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tion of unusually low fluorophore concentrations appears possible in certain cases where energy transfer form analyte to fluorophore gives a (positive) signal. Some improvements of sampling from single nerve cells from Plunorbis cur-new were shown by Ewing. Picoliter injections are made with the sharp etched tip of a 5-~1 separation capillary. A lo-lOO-fold improvement in detection limits with an array mass detection system as compared to a conventional electron multiplier detection system in CE with a continuous flow fast atom bombardment (CFFAB) interface was presented by Van der Greef. The use of CE-mass spectrometry (MS) and CE-MS-MS with an electrospray interface for peptide mapping with impressive performance for high masses was shown by Smith. Radioactivity detection offers the possibility of improving detection limits by lowering the flow-rate at the moment an analyte passes the detector in order to increase the counting time. Applications The use of gel-filled capillaries for

DNA sequencing was a major topic presented by Karger and in more detail by one of his co-workers Cohen. A total number of five out of eight presentations in the Tuesday sessions Oligonucleotide Analysis and Applications Z was devoted to this subject. According to Drossman, DNA “CEquencing” could shorten the time needed for mapping of the human genome from a thousand man years with conventional methods, to a minimum of fourteen man years. An interesting application of high speed separations was presented by Jorgenson, who employed a high intensity laser beam at the inlet of a 4cm (10 pm I.D.) capillary to permanently degrade the fluorescence label of amino acids that were introduced continuously into the separation capillary. By interrupting the laser beam for a few microseconds, an extremely small amount of the analytes were not exposed to the degrading laser beam, implying that the labeled amino acids were injected and could be separated. Fluores-

cence detection took place using a second low intensity laser beam after separation within a few seconds. Another growing field of interest is the analysis of carbohydrates. Honda demonstrated how uncharged carbohydrates can be separated after complexation with borate ions or by the application of derivatizing agents. Theory The influence

of several parameters on peak capacity, defined as the maximum number of peaks in a given period of time, was discussed by Grushka. It was not surprising that low buffer concentrations and small I.D. capillaries appeared to be favourable. Hjerten presented an equation for the optimum fieldstrength (F). By plotting the several factors responsible for band broadening in CE as a

function of F squared, the optimum fieldstrength can be derived. Nielsen used the molecular weight and calculated charge of peptides in correlation with the electrophoretic mobility to optimize the separation. In conclusion it can be stated that HPCE will become an important tool in modern analytical laboratories but considerable input still has to be given to the development of the different building blocks. The research interest in this field is growing so fast that major improvements can be expected in the near future. The next symposium, to be held in San Diego in 1991, is eagerly awaited. N. J. REINHOUD N. J. Reinhoud is at the Divkion of Analytical Chemistry of the Center for BioPharmaceutical Sciences of the University of Leiden, The Netherlands.

Hyphenated techniques in chromatography

1st International Symposium on Hyphenated Techniques in Chromatography, Antwerp, Belgium, 22-23 February, 1990. The 1st Symposium on Hyphenated Techniques in Chromatography welcomed over 200 scientists, from both academia and industry. The opening lecture by Prof. Cramers, Eindhoven University, illustrated modern trends in miniaturization and hyphenation of chromatographic techniques. By using ‘reduced’ parameters, i.e. dimensionless parameters which apply to all aggregation states, a comparison was made between gas chromatography (GC), supercritical fluid chromatography (SFC) and high-performance liquid chromatography (HPLC). The reduced analysis time, for example, clearly illustrates that capillary gas chromatography (CGC) will always be the faster technique. Miniaturization of LC and SFC to achieve analysis times comparable to CGC creates either technical problems (for LC one would

need to use 5 ,um I.D. columns) or chromatographic problems (the pressure drop in SFC influences the density, i.e. the partitioning process). From a column-detector compatibility point of view, the low sample capacity of microbore columns imposes strict requirements on detector characteristics. A typical example is the Fourier transform infrared (FT-IR) detector: because of its high time constant (ratio cell volume-speed) , FT-IR is compatible neither with the high speed nor with the low sample amounts of ,KGC. Detector considerations in this case enforce the use of micropacked columns . For fast chromatography, i.e. using 10 pm I.D. columns, even conventional mass spectrometry (MS), including electronics and data systems, is too slow. Dr. Leclercq, Eindhoven University, described a mass spectrometer for simultaneous detection of ions. This impressive set-up uses a micro channel plate (MCP) array detector and a special ion multicollector system for simulta-

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neous recording, and is capable of acquiring spectra in less than 10 milliseconds or 100 spectra per second. In terms of sensitivities, identification can be carried out on femtogram or even attogram sample amounts. A specific CGC-MS application, the determination of carbon isotope ratios from GC-eluates, was presented by Finnigan MAT. Rather than carrying out isotope ratio determinations as a group parameter on oxidized samples, the effluent tube of a capillary GC column is fed online into a micro-combustion furnace of 0.5 mm I.D. After removal of the water by a permeable membrane separator, the carbon dioxide generated from each GC peak is fed to the ion source of the mass spectrometer through a conventional open split interface. The mass spectrometer continuously records the CO, masses 44, 45 and 46 in a triple Faraday cup collector. A precision of more than 0.00035 at.% is obtained. Applications include the analysis of biomarkers in oils (pristane, phytane), detection of flavour adulteration and the analysis of drug metabolites. Interfacing SFC to FI-IR was discussed by Mr. Belz, Nicolet Instruments. The interface itself can be rather simple, maintaining temperature and pressure above the critical temperatures of the mobile phase (e.g., T > 31 “C; P > 73 bar for CO,). Using a 1.4~~1 cell that withstands pressures up to 400 bar, detection limits of 10 ng (for a-tocopherol) are claimed. However, the comparison of generated spectra to IR library spectra can be a problem, because of the different pressures under which the spectra are generated. Shifts of up to 10 wavenumbers, in either direction, can occur. Because spectrum shifts do not occur in helium, Dr. Bartle, University of Leeds, suggested its use as a make-up gas. It would be even better to use xenon rather than CO, as a mobile phase as xenon has similar or better solvent characteristics than carbon dioxide, and adequate transport properties for chromatography. Since xenon is totally transparent in the IR region, it is an ideal medium to analyse, for example, hydroxyl, nitrile, isocyanate, aromatic C-H

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deformation and C-Cl deformations, which are normally masked by the carbon dioxide absorption bands. Coupling SFC to MS was described by Dr. Hoefler , Dionex GmbH. The interface must maintain the high pressures (400 atm) in the SFC column. To avoid cluster formation due to the cooling effect when expanding to MS pressures of 10d6 Torr, the interface must be heated. However, the occurrence of hot spots must be avoided. Increased temperatures result in decreased densities, i.e. solubilities. Differently shaped interfaces (linear restrictor, tapered restrictor, Guthrie restrictor) can overcome these problems to a certain extent. There is a pending problem, however, relating to the interaction of CO, with the ionization pattern in the MS. Charge exchange ionization or even mixed electron impact-chemical ionization (EI-CI) spectra can be generated. Present studies attempt to utilise these ionization phenomena in structure elucidation . Coupling liquid phase separation methods (LC, SFC, CE) to MS often creates problems with respect to the nature of the solvent used, or the use of non-compatible additives. Dr. Niessen, Center for Bio-Pharmaceutical Sciences, The Netherlands, described a phase switching system (PSS). In a PSS, the components of interest are trapped on a column, subsequently washed out and transferred to the MS interface with a suitable solvent. The approach is also useful when aqueous samples have to be injected in SFC, as the PSS can be positioned before the analytical column. VG Masslab presented a new HPLC-MS interface for a triple quadrupole mass spectrometer. The interface operates at atmospheric pressure (API, atmospheric pressure ionization), thus avoiding problems associated with introducing liquids directly into vacuum. Moreover, electrospray ionization generates singly and multiply charged ions, allowing the analysis and molecular weight measurements of large molecules such as peptides and nucleotides (up to tens of kilodaltons). A GC-FT-IR interface, Tracer,

was presented by Bio-Rad Digilab Division. The Tracer used cryogenic trapping of the capillary column eluent on an infrared-transparent window which serves as a sample storage device. This window is translated with a precision XY motorized stage so that the chromatogram is collected as a narrow line. Transmission spectra are recorded, giving an efficient real-time run. Tracer typically deposits the sample in a 0.25-0.30-mm track. By matching the optics to the sample size, large absorbances are achieved from minute quantities of sample. The most recent development in hyphenated spectroscopic techniques, the atomic emission detector , was described by Dr. Bandemer , Hewlett-Packard, F.R.G. When entering a microwave induced plasma, all components of a GC column effluent are atomized immediately. The excited atoms emit element-specific light of distinct wavelengths. With a high resolution photodiodearray spectrometer, containing 200 photodiodes, several element specific chromatograms can be recorded simultaneously. Using a movable grid, the optical resolution can be increased so as to allow the differentiation between different isotopes (lH-*H, ‘*C-i3C). The detector offers very interesting possibilities for petrochemical industries (sulphur, nitrogen, nickel, vanadioxygen, um), in environmental analysis (differentiation between halogenated compounds) and in food, flavour and aroma research. As different elements can be monitored simultaneously, the atomic emission detector (AED) allows the calculation of the empirical formula of unknown components: an interesting feature for mass spectrometrists. Moreover, component independent calibration becomes possible with the AED. A review on the possibilities of multidimensional CGC was presented by Dr. David, Research Institute for Chromatography, Belgium. The potentials of coupled LC-GC were illustrated by Dr. Grob, Kantonales Labor, Zurich. A case study on the adulteration of olive oil clearly illustrated the potentials of on-line LC-GC coupling. The on-line cou-

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pling is achieved through a sample loop, combined with a 2-m retention gap in the GC system. A preseparation in the LC system, followed by GC analysis of the sterol fraction, is capable of differentiating between three different grades of olive oil. The closing lecture by Dr. Sandra, University of Ghent , reviewed trends in hyphenated techniques. In the future, hyphenated techniques will mainly deal with improving the integrity of the spectral information when dealing with qualitative analy-

sis. For quantitative analysis, the demands on the interface are very high with respect to transfer efficiency and the inertness of the system. Developments are to be expected in the field of sample preparation hyphenations: on-line supercritical fluid extraction-capillary gas chromatography (SFE-CGC) equipment is already commercially available. Some interesting applications of j4LC (size exclusion)-CGC were presented. This 1st International Symposium

on Hyphenated Techniques in Chromatography was a success, both scientifically and from an organizational point of view. The 2nd International Symposium on Hyphenated Techniques in Chromatography, to be held in Antwerp, 18-21 February 1992 will undoubtedly feature a large number of interesting developments, G. REDANT Dr. G. Redant is at Recorder bvba, P.O. Box 79, B-8610 Wevelgem, Belgium.

APL as a development language for multivariate spectroscopic applications D. F. Wirsz Vancouver, Canada

APL is a convenient language for rapid development and evaluation of multivariutemethods of data analysis. Its predecfined vector and mutrix operations, and the abilityto build more complex programs from these and other operations, make APL particulurly suited to spectral analysis. Examples are presented from programs in current use. Introduction When new multivariate methods are applied to spectroscopic problems, algorithms must be evaluated, and many programs are written and rewritten during this development process. APL (A Programming Language) is a useful language for such development and has therefore found a small but important niche among the ‘mainstream’ computing languages. Originally developed in the 1950’s as a method of notation for mathematical operators, it was implemented in the 1960’s as a real programming language on IBM mainframes, and soon became available as a time shared service. Throughout the 1970’s it was very popular on university mainframes’, and in the 1980’s became established on the IBM PC. Several APL programs are used in this laboratory for the manipulation of spectra collected from a 4096 01659936/90/$03.OQ.

segment photodiode array. These include factor analysis methods to determine the number of elements in a multielement sample2, and algorithms to select the most suitable line for analysis, on the basis of freedom from spectral interference, without reference to tables of spectral emissions3p4. The advantages of APL as a development language will be illustrated through several examples derived from these programs. Upon beginning an APL session, the user is presented with an operating environment called a workspace. Within this workspace, the user can enter data into variables which may be scalars, vectors, or matrices. The data can then be manipulated using a large number of predefined mathematical operations. Commands may be entered one line at a time (which is particularly useful when creating or investigating an algorithm) or they may be combined into a program (called a function in APL) which will then carry out the sequence of commands automatically. In the former case the operating environment is much like that of a calculator. In the latter case user interaction may be customized with the use of prompts and selection menus. A complete list of defined variables and programs is always available to the user. Predefined mathematical operations include all those commonly found on scientific calculators, and 0

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