Abstract In this report we describe our experience in theanalytical chemistry curriculum of teaching spectrometerprinciples and preparing spectroscopy laboratory exer-cises by means of virtual instruments. The benefits of theintensified preparation of laboratory exercises by virtualinstruments will be evaluated with respect to the subse-quent handling of real instruments. The utilization of in-house electronic media with Internet resources for eluci-dation and verification of a structural assignment will alsobe considered.

Introduction

The explosive growth of the internet in recent years willnot only change chemical science but also chemical edu-cation. It is not simply remote access to certain types ofspectrometers at smaller universities, who can no longerafford to have the full range of instruments available. Re-mote collaboration clearly extends to mutual explorationof chemical expertise, to scientific data and tools. Firstlessons learned by sharing instrumentation are about to beextended to sharing expertise and data. Modern spectrom-eters – at least those controlled via a computer keyboard –can be simulated particularly well. Virtual instrumentsmust, on the other hand, never become a substitute forhands-on experience in real laboratory courses.

Simulations of the complex behavior of matter are verywell appreciated nowadays. Such simulations, e.g., by

molecular modeling, are regarded as important means ofimproving our understanding of chemical processes. Onthe other hand, simulations of the complex principles oflaboratory instrumentation still runs up against certain re-straints. Virtual instruments might be used to reinforce theeducational process from college curricula to trainee pro-grams in industry. Virtual spectrometers are, to some peo-ple, “just another collection of glitzy video tricks”, as P. B. Farnsworth reported in a recent editorial [1]. How-ever, the author expects, “virtual instruments used in com-bination with hands-on experience could be powerfultools for teaching spectroscopy” [1]. In this report we aredescribing our experience with exactly this combinationof virtual and real spectroscopic experiments.

Another prejudice against the utilization of the internetfor education is discussed in a recent issue of the regularWebWork column of Analytical Chemistry [2]: “Is the Internet Keeping the Scientist away from the Benchtop?”It rather turned out that spectroscopists are gainfully mining the Internet for all kinds of information, and thetrend will continue [2]. For the curricula of today’s stu-dents it must be concluded that hands-on experience hasto be extended to the access of world-wide availableknowledge – going further than taking advantage of vari-ous library services or simply searching for a particularspectrum in one of the accessible data banks. Hands-onexperience is no longer restricted to laboratory instrumen-tation. Teaching using internet-assisted exercises in mole-cular spectroscopy certainly meets a need of the profes-sional future.

In the educational complex for molecular spectroscopydescribed in this report, at first the student is offered a the-oretical chapter. Subsequently, a virtual spectrometer canbe used to select appropriate recording conditions. Theseoptimized conditions will be used to measure spectra ofan unknown substance on a real spectrometer. Afterwards,the structure of the unknown will be elucidated by use ofIR, Raman, and UV–Vis spectra acquired during the labo-ratory course. Supplemental MS and NMR spectra areplaced at the student’s disposal. The final feature of thisspectroscopic experiment is verification of a proposed

H. Thomas · S. Paasch · S. Machill · S. Thiele ·K. Herzog · M. Hemmer · J. Gasteiger · R. Salzer

Internet-assisted exercises in structural analysis

Fresenius J Anal Chem (2001) 371 :4–10DOI 10.1007/s002160100842

Received: 16 January 2001 / Revised: 8 March 2001 / Accepted: 13 March 2001 / Published online: 12 July 2001

TUTORIAL REPORT

Dedicated to the memory of Professor Dr. J.F.K. Huber to commemorate his contributions to the development of analytical chemistry

H. Thomas · S. Paasch · S. Machill · S. Thiele · K. Herzog ·R. Salzer (✉ )Institute of Analytical Chemistry, Dresden University of Technology, 01062 Dresden, Germanye-mail: reiner.salzer@chemie.tu-dresden.de, Fax: +49-351-4637188

M. Hemmer · J. GasteigerComputer Chemistry Center, University of Nuremberg-Erlangen, 91052 Erlangen, Germany

© Springer-Verlag 2001

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structural formula by simulation of the IR spectrum usingremote resources.

Requirements

Those attending the internet-supported laboratory exer-cises in instrumental analytical chemistry have to applybasic knowledge in computer applications in chemistrysuch as Microsoft Office and common programs for draw-

ing simple graphs and chemical structures. In a precedingcomputer course the students have to pass an exam to ver-ify their ability to exchange data electronically, to docu-ment their practical results in digital protocols, and to useelectronic databases in chemistry at a beginner’s level.

The current laboratory course in analytical chemistrycomprises 13 real experiments covering all major parts ofinstrumental analysis. It constitutes a significant part ineducation in chemistry at the Bachelors level. The stu-dents prepare all experiments individually at their remote

Fig.1 Appearance of the IRspectrometer, during the virtualspectroscopic experiment, inthe window of a web browser.The spectrometer controls andthe environment on the work-bench must be explored on thescreen by use of the mousepointer

Fig.2 Image map of the con-trol panel of the virtual spec-trometer. The control panel isidentical to the FTIR spectrom-eter used during the real labo-ratory exercises (Nicolet 205).The buttons are explored bymeans of the mouse pointer.Only buttons relevant to thelaboratory exercises are acti-vated for use during the explo-ration

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Fig.3 A sequence of animatedphotographs illustrates crucialsteps in the preparation of aKBr pellet. The student can ad-just the frame speed of the in-dividual photographs

terminal. They log in to the institute’s homepage [3] anduse the educational material provided, which covers pho-tos, animations, and videos. Photographic sequences aboutdifficult steps in sample preparation and virtual instru-ments closely relate the preparatory phase to the real ex-periments in the subsequent practical course. Spectra ofan unknown substance can be acquired using the pre-opti-mized settings.

Results

After the students have worked through a theoretical chap-ter of the on-line course materials, a spectrometer will bedisplayed on the student’s terminal. In this report we shallfocus the discussion on the virtual IR spectrometer, forwhich we have accumulated the most extensive experi-ence (Fig.1). On their screen, the students explore the in-strument and the workbench environment using themouse pointer. Particular considerations for occupationalsafety may pop up if necessary.

To proceed with the measurement, a keyboard to con-trol the IR spectrometer is brought up (Fig.2). Only but-

tons necessary for the current experiment need to be acti-vated. Those buttons have to be identified by the studentusing the exploratory mouse pointer. After the spectrome-ter has been explored the student becomes acquaintedwith sample preparation. Challenging steps of the processof sample preparation, e.g., the preparation of a KBr pel-let (Fig.3), are provided as a series of animated images.The goal of this part of the experiment is to familiarize thestudent with a variety of techniques for collecting IRspectra of gases, liquids, and solids. Settings such as theappropriate resolution or a meaningful number of scansmust be chosen. The importance of the background spec-trum to the quality of the final result is emphasized.

Upon completion of the virtual IR experiment, the stu-dents must reveal their knowledge by answering severalquestions found in the on-line material. Every student isallocated individual questions, randomly selected from alarge pool of questions. The answers to this little exam aresent via e-mail to the staff assistant responsible for thereal exercise in the laboratory. Each electronic exam isfollowed by an oral exam, immediately before the practi-cal exercises. The oral exam must be passed before thestudent can be admitted to the labs, where spectra of an

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Fig.4 Set of molecular spectraof an unknown. IR, Raman,and UV–Vis spectra measuredby the students during previousexercises are assembled andsupplemented by MS andNMR spectra

unknown will be taken. The spectra acquired – presentlyby IR, Raman, and UV–Vis spectroscopic techniques –are supplemented by MS, 1H-NMR, and 13C-NMR spectraand pooled. The latter spectra must be supplemented, be-cause our Bachelor students do not perform their ownmeasurements by NMR and MS. An example of a com-

plete set of spectra is given in Fig.4. The target compoundis 8-hydroxyquinoline. The structure evaluation consti-tutes the student’s final task in this exercise.

Initially the spectra evaluation process is based on con-ventional methods of structural analysis by means of ta-bles and handbooks. Subsequently some on-line databanks and spectral libraries are included in the evaluationprocess, with the on-line steps being supervised by thestaff. On completion of this part the students propose anestimated structure for the unknown. Often the studentsare unable to verify their suggestion, because they do notfind a reference spectrum in an accessible spectral library.To overcome this restriction we included into our labora-tory course a telecooperation via internet. The studentslog-in at the web site of the Computer Chemistry Centerat the University of Erlangen [4]. The program TeleSpecwas developed in the framework of the project “Telecoop-eration in Spectroscopy” [5]. It includes a tool for the sim-ulation of IR spectra. The proposed structure of the un-

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Fig.5 Simulated IR spectrum as it is returned from the remoteserver. The dominant features of the simulated spectrum and theexperimental IR spectrum (cf. Fig.3) must be compared to validatethe proposed structure of the unknown

Fig.6 Desktop appearance of an on-line discussion via the inter-net using the videoconference system. The lower left shows the so-called whiteboard. It can be accessed simultaneously via all partic-ipating terminals for instant exchange of drawings and text. Theremote control of the videoconference system is placed in thelower right corner. The current speaker is seen in the upper rightwindow. The upper left part is used to explain to the students howthe program TeleSpec is efficiently accessed

known is submitted via a common structure editor. On theremote server, the 2D structure of the query molecule isconverted into a 3D structure by the program CORINA.Several 3D functions (vision, rotation, zoom, and transla-tion) enable the students to obtain an idea of the spatialfeatures of their proposed molecule.

The simulation program for IR spectra is based on aneural network algorithm [5, 6, 7]. Even during periods ofhigh network use the program returns spectra of sufficientquality after only a few minutes. In comparison, a semi-empirical simulation of an IR spectrum of molecules withonly 20 atoms requires several hours. Ab-initio calcula-tions provide superior results, but the computing time iseven longer.

As a result of the simulation procedure the students ob-tain a color-coded map which depicts the trained neuralnetwork for their query molecule. The IR spectrum corre-lated to the winning neuron is also returned (Fig.5). Bycomparing the main features of the experimental and sim-ulated spectra the students are enabled to validate theirelucidation results and, if necessary, to revise their pro-posed structural formula. By comparison of structurecodes and IR spectra of neighboring neurons, the studentswill obtain additional information about the spectrum–structure correlation. Modifications of the substructureswill finally lead to the correct result. A videoconferencingsystem is intended to support the last step of the labora-tory exercise in structure elucidation (Fig.6).

Discussion

The internet-assisted exercises in instrumental analyticalchemistry described in this report are an integral part ofthe project “Network in Education – Chemistry” [8], inwhich eight German universities participate, among themtwo universities with contributions to analytical chemistry[3, 9]. Probably the most important concern in the devel-opment of this part of the network for education is the re-lationship between virtual instruments and real experi-ments – multimedia must never replace any practical ex-ercise in handling a sample. Instead, a virtual laboratorycan most advantageously be used to reinforce the teachingof complex principles of instrumentation and evaluation.

Our first experiences in developing multimedia mater-ial for molecular spectroscopy as one of the most impor-tant areas of instrumental analytical chemistry date backto 1995. Since then it has been reconfirmed in all classesthat multimedia tools enable the student to prepare effec-tively for the real exercises by practicing beforehand atvirtual instruments and/or by simulating potentially dan-gerous experiments. Interactive documents enable the stu-dent to progress according to his/her individual needs orabilities, to repeat parts of the material, or to include in-formation from other scientific areas. The student will betrained to work in an interdisciplinary fashion and to com-bine different techniques, e.g., to apply different spectro-scopic techniques to solve a given task. Hazardous situa-tions for people, instrumentation, or environment during

subsequent laboratory work can be largely prevented inthis way.

The experiment involving determination of the struc-ture of an unknown is very well accepted by the students,who acknowledge the practical importance of the educa-tional task. In more conventional approaches they onlylearn to solve a given problem by means of handbooksand printed reference tables. The immediate verificationof the derived structural assignment increases their desireto obtain a reasonable result. They also derive hands-onexperience of the advantages and limitations of electronicdatabases. Of course, the resources available to the stu-dents are restricted to merely a small part – such as Spec-Tool (Chemical Concepts, Weinheim/Germany) or Tele-Spec [4] – of that available both commercially and non-commercially, but hands-on experience gathered even at arelatively low educational level can be easily extended bythe students in subsequent exercises during their Mastersstudies, when more comprehensive facilities are provided,including tools like Masslib (MSP Friedli, Koenitz/Switzerland) or SpecInfo (Chemical Concepts, Weinheim/Germany).

The student’s particular benefit from the exercise re-ported here is the chance to use all computer resources si-multaneously. The usual problem for teachers remains,i.e., substances particularly suited for this kind of experi-ment have to be allocated. One particular requirement isthe occurrence of an adequate number of different struc-ture groups in the molecule. Preferably, the substanceshould also be non-toxic. Standard preparation proceduresand standard scan parameters should, furthermore, be suf-ficient to enable acquisition of spectra of a standard qual-ity. All in all, the experiment requires much effort by thestaff – the students must be supervised extensively and in-tensive cooperation between the teachers in charge of dif-ferent spectroscopic methods is necessary.

The web documentation enables the student to accessthe required information from anywhere, either whileworking in the laboratory or while studying at home. Theenormous capabilities – nowadays provided even by astandard computer – enable interactive learning, which ismore effective and more encouraging to the student thanthe traditional gathering of facts. A virtual experimentmight also help to abolish the anxiety sometimes observedbefore a real experiment is performed on expensive equip-ment.

Irrespective of the technical means used, it is importantfor students and teachers to develop a level of personalcommunication. Information exchange via e-mail and theWWW is very useful and effective, but it must not be-come the only means of communication. Students can, onthe other hand, advantageously use the internet to com-municate personally with experts at a remote location.

It seems that multimedia applications have a positiveinfluence on learning motivation. Finding information viathe internet is more effective, faster, cheaper, and (whichshould not be forgotten) might add some fun to the trou-bles in trying to solve a challenging problem. Despite thefun factor, it might be necessary to remind some designers

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of internet pages that information has to be the main con-tent. The user must, moreover, have to have the choice ofwhich of the larger multimedia files she/he needs andwants to download.

Conclusion

It has been proven during the last six years that virtualspectroscopic experiments have a distinct positive influ-ence on learning motivation. The students progress undervery controlled conditions and at the same time are pro-vided with much more freedom to explore technicalboundaries, to perform and repeat experiments. The vir-tual exercises, which precede real laboratory exercises,contribute substantially to the prevention of hazardous sit-uations for people, instrumentation, and the environment.

In structural analysis, as in any field of education, tra-ditional approaches in teaching have to be balanced withmore advanced on-line achievements. There is, of course,also a learning curve for designers and providers of re-motely accessible information. The situation is technol-ogy-driven. To benefit their professional future, the stu-dents must become familiar with all the implications ofthat development as early as possible. Laboratory exer-cises in structural analysis are particularly well suited tointroducing the students to advanced internet-assistedtechniques. The complete process from sample prepara-tion via instrumental analysis to spectra evaluation can becovered by one unified exercise.

Internet-assisted exercises do not only ease the learn-ing process, they contribute substantially to providing thestudents with the ability to keep up with new develop-ments – both scientific and technical. New technologiesfinally lead to an improved employability, which in turn isthe main goal of on-going reforms in universities.

Acknowledgement The project “Network for Education – Chem-istry” (Vernetztes Studium – Chemie) has been selected as a prior-ity project by the German Ministry of Education and Technology(BMBF). Financial support by the BMBF facilitated the substan-tial development of our previous efforts. Cooperation in the frame-work of the “Network for Education – Chemistry” is technicallysupported by the Fachinformationszentrum Chemie Berlin. Wethank the chemistry and food chemistry students of the DresdenUniversity of Technology for their critical evaluation of the multi-media material. Financial support by the “Fonds der ChemischenIndustrie” is greatly appreciated.

References

1.Farnsworth PB (2000) Appl Spectrosc 54:156A2.Bradley D (2000) Anal Chem 72:489A3.http://analyt.chm.tu-dresden.de4.http://www2.ccc.uni-erlangen.de/research/ir/english/index.html5.Selzer P, Gasteiger J, Thomas H, Salzer R (2000) Chem Eur J

6:9206.Zupan J, Gasteiger J (1993) (eds) Neuronal Networks for Chem-

ists – An Introduction. VCH, Weinheim7.Gasteiger J, Zupan J (1993) Angew Chem 105:5108.http://www.vernetztes-studium.de9.http://barolo.ipc.uni-tuebingen.de