to selenite with hot hydrochloric or hydrobromic acid - all selenium species. The

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difference between total selenium and the sum of Se(IV) and Se(VI) is attributed to organic selenium compounds. Usually, a preconcentration step (solvent or solid-phase extraction and coprecipitation) is necessary to achieve a sufficient concentration level for detection.

Compared with the extensive investigations on total selenium or selenite and selenate determination, very little work has been carried out on organic selenium compounds. The simultaneous speciation of both inorganic and organic selenium species in a single run is still a great challenge. The direct coupling of HPLC or capillary electrophoresis to selenium-specific detection such as GFAAS or ICP-MS is the most promising approach for the determination of selenium species in biological and environmental samples.

This lecture has neither the intention of covering all published methods for selenium speciation, nor of critizing specific scheme. It would rather discuss some general ideas and highlight some important procedures.

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USE OF SURFACE ENHANCED RAMAN SPECTROSCOPY (SERS) IN BIOANALYTICAL CHEMISTRY

Mürvet Volkan

Department of Chemistry, Faculty of Art and Sciences, Middle East Technical University, 06531- Ankara,

murvet@metu.edu.tr

Raman spectroscopy is an analytical method that offers several important advantages. This technique provides a rapid and non-destructive analytical tool. It yields highly compound-specific information for chemical analysis, and has great potential for multi-component analysis. The Raman technique also requires little sample preparation, which allows on-line analysis and field applications. One limitation of conventional Raman spectroscopy is its low sensitivity, often requiring the use of powerful and costly laser sources for excitation. However, discoveries in the late 1970s indicated that Raman scattering efficiency could be enhanced by factors of up to 106_{when a compound is adsorbed on or near special metal surfaces.} The technique associated with this phenomenon is known as surface-enhanced Raman scattering (SERS) spectroscopy. Raman and SERS spectroscopy for the detection of hazardous chemicals, such as environmental pollutants, explosives, and chemical warfare agents or simulants, has been reviewed (1,2). Raman spectroscopy is rapid, non-destructive, and highly compound-specific. This technique has multi-component analysis potential and requires little sample preparation, which allows on –line and in-field analysis.

In this seminar two recent bioanalytical applications of the SERS, namely dopamine determination and DNA mapping. will be presented. References

[1] T.Vo-Dinh. “Surface-Enhanced Raman Spectroscopy”. In Photonic Probes of Surfaces, P.Halevi, Ed., Elsevier, New York (1995). [2] A. Ruperez and J.J Laserna,” Surface Enhanced Raman Spectroscopy”

in, Modern Techniques in Raman Spectroscopy,1996, Wiley, New York (1996)

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CAPILLARY ELECTROPHORESIS AND APPLICATIONS

F. Bedia Erim Berker

Department of Chemistry, Technical University of Istanbul, 80626, Maslak, Istanbul, Turkey

E-mail: erim@itu.edu.tr

Capillary Electrophoresis(CE) is today the most rapidly developing area in separation science. The fast and effective separation given by CE, its on-line detection system, its small sample(1-50nL) requirements, and the diverse separation modes have greatly contributed the large domain of applications.

In CE, separation takes place inside silica capillary tubes with internal radius between 20-75µm. The two ends of the capillary are immersed into two buffer compartments that also contain the electrodes. The sample is injected at one end of capillary, is separated under an applied high voltage (up to 30kV), and is detected at the other end of the capillary. Due to the double layer that forms on the internal surface of the capillary by the surface ionization of silica, an electroosmotic flow towards the cathode occurs under the applied voltage. Under this electroosmotic flow, all injected ionic and non-ionic material are diferently driven towards the cathode, thus separated and on-line detected.

Capillary zone electrophoresis (CZE), capillary gel electrophoresis (CGE), capillary electrochromatography (CEC), and micellar electrokinetic chromatography (MEKC) are the common variants of CE:

This paper presents a review of our researches on CE: The research results are organized into four major sections-The analysis of fatty acids by MECK, the use of polymers in CE, separation of metal ions by CE, and affinity analysis by CE.

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SOME SPECIATION STUDIES IN FOODSTUFF BY ATOMIC ABSORPTION SPECTROMETRY

S.Gücer

Uludag Universitiy Faculty of Science and Arts Department of Chemistry.,16059-Bursa/Turkey

There has been increasing interest in speciation studies of essential elements in foods. The main limitation of this studies, their levels in food samples and the difficulties for the determination in their own different forms without any changes in their original forms.

Atomic Absorption Spectrometry (AAS) coupled with separation methods would be outline in this presentation.

Analytical scheme was given for tea, olive and garlic samples for Manganese, Magnesium and Selenium respectively. Activated carbon, solvent extraction, solid phase extraction as well as co-precipitation methods will be discussed for speciation studies.

Because its sensitivity Electro-thermal AAS is the preferable technique if the levels in ppb range. Some of the interference problems would be given for the accuracy of the total element determinations.