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Meeting report: 2nd workshop on liquid chromatography—mass spectrometry
VII
trends in aqalytical chmistry, vol. 2, no. 6, 1983
MEETING REPORTS
Interfacial topics A report on the 2nd Workshop on Liquid Chromatography-Mass Spectrometry, held in Montreux, Switzerland, 21-22 October 1982 Two relatively new analytical techniques, liquid chromatography-mass spectrometry (LC-MS) and tandem mass spectrometry (MS-MS), were the focus of interest at the recent 2nd workshop on LC-MS. The workshop was organized by the International Association of Environmental Analytical Chemistry and coordinated by Frei (Amsterdam), Guiochon (Paris) and Nibbering (Amsterdam). The topics covered were the one-line combination of high performance liquid chromatography (HPLC) with mass spectrometry (MS) and the coupling of MS with a second MS analysis. Three lectures gave overviews on the subjects. Fenselau (Johns Hopkins University) covered recent advances in soft ionization techniques for MS. These include chemical ionization, field desorption, laser desorption, Cf-252 plasma desorption, secondary ion MS, fast atom bombardment, electrohydrodynamic ionization, thermospray techniques and solvent evaporation from preformed ions. Guiochon and Arpino (Ecole Polytechnique, Paris) focused on the requirements made by the chromatographic system on the mass spectrometer, such as the need for both qualitative and quantitative information and a fast response time which preserves the chromatographic integrity. Huber (University of Vienna) examined the coupling of two analytical techniques from the view-point of information theory. Huber concluded that more information is obtained by coupling two dissimilar chromatographic separations than by coupling chromatography with MS.
Interfaces In recent years, several interface principles have been developed for coupling HPLC and MS in order to obtain, for non-volatile compounds, the same structural data and selectivity in detection which gas chromatography (GC)-MS provides for more 0165~9936/&/$01.00
volatile analytes. These interface systems were well represented by researchers actively involved in their application and development. Games (Univesity College, CardifI) and others presented recent results with LC-MS using transport systems. These were first introduced commercially by Finnigan and employ a moving wire or belt which carries the LC efIluent into the MS vacuum system through a series of vacuum locks, removing most of the solvent on the way. Advances in this approach include the use of miniaturized liquid chromatography (LC) systems which minimize the need for the removal of large amounts of solvent by IR radiation (which can lead to sample decomposition) and which allow rapid analyses to be performed. A variety of ionization techniques used in conjunction with ‘the belt’, such as chemical ionization, electron impact and fast atom bombardment were also discussed. Benninghoven (University of Miinster) discussed the coupling of belt systems with secondary ion MS (SIMS). This system shows good sensitivity (1 O-l2 mol) as an LC detector but has some problems which result from variation in the sample ionization probability due to the chemical environment, i.e. the mobile phase. A second LC-MS interface system, direct liquid introduction (DLI) was discussed by Henion (Cornell University), Arpino (Ecole Polytechnique, Paris) and others. The DLI probe operates by introducing up to 40 ~1 of liquid directly into the MS ionization source. Advances in these systems include: the use of miniaturized LC in which the total LC effluent can be introduced into the MS, increasing the sensitivity of the technique; the use ofa de-solvation chamber between the DLI probe and the ion source, which serves to enrich the sample with respect to the solvent; and the analysis ofpreformed ions, in which no separate ionization technique is required. A third type of interface was described by Christensen (US National Bureau of Standards) which uses a heated wire, along which the LC
effluent flows while the solvent is evaporated and the sample enriched. The sample is then fed into the MS ion source via an ultrasonic nebulizer which utilizes magnetothe constrictive properties of a nickel wire to produce the necessary ultrasonic vibration. An interface which couples HPLC with an MS system utilizing Cf-252 plasma desorption and a time-of-flight mass-spectrometer was described by Jungclas et al. (Philipps University, Marburg). This interface consists of a disc which rotates to collect effluent fractions from the LC. The fractions thus stored can be rotated into the ionization source and analysed by MS. A similar device was presented by Heresch and Huber (University of Vienna) which uses a small indented rod to collect fractions for laser desorption MS. An interesting panel discussion, organized by Martin (Glaxo Ltd.) compared the use of the DLI and moving belt interfaces in a ‘roundrobin’ analysis of the drug ranitidine and its metabolites. Of the results presented, the analysis using the DLI interface by Dixon (Hewlett-Packard) showed advantages over the other analysis using the belt transport system, particularly for thermally labile metabolites. The subject of MS-MS was addressed by Hunt (University of Virginia), who presented very convincing arguments for the use of triple quadrupole systems in the screening of complex matrices. The triple quadrupole separates individual components as molecular ions in the first quadrupole MS. Fragments (or ‘daughter ions’) are subsequently produced in a second quadrupole mass filter by collision activated disssociation, and these are analysed in a third quadrupole. The screening of all the U.S. Environmental Protection Agency priority pollutants in under 30 min per sample was presented as an example. Several other papers were given on the subject, indicating the growth of interest and application of this new technique. The workshop was preceded by a P-day short course on both LC-MS and MS-MS, which provided an excellent introduction for newcomers to the field. Throughout the workshop, @ 1983 Elsevicr Science Publishers B.V.
VIII
trt-ndrin analytical chcmisty, vol. 2, n?. 6, 1983
product exhibitions were given by Finnigan MAT, Extranuclear Inc., Hewlett-Packard (including an onerating LC-MS system), Nekag’S.A., and Hositrad B.V. The success of this workshop is a strong indication of the growing
acceptance and impact of LC-MS and MS-MS. The 3rd Workshop*, which *For information concerning the 3rd Workshop LC-MS, contact Prof. Dr R. W. Frei, Free University, Department of Analytical Chemistry, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.
Pollution of the forests SOZ, NOx emissions and acid rain A report of the meeting ‘Wood damage by emissions? (Visible damages, results from research, possible measures)’ held in Zurich, Swltzerland, 29 November, 1982.
The increasingly acid rain which falls in parts of Europe and North America, a result of the industrial emission of SO2 and NOx, is generally regarded as harmful. Just how harmful is only now beginning to be realized. A much better understanding of the ecological interactions which occur in the environment will be required before a comprehensive assessment of the impact of these emissions can be made. It is already known that acid rain results in an increased release of metal ions, many of which are toxic, into the soils and lakes of limedeficient areas. It is also known that aluminium ions, for example, are very toxic to fish; that SOz directly affects several plants and trees; and that hydrocarbon and ozone emissions are harmful to forests. But all of these polluted locations and poisoned species are constituents of a closely knit ecosystem and, while it is relatively straightforward to measure elevated levels and toxic effects of a single pollutant in a particular organism, it is much more difficult to obtain an overall picture. For this, more detailed knowledge of the relationship between soil, water, plants and animals is required. The fact that there is a thirst for such knowledge was endorsed by the good attendance at this meeting, held under the chairmanship of Professor Hans Warner, Director of the Institute of Plant Biology at the University of Zurich. The most recently obtained information on the pollution threat to our forests was presented. 0165.9936/83/%01.00
The close proximity of industry to wooded areas in Europe has meant that the former has a seriously adverse effect on the latter, especially as a result of SO2 bulk streams which result from growing industrial activity and power plants. K.-F. Wentzel (Wiesbaden) stated that the high chimneys currently used to disperse pollutants to an altitude of 1 000-2 000 m have resulted in a pollution effect due to a combination of local sources and more distant sources in many areas. The result has been a rapid increase in damage to forests, especially since frost, ice, storms and infestation by insects and micro-organisms increase the destruction of enfeebled trees. The extent of this damage is clear, with more than 20 000 km2 of forest in the 2 Germanys, Czechoslovakia and Poland now being destroyed annually, 10 times the area destroyed in 1962. The conifer forests, which grow at higher altitudes, are particularly at risk. Globally, about 100 million t of SO2 are emitted per annum. The average atmospheric concentration of this pollutant, for example in Switzerland, is about 10 pg me3 which corresponds to a deposition rate of 13 kg sulphur ha-’ per year. At this level SO2 is not particularly harmful to trees, but instances occur where local SO2 pollution greatly exceeds these concentrations. It is thought that SO2 levels of 25 lug rnw3 or more are harmful to trees. Nonetheless, J. Fuhrer (Berne) asserted that SO2 pollution, at least in Europe, is becoming less of a problem as a result of more stringent emission controls. The continued increase in atmospheric NOX levels is now a matter for greater concern. For example, in Switzerland atmospheric NOX levels of 33 pg rnT3
will be held in 2 years time, again in Montreux (24-26 October, 1984), will certainly confirm this trend. J. A. APFFEL
Ds James A. Abffel is in the Departmtnt of Analytical Chemistry, The Free University, Amsterdam, The Netherlands.
(in rural areas) and 100 pg m-’ (in industrial or urban areas) have been observed. The result has been rain water with a pH of 4.3 - the European acid rain problem is evidently not confined to Scandinavia. Again using Switzerland as an example, G. Leutert (Berne) described the problems acid rain has produced in 57 lakes in only one canton (Tessin). He also maintained that the new international convention on the emission of pollutants, while a landmark in international pollution control, is inadequate, because threshold limits and penal consequences are not covered. In addition, local sources of pollution should be taken into consideration. Leutert asserted that no power station should be built in the future without proper flue gas control (high chimney stacks are no substitute) and that coal and oil for other fuel purposes should be desulphurized prior to use. Traffic is the source of 75% of NOX emissions and legal control of this will be enforced in Switzerland from 1986.
Interactions with soil and water B. Ulrich (Gottingen) provided some figures on the various sources of air pollution in the FRG. These are shown in Table I. In both the air and the soil, sulphuric acid and nitric acid react with alkalis, aluminium ions and heavy metal ions. In lime-rich soils TABLE I. Acid deposition from various sources
in Germany Sot
NOx
Total
Power plants Industry Domestic sources Traffic
2.5 1.2 0.6 0.1
0.8 0.5 0.1 1.2
3.3 1.7 0.7 1.3
Total
4.4
2.6
7.0
Acid equivalent year. 0
units - km01 1983
Hf ha-’ per
Elwvicr Science
Publishera B.V.
trends in aqalytical chmistry, vol. 2, no. 6, 1983
MEETING REPORTS
Interfacial topics A report on the 2nd Workshop on Liquid Chromatography-Mass Spectrometry, held in Montreux, Switzerland, 21-22 October 1982 Two relatively new analytical techniques, liquid chromatography-mass spectrometry (LC-MS) and tandem mass spectrometry (MS-MS), were the focus of interest at the recent 2nd workshop on LC-MS. The workshop was organized by the International Association of Environmental Analytical Chemistry and coordinated by Frei (Amsterdam), Guiochon (Paris) and Nibbering (Amsterdam). The topics covered were the one-line combination of high performance liquid chromatography (HPLC) with mass spectrometry (MS) and the coupling of MS with a second MS analysis. Three lectures gave overviews on the subjects. Fenselau (Johns Hopkins University) covered recent advances in soft ionization techniques for MS. These include chemical ionization, field desorption, laser desorption, Cf-252 plasma desorption, secondary ion MS, fast atom bombardment, electrohydrodynamic ionization, thermospray techniques and solvent evaporation from preformed ions. Guiochon and Arpino (Ecole Polytechnique, Paris) focused on the requirements made by the chromatographic system on the mass spectrometer, such as the need for both qualitative and quantitative information and a fast response time which preserves the chromatographic integrity. Huber (University of Vienna) examined the coupling of two analytical techniques from the view-point of information theory. Huber concluded that more information is obtained by coupling two dissimilar chromatographic separations than by coupling chromatography with MS.
Interfaces In recent years, several interface principles have been developed for coupling HPLC and MS in order to obtain, for non-volatile compounds, the same structural data and selectivity in detection which gas chromatography (GC)-MS provides for more 0165~9936/&/$01.00
volatile analytes. These interface systems were well represented by researchers actively involved in their application and development. Games (Univesity College, CardifI) and others presented recent results with LC-MS using transport systems. These were first introduced commercially by Finnigan and employ a moving wire or belt which carries the LC efIluent into the MS vacuum system through a series of vacuum locks, removing most of the solvent on the way. Advances in this approach include the use of miniaturized liquid chromatography (LC) systems which minimize the need for the removal of large amounts of solvent by IR radiation (which can lead to sample decomposition) and which allow rapid analyses to be performed. A variety of ionization techniques used in conjunction with ‘the belt’, such as chemical ionization, electron impact and fast atom bombardment were also discussed. Benninghoven (University of Miinster) discussed the coupling of belt systems with secondary ion MS (SIMS). This system shows good sensitivity (1 O-l2 mol) as an LC detector but has some problems which result from variation in the sample ionization probability due to the chemical environment, i.e. the mobile phase. A second LC-MS interface system, direct liquid introduction (DLI) was discussed by Henion (Cornell University), Arpino (Ecole Polytechnique, Paris) and others. The DLI probe operates by introducing up to 40 ~1 of liquid directly into the MS ionization source. Advances in these systems include: the use of miniaturized LC in which the total LC effluent can be introduced into the MS, increasing the sensitivity of the technique; the use ofa de-solvation chamber between the DLI probe and the ion source, which serves to enrich the sample with respect to the solvent; and the analysis ofpreformed ions, in which no separate ionization technique is required. A third type of interface was described by Christensen (US National Bureau of Standards) which uses a heated wire, along which the LC
effluent flows while the solvent is evaporated and the sample enriched. The sample is then fed into the MS ion source via an ultrasonic nebulizer which utilizes magnetothe constrictive properties of a nickel wire to produce the necessary ultrasonic vibration. An interface which couples HPLC with an MS system utilizing Cf-252 plasma desorption and a time-of-flight mass-spectrometer was described by Jungclas et al. (Philipps University, Marburg). This interface consists of a disc which rotates to collect effluent fractions from the LC. The fractions thus stored can be rotated into the ionization source and analysed by MS. A similar device was presented by Heresch and Huber (University of Vienna) which uses a small indented rod to collect fractions for laser desorption MS. An interesting panel discussion, organized by Martin (Glaxo Ltd.) compared the use of the DLI and moving belt interfaces in a ‘roundrobin’ analysis of the drug ranitidine and its metabolites. Of the results presented, the analysis using the DLI interface by Dixon (Hewlett-Packard) showed advantages over the other analysis using the belt transport system, particularly for thermally labile metabolites. The subject of MS-MS was addressed by Hunt (University of Virginia), who presented very convincing arguments for the use of triple quadrupole systems in the screening of complex matrices. The triple quadrupole separates individual components as molecular ions in the first quadrupole MS. Fragments (or ‘daughter ions’) are subsequently produced in a second quadrupole mass filter by collision activated disssociation, and these are analysed in a third quadrupole. The screening of all the U.S. Environmental Protection Agency priority pollutants in under 30 min per sample was presented as an example. Several other papers were given on the subject, indicating the growth of interest and application of this new technique. The workshop was preceded by a P-day short course on both LC-MS and MS-MS, which provided an excellent introduction for newcomers to the field. Throughout the workshop, @ 1983 Elsevicr Science Publishers B.V.
VIII
trt-ndrin analytical chcmisty, vol. 2, n?. 6, 1983
product exhibitions were given by Finnigan MAT, Extranuclear Inc., Hewlett-Packard (including an onerating LC-MS system), Nekag’S.A., and Hositrad B.V. The success of this workshop is a strong indication of the growing
acceptance and impact of LC-MS and MS-MS. The 3rd Workshop*, which *For information concerning the 3rd Workshop LC-MS, contact Prof. Dr R. W. Frei, Free University, Department of Analytical Chemistry, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.
Pollution of the forests SOZ, NOx emissions and acid rain A report of the meeting ‘Wood damage by emissions? (Visible damages, results from research, possible measures)’ held in Zurich, Swltzerland, 29 November, 1982.
The increasingly acid rain which falls in parts of Europe and North America, a result of the industrial emission of SO2 and NOx, is generally regarded as harmful. Just how harmful is only now beginning to be realized. A much better understanding of the ecological interactions which occur in the environment will be required before a comprehensive assessment of the impact of these emissions can be made. It is already known that acid rain results in an increased release of metal ions, many of which are toxic, into the soils and lakes of limedeficient areas. It is also known that aluminium ions, for example, are very toxic to fish; that SOz directly affects several plants and trees; and that hydrocarbon and ozone emissions are harmful to forests. But all of these polluted locations and poisoned species are constituents of a closely knit ecosystem and, while it is relatively straightforward to measure elevated levels and toxic effects of a single pollutant in a particular organism, it is much more difficult to obtain an overall picture. For this, more detailed knowledge of the relationship between soil, water, plants and animals is required. The fact that there is a thirst for such knowledge was endorsed by the good attendance at this meeting, held under the chairmanship of Professor Hans Warner, Director of the Institute of Plant Biology at the University of Zurich. The most recently obtained information on the pollution threat to our forests was presented. 0165.9936/83/%01.00
The close proximity of industry to wooded areas in Europe has meant that the former has a seriously adverse effect on the latter, especially as a result of SO2 bulk streams which result from growing industrial activity and power plants. K.-F. Wentzel (Wiesbaden) stated that the high chimneys currently used to disperse pollutants to an altitude of 1 000-2 000 m have resulted in a pollution effect due to a combination of local sources and more distant sources in many areas. The result has been a rapid increase in damage to forests, especially since frost, ice, storms and infestation by insects and micro-organisms increase the destruction of enfeebled trees. The extent of this damage is clear, with more than 20 000 km2 of forest in the 2 Germanys, Czechoslovakia and Poland now being destroyed annually, 10 times the area destroyed in 1962. The conifer forests, which grow at higher altitudes, are particularly at risk. Globally, about 100 million t of SO2 are emitted per annum. The average atmospheric concentration of this pollutant, for example in Switzerland, is about 10 pg me3 which corresponds to a deposition rate of 13 kg sulphur ha-’ per year. At this level SO2 is not particularly harmful to trees, but instances occur where local SO2 pollution greatly exceeds these concentrations. It is thought that SO2 levels of 25 lug rnw3 or more are harmful to trees. Nonetheless, J. Fuhrer (Berne) asserted that SO2 pollution, at least in Europe, is becoming less of a problem as a result of more stringent emission controls. The continued increase in atmospheric NOX levels is now a matter for greater concern. For example, in Switzerland atmospheric NOX levels of 33 pg rnT3
will be held in 2 years time, again in Montreux (24-26 October, 1984), will certainly confirm this trend. J. A. APFFEL
Ds James A. Abffel is in the Departmtnt of Analytical Chemistry, The Free University, Amsterdam, The Netherlands.
(in rural areas) and 100 pg m-’ (in industrial or urban areas) have been observed. The result has been rain water with a pH of 4.3 - the European acid rain problem is evidently not confined to Scandinavia. Again using Switzerland as an example, G. Leutert (Berne) described the problems acid rain has produced in 57 lakes in only one canton (Tessin). He also maintained that the new international convention on the emission of pollutants, while a landmark in international pollution control, is inadequate, because threshold limits and penal consequences are not covered. In addition, local sources of pollution should be taken into consideration. Leutert asserted that no power station should be built in the future without proper flue gas control (high chimney stacks are no substitute) and that coal and oil for other fuel purposes should be desulphurized prior to use. Traffic is the source of 75% of NOX emissions and legal control of this will be enforced in Switzerland from 1986.
Interactions with soil and water B. Ulrich (Gottingen) provided some figures on the various sources of air pollution in the FRG. These are shown in Table I. In both the air and the soil, sulphuric acid and nitric acid react with alkalis, aluminium ions and heavy metal ions. In lime-rich soils TABLE I. Acid deposition from various sources
in Germany Sot
NOx
Total
Power plants Industry Domestic sources Traffic
2.5 1.2 0.6 0.1
0.8 0.5 0.1 1.2
3.3 1.7 0.7 1.3
Total
4.4
2.6
7.0
Acid equivalent year. 0
units - km01 1983
Hf ha-’ per
Elwvicr Science
Publishera B.V.