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Bioavailability of platinum emitted from automobile exhaust
Toxicology Letters 96,97 (1998) 163 – 167
Bioavailability of platinum emitted from automobile exhaust S. Artelt, H. Kock, D. Nachtigall, U. Heinrich * Fraunhofer-Institute of Toxicology and Aerosol Research, Nikolai-Fuchs-Str. 1, 30625 Hano6er, Germany
Abstract A model substance was used which is similar in respect to platinum content of exhaust particles emitted from a three-way-catalytic converter equipped engine. The bioavailability of platinum from such exhaust particles and the kind of platinum species formed in vivo were assessed. An in vitro solubility test showed a solubility of approximately 10 percent of platinum content of the model substance in physiological sodium chloride solution. Two short-term animal studies (8 days) were performed. In all examined rat tissues and body fluids platinum could be detected. In addition, the contribution of the overall bioavailability caused by swallowing a certain amount of the intratracheally applied platinum was evaluated by oral application. It was very low. An analytical method was developed to determine platinum species. Synthetic samples (matrix with a platinum standard solution) were analysed. In rat bronchoalveolar lavage spiked with a platinum standard solution only low molecular complexed platinum was found whereas in rat blood plasma all platinum was bound to proteins. In ongoing studies, the model substance is being tested in a three month rat inhalation study. © 1998 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Platinum in automobile exhaust; Bioavailability of platinum; Particle effects; Platinum speciation
1. Introduction Automobile catalytic converters reduce air pollution to an extent of 90 percent by converting carbon monoxide, nitrogen oxides and hydrocarbons to less toxic compounds. Under operating conditions there is an abrasion of catalytic material, e.g. platinum, which is released in the exhaust. The possible human risk of exposure to platinum in the exhaust is still under discussion. Platinum concentrations in the environment have
* Corresponding author.
increased remarkably in the last years. The earth’s crust contains approximately 5 mg/kg platinum (Hartley, 1991). Up to 130 mg/kg platinum were detected in dust from air samples collected in Germany (Alt et al., 1993). Dust in an automobile tunnel in Austria contained 60 mg/kg platinum (Schramel and Lustig, 1997). Platinum concentrations in soil near German highways ranged from 1 to 72 mg/kg decreasing with distance from the highway (Zereini et al., 1997). In sewage sludge increasing platinum concentrations were found from 1972 to 1992 (Helmers et al., 1994). Platinum (0.2 mg/l) was found in samples of drinking water in England (Wildner, 1996).
0378-4274/98/$19.00 © 1998 Elsevier Science Ireland Ltd. All rights reserved. PII S0378-4274(98)00064-2
S. Artelt et al. / Toxicology Letters 96,97 (1998) 163–167
164
The magnitude of platinum emission from commonly used three-way-catalytic converters tested under laboratory conditions was measured on a computer controlled dynamometer (Ko¨nig et al., 1992). The aerosol fraction of the exhaust (B 5 mm) contained platinum metal which was attached to aluminium oxide particles (Loose and Schlo¨gl, 1996). An analysis procedure consisting of sampling, sample preparation (digestion), and quantification by inductively coupled plasma mass spectrometry was developed and validated to determine ng/m3 levels of platinum. To assess the effects of platinum on humans, the bioavailability of such exhaust particles and the kind of platinum species found in vivo has to be determined. Exhaust particles themselves are not very suitable for the proposed experiments for several reasons: 1. the particle emission is extremely low so that the collecting time would be too long; 2. the exhaust particles contain not only platinum but also various other products, e.g. soot, inorganic salts, other metals, and organic substances which may themselves induce toxicity making it difficult to evaluate the effect of platinum itself. Thus, a model substance was designed to simulate the platinum component
of genuine exhaust particles, and further to be in the size range of the inhalable fraction for rats.
2. Materials and methods
2.1. Model substance The model substance consisted of platinum (0) particles attached to aluminium oxide particles (Siralox® 5/320, Degussa, Hanau, Germany). The platinum particle sizes were in the order of nanometers, the aluminium particles having maximum diameters of 5 mm. The platinum content of the model substance was 30.1 mg platinum per g substance. The particles were of a high catalytic activity similar to the platinum in engine exhaust (Ru¨hle et al., 1997).
2.2. In 6itro solubility test The model substance was treated with ultrasound for 10 min in a 0.9% sodium chloride solution (physiological conditions), allowed to react for half an hour, and the suspension was filtered through a membrane filter (Minisart® 0.2
Table 1 Platinum content in rat tissues, blood and lung macrophages 8 days after intratracheal instillation of 10 and 2 mg model substance (means of four animals with standard deviation given) 10 mg model substance (mg/total tissue) Lung Lung macrophages Kidney (both) Liver Spleen Stomach Adrenal gland (both) Blood
1
2 mg model substance (mg/g wet weight)
347 922
2139 30
1
1
5.7 9 0.29 1.4 9 0.13 0.22 9 0.032 0.10 9 0.011 0.0039 9 0.00059 1.8 9 0.37 mg/total blood content2
4.7 9 0.086 0.21 90.037 0.51 90.088 0.09890.0058 0.091 9 0.0071 0.1390.028 mg/ml
(mg/total tissue) 31 9 5 25 9 5 mg/total amount of cells 0.68 90.092 0.22 9 0.082 0.033 9 0.0075 0.012 9 0.0022 B0.00072 0.30 90.054 mg/total blood content
(mg/g wet weight) 319 5 3.9 90.75 mg/1 Mio cells 0.51 90.054 0.031 90.011 0.074 90.015 0.011 90.0019 B0.016 0.021 90.0043 mg/ml
Lung lavage failed, no lung macrophages were taken. Total blood; platinum content referred to the total blood content; the total blood content was calculated by 7% of the rat body weight. 2
S. Artelt et al. / Toxicology Letters 96,97 (1998) 163–167
165
Table 2 Platinum concentration in faeces and urine of rats of 8 days, after oral application of 33 mg model substance (mean of four animals with standard deviation given) (mg/24 h faeces or 24 h urine) Day 1
Day 2
Day 3
Day 4
Faeces Urine
944 953 0.85 9 0.20
1159 84 0.0729 0.044
32 9 15 0.060 90.019
1.8 9 1.5 0.018 9 0.0086
Faeces Urine
Day 5 0.72 9 0.29 0.031 9 0.0068
Day 6 0.29 9 0.18 0.0169 0.0030
Day 7 0.24 9 0.14 0.019 90.0046
Day 8 0.22 9 0.17 0.013 9 0.0047
mm, Sartorius, Go¨ttingen, Germany). The dissolved platinum content was determined by inductively coupled plasma mass spectrometry (PlasmaQuad 2+, VG-Elemental, Offenbach, Germany) (Nachtigall et al., 1996).
2.3. Study design (A) 10 week old female Lewis rats (LEW/CrlBR, Charles River, Sulzfeld, Germany), eight rats per group, were taken for the 8-day animal studies. Single doses of 0, 2 mg and 10 mg respectively of the model substance in 0.3 ml of 0.9% sodium chloride solution were administered by intratracheal instillation to three groups. After 8 days the rats were sacrified and the platinum content in lung, liver, spleen, kidney, adrenal gland, stomach, and blood was determined. The lung macrophages were taken by massage of the lung and lavage with saline (six times with 5 ml). Parallel to this, single doses of 0 and 33 mg of the model substance in 1 ml of 0.9% sodium chloride solution was given by lavage. The oral study was included to investigate the effect of the small amount of platinum of the model substance which might have been swallowed during intratracheal installation. Platinum was determined in lung, liver, spleen, kidney, adrenal gland, stomach, stomach content, intestine, intestine content, and blood. Samples of urine and faeces were taken daily for platinum analysis. (B) The analytical matrices bronchoalveolar lavage and blood were taken from a further group of control rats for the development of an analytical
method to determine platinum species. The platinum species can be divided into ‘soluble protein bound platinum‘‘ and ‘‘soluble low molecular complexed platinum’. Gel permeation chromatography was used for isolation of macromolecular protein bound platinum (HiTrap Desalting Column, Sephadex G-25 Superfine (1.6× 2.5 cm), flow rate 1–10 ml/min, PBS buffer, UV-detection, Pharmacia Biotech, Uppsala, Sweden). The low molecular proteins were separated by ion chromatography (DX 500 system, Dionex Corporation, Sunnyvale, CA). The total platinum content in collected fractions was determined by inductively coupled plasma mass spectrometry (PlasmaQuad 2+ , VG-Elemental) (Nachtigall, 1997). 3. Results and discussion An in vitro solubility test was developed to determine the solubility of the platinum model
Fig. 1. Platinum in rat broncho-alveolar-lavage (BAL)
166
S. Artelt et al. / Toxicology Letters 96,97 (1998) 163–167
first peak (after 2.5 min) is protein bound platinum and the following peaks (later than 4.5 min) can be ascribed to soluble low molecular platinum complexes. In the bronchoalveolar lavage only low molecular complexed platinum was found; no platinum is protein bound. In blood plasma only protein bound platinum was observed. Further studies are in progress to determine the platinum bioavailability in an inhalation study with rats over a period of three months.
Acknowledgements Fig. 2. Protein-bound platinum in rat blood plasma
particles. The model substance (containing platinum (0)) showed a solubility of 10% w/w in physiological sodium chloride solution. The bioavailability of the model substance in vivo was determined by administering it as a single dose by intratracheal instillation or orally to rats and following the fate of the model substance over 8 days. In the study using intratracheal instillation, maximum platinum concentrations were found in the lung and the lung macrophages due to the application. Smaller amounts of platinum were detected in blood, kidney, and liver showing the bioavailability of platinum particles of the model substance (Table 1). In parallel, platinum was administered to the rats by oral application. After 8 days the platinum content in rat tissues including the gastrointestinal tract was determined. 97% of the platinum in faeces and 85% of the platinum in urine (where 100% is total platinum content in faeces and urine over 8 days) was excreted during the first two days (Table 2). Small amounts of platinum were detected in the stomach content and in the kidney, but not in liver, stomach, intestine and intestine content. Thus, the contribution of the small amount of platinum which might have been swallowed during intratracheal application would not alter the bioavailable fraction of intratracheal administered platinum to a great extent. Figs. 1 and 2 show the gel chromatograms of the platinum species of the synthetic samples from the development of the analytical method. The
Design of the model substance by Professor Dr R. Schlo¨gl and his group at the Fritz–Haber-Institut of the Max–Planck-Gesellschaft in Berlin.This work has been part of a scientific program entitled ‘Emissions of precious metals’, which has been financially supported by the German Federal Ministry of Education, Science, Research and Technology (BMBF).
References Alt, F., Bambauer, A., Hoppstock, K., Mergler, B., To¨lg, G., 1993. Platinum traces in airborne particulate matter. Determination of whole content, particle size distribution and soluble platinum. Fresenius J. Anal. Chem. 346, 693 – 696. Hartley, R., 1991. Chemistry of the platinum group metals. Elsevier, Amsterdam. Helmers, E., Mergel, N., Barchet, R., 1994. Platin in Kla¨rschlammasche und an Gra¨sern. UWSF-Z. Umweltchem. O8 kotox 6 (3), 130 – 134. Ko¨nig, H.P., Hertel, R.F., Koch, W., Rosner, G., 1992. Determination of platinum emissions from a three-way catalystequipped gasoline engine. Atmos. Environ. 26A (5), 741 – 745. Loose, G., Schlo¨gl, R. (1996) Die chemische Struktur von Platinemissionen aus Dreiwegekatalysatoren, Untersuchung von Partikelemissionen von Platin aus Automobilkatalysatoren mit Photoelektronenspektroskopie, Abschlußbericht zum Verbundvorhaben Edelmetallemissionen. Fo¨rderkennzeichen: 07VPT08A. Nachtigall, D., Kock, H., Artelt, S., et al., 1996. Platinum solubility of a substance designed as a model for emissions of automobile catalytic converters. Fresenius J. Anal. Chem. 354, 742 – 746. Nachtigall, D., 1997. Verfahren zur Bestimmung von Platinspezies in Anorganischen und Biologischen Systemen. Cuvillier Verlag, Go¨ttingen.
S. Artelt et al. / Toxicology Letters 96,97 (1998) 163–167 Ru¨hle, T., Schneider, H., Find, J., Herein, D., Pfa¨nder, N., Wild, U., Schlo¨gl, R., Nachtigall, D., Artelt, S., Heinrich, U., 1997. Preparation and characterization of Pt/Al2O3 aerosol precursors as model Pt-emissions from catalytic converters. Appl. Catal. B 14, 69–84. Schramel, P., Lustig, S., 1997. Imissions-Situation fu¨r Platin (Vorkommen von Platin in Luft, Boden, Wasser, Futtermittel, Lebensmittel). Herausgeber: GSF-Forschungszentrum fu¨r Umwelt und Gesundheit GmbH; Projekttra¨ger des BMBF fu¨r ‘Umwelt und Klimaforschung’, Ku¨hbachstr. 11, D-81543 Mu¨nchen, 57.
167
Wildner, H., 1996. Kalibration, Probenzufuhr und Detektion fu¨r die Platinbestimmung im sub pg/g-Bereich. Proceedings 3. Platin-Anwendertreffen, 14.-15. Oktober 1996, Herausgeber: Lustig, S., Schramel, PGSF-Forschungszentrum/Institut fu¨r O8 kologische Chemie, Mu¨nchen. Zereini, F., Alt, F., Rankenburg, K., Beyer, J.-M., Artelt, S., 1997. Verteilung von Platingruppenelementen (PGE) in den Umweltkompartimenten Boden, Schlamm, Straßenstaub, Straßenkehrgut und Wasser. Emission von Platingruppenelementen aus Kfz-Abgaskatalysatoren. UWSF-Z. Umweltchem. O8 kotox 9 (4), 193 – 200.
.
Bioavailability of platinum emitted from automobile exhaust S. Artelt, H. Kock, D. Nachtigall, U. Heinrich * Fraunhofer-Institute of Toxicology and Aerosol Research, Nikolai-Fuchs-Str. 1, 30625 Hano6er, Germany
Abstract A model substance was used which is similar in respect to platinum content of exhaust particles emitted from a three-way-catalytic converter equipped engine. The bioavailability of platinum from such exhaust particles and the kind of platinum species formed in vivo were assessed. An in vitro solubility test showed a solubility of approximately 10 percent of platinum content of the model substance in physiological sodium chloride solution. Two short-term animal studies (8 days) were performed. In all examined rat tissues and body fluids platinum could be detected. In addition, the contribution of the overall bioavailability caused by swallowing a certain amount of the intratracheally applied platinum was evaluated by oral application. It was very low. An analytical method was developed to determine platinum species. Synthetic samples (matrix with a platinum standard solution) were analysed. In rat bronchoalveolar lavage spiked with a platinum standard solution only low molecular complexed platinum was found whereas in rat blood plasma all platinum was bound to proteins. In ongoing studies, the model substance is being tested in a three month rat inhalation study. © 1998 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Platinum in automobile exhaust; Bioavailability of platinum; Particle effects; Platinum speciation
1. Introduction Automobile catalytic converters reduce air pollution to an extent of 90 percent by converting carbon monoxide, nitrogen oxides and hydrocarbons to less toxic compounds. Under operating conditions there is an abrasion of catalytic material, e.g. platinum, which is released in the exhaust. The possible human risk of exposure to platinum in the exhaust is still under discussion. Platinum concentrations in the environment have
* Corresponding author.
increased remarkably in the last years. The earth’s crust contains approximately 5 mg/kg platinum (Hartley, 1991). Up to 130 mg/kg platinum were detected in dust from air samples collected in Germany (Alt et al., 1993). Dust in an automobile tunnel in Austria contained 60 mg/kg platinum (Schramel and Lustig, 1997). Platinum concentrations in soil near German highways ranged from 1 to 72 mg/kg decreasing with distance from the highway (Zereini et al., 1997). In sewage sludge increasing platinum concentrations were found from 1972 to 1992 (Helmers et al., 1994). Platinum (0.2 mg/l) was found in samples of drinking water in England (Wildner, 1996).
0378-4274/98/$19.00 © 1998 Elsevier Science Ireland Ltd. All rights reserved. PII S0378-4274(98)00064-2
S. Artelt et al. / Toxicology Letters 96,97 (1998) 163–167
164
The magnitude of platinum emission from commonly used three-way-catalytic converters tested under laboratory conditions was measured on a computer controlled dynamometer (Ko¨nig et al., 1992). The aerosol fraction of the exhaust (B 5 mm) contained platinum metal which was attached to aluminium oxide particles (Loose and Schlo¨gl, 1996). An analysis procedure consisting of sampling, sample preparation (digestion), and quantification by inductively coupled plasma mass spectrometry was developed and validated to determine ng/m3 levels of platinum. To assess the effects of platinum on humans, the bioavailability of such exhaust particles and the kind of platinum species found in vivo has to be determined. Exhaust particles themselves are not very suitable for the proposed experiments for several reasons: 1. the particle emission is extremely low so that the collecting time would be too long; 2. the exhaust particles contain not only platinum but also various other products, e.g. soot, inorganic salts, other metals, and organic substances which may themselves induce toxicity making it difficult to evaluate the effect of platinum itself. Thus, a model substance was designed to simulate the platinum component
of genuine exhaust particles, and further to be in the size range of the inhalable fraction for rats.
2. Materials and methods
2.1. Model substance The model substance consisted of platinum (0) particles attached to aluminium oxide particles (Siralox® 5/320, Degussa, Hanau, Germany). The platinum particle sizes were in the order of nanometers, the aluminium particles having maximum diameters of 5 mm. The platinum content of the model substance was 30.1 mg platinum per g substance. The particles were of a high catalytic activity similar to the platinum in engine exhaust (Ru¨hle et al., 1997).
2.2. In 6itro solubility test The model substance was treated with ultrasound for 10 min in a 0.9% sodium chloride solution (physiological conditions), allowed to react for half an hour, and the suspension was filtered through a membrane filter (Minisart® 0.2
Table 1 Platinum content in rat tissues, blood and lung macrophages 8 days after intratracheal instillation of 10 and 2 mg model substance (means of four animals with standard deviation given) 10 mg model substance (mg/total tissue) Lung Lung macrophages Kidney (both) Liver Spleen Stomach Adrenal gland (both) Blood
1
2 mg model substance (mg/g wet weight)
347 922
2139 30
1
1
5.7 9 0.29 1.4 9 0.13 0.22 9 0.032 0.10 9 0.011 0.0039 9 0.00059 1.8 9 0.37 mg/total blood content2
4.7 9 0.086 0.21 90.037 0.51 90.088 0.09890.0058 0.091 9 0.0071 0.1390.028 mg/ml
(mg/total tissue) 31 9 5 25 9 5 mg/total amount of cells 0.68 90.092 0.22 9 0.082 0.033 9 0.0075 0.012 9 0.0022 B0.00072 0.30 90.054 mg/total blood content
(mg/g wet weight) 319 5 3.9 90.75 mg/1 Mio cells 0.51 90.054 0.031 90.011 0.074 90.015 0.011 90.0019 B0.016 0.021 90.0043 mg/ml
Lung lavage failed, no lung macrophages were taken. Total blood; platinum content referred to the total blood content; the total blood content was calculated by 7% of the rat body weight. 2
S. Artelt et al. / Toxicology Letters 96,97 (1998) 163–167
165
Table 2 Platinum concentration in faeces and urine of rats of 8 days, after oral application of 33 mg model substance (mean of four animals with standard deviation given) (mg/24 h faeces or 24 h urine) Day 1
Day 2
Day 3
Day 4
Faeces Urine
944 953 0.85 9 0.20
1159 84 0.0729 0.044
32 9 15 0.060 90.019
1.8 9 1.5 0.018 9 0.0086
Faeces Urine
Day 5 0.72 9 0.29 0.031 9 0.0068
Day 6 0.29 9 0.18 0.0169 0.0030
Day 7 0.24 9 0.14 0.019 90.0046
Day 8 0.22 9 0.17 0.013 9 0.0047
mm, Sartorius, Go¨ttingen, Germany). The dissolved platinum content was determined by inductively coupled plasma mass spectrometry (PlasmaQuad 2+, VG-Elemental, Offenbach, Germany) (Nachtigall et al., 1996).
2.3. Study design (A) 10 week old female Lewis rats (LEW/CrlBR, Charles River, Sulzfeld, Germany), eight rats per group, were taken for the 8-day animal studies. Single doses of 0, 2 mg and 10 mg respectively of the model substance in 0.3 ml of 0.9% sodium chloride solution were administered by intratracheal instillation to three groups. After 8 days the rats were sacrified and the platinum content in lung, liver, spleen, kidney, adrenal gland, stomach, and blood was determined. The lung macrophages were taken by massage of the lung and lavage with saline (six times with 5 ml). Parallel to this, single doses of 0 and 33 mg of the model substance in 1 ml of 0.9% sodium chloride solution was given by lavage. The oral study was included to investigate the effect of the small amount of platinum of the model substance which might have been swallowed during intratracheal installation. Platinum was determined in lung, liver, spleen, kidney, adrenal gland, stomach, stomach content, intestine, intestine content, and blood. Samples of urine and faeces were taken daily for platinum analysis. (B) The analytical matrices bronchoalveolar lavage and blood were taken from a further group of control rats for the development of an analytical
method to determine platinum species. The platinum species can be divided into ‘soluble protein bound platinum‘‘ and ‘‘soluble low molecular complexed platinum’. Gel permeation chromatography was used for isolation of macromolecular protein bound platinum (HiTrap Desalting Column, Sephadex G-25 Superfine (1.6× 2.5 cm), flow rate 1–10 ml/min, PBS buffer, UV-detection, Pharmacia Biotech, Uppsala, Sweden). The low molecular proteins were separated by ion chromatography (DX 500 system, Dionex Corporation, Sunnyvale, CA). The total platinum content in collected fractions was determined by inductively coupled plasma mass spectrometry (PlasmaQuad 2+ , VG-Elemental) (Nachtigall, 1997). 3. Results and discussion An in vitro solubility test was developed to determine the solubility of the platinum model
Fig. 1. Platinum in rat broncho-alveolar-lavage (BAL)
166
S. Artelt et al. / Toxicology Letters 96,97 (1998) 163–167
first peak (after 2.5 min) is protein bound platinum and the following peaks (later than 4.5 min) can be ascribed to soluble low molecular platinum complexes. In the bronchoalveolar lavage only low molecular complexed platinum was found; no platinum is protein bound. In blood plasma only protein bound platinum was observed. Further studies are in progress to determine the platinum bioavailability in an inhalation study with rats over a period of three months.
Acknowledgements Fig. 2. Protein-bound platinum in rat blood plasma
particles. The model substance (containing platinum (0)) showed a solubility of 10% w/w in physiological sodium chloride solution. The bioavailability of the model substance in vivo was determined by administering it as a single dose by intratracheal instillation or orally to rats and following the fate of the model substance over 8 days. In the study using intratracheal instillation, maximum platinum concentrations were found in the lung and the lung macrophages due to the application. Smaller amounts of platinum were detected in blood, kidney, and liver showing the bioavailability of platinum particles of the model substance (Table 1). In parallel, platinum was administered to the rats by oral application. After 8 days the platinum content in rat tissues including the gastrointestinal tract was determined. 97% of the platinum in faeces and 85% of the platinum in urine (where 100% is total platinum content in faeces and urine over 8 days) was excreted during the first two days (Table 2). Small amounts of platinum were detected in the stomach content and in the kidney, but not in liver, stomach, intestine and intestine content. Thus, the contribution of the small amount of platinum which might have been swallowed during intratracheal application would not alter the bioavailable fraction of intratracheal administered platinum to a great extent. Figs. 1 and 2 show the gel chromatograms of the platinum species of the synthetic samples from the development of the analytical method. The
Design of the model substance by Professor Dr R. Schlo¨gl and his group at the Fritz–Haber-Institut of the Max–Planck-Gesellschaft in Berlin.This work has been part of a scientific program entitled ‘Emissions of precious metals’, which has been financially supported by the German Federal Ministry of Education, Science, Research and Technology (BMBF).
References Alt, F., Bambauer, A., Hoppstock, K., Mergler, B., To¨lg, G., 1993. Platinum traces in airborne particulate matter. Determination of whole content, particle size distribution and soluble platinum. Fresenius J. Anal. Chem. 346, 693 – 696. Hartley, R., 1991. Chemistry of the platinum group metals. Elsevier, Amsterdam. Helmers, E., Mergel, N., Barchet, R., 1994. Platin in Kla¨rschlammasche und an Gra¨sern. UWSF-Z. Umweltchem. O8 kotox 6 (3), 130 – 134. Ko¨nig, H.P., Hertel, R.F., Koch, W., Rosner, G., 1992. Determination of platinum emissions from a three-way catalystequipped gasoline engine. Atmos. Environ. 26A (5), 741 – 745. Loose, G., Schlo¨gl, R. (1996) Die chemische Struktur von Platinemissionen aus Dreiwegekatalysatoren, Untersuchung von Partikelemissionen von Platin aus Automobilkatalysatoren mit Photoelektronenspektroskopie, Abschlußbericht zum Verbundvorhaben Edelmetallemissionen. Fo¨rderkennzeichen: 07VPT08A. Nachtigall, D., Kock, H., Artelt, S., et al., 1996. Platinum solubility of a substance designed as a model for emissions of automobile catalytic converters. Fresenius J. Anal. Chem. 354, 742 – 746. Nachtigall, D., 1997. Verfahren zur Bestimmung von Platinspezies in Anorganischen und Biologischen Systemen. Cuvillier Verlag, Go¨ttingen.
S. Artelt et al. / Toxicology Letters 96,97 (1998) 163–167 Ru¨hle, T., Schneider, H., Find, J., Herein, D., Pfa¨nder, N., Wild, U., Schlo¨gl, R., Nachtigall, D., Artelt, S., Heinrich, U., 1997. Preparation and characterization of Pt/Al2O3 aerosol precursors as model Pt-emissions from catalytic converters. Appl. Catal. B 14, 69–84. Schramel, P., Lustig, S., 1997. Imissions-Situation fu¨r Platin (Vorkommen von Platin in Luft, Boden, Wasser, Futtermittel, Lebensmittel). Herausgeber: GSF-Forschungszentrum fu¨r Umwelt und Gesundheit GmbH; Projekttra¨ger des BMBF fu¨r ‘Umwelt und Klimaforschung’, Ku¨hbachstr. 11, D-81543 Mu¨nchen, 57.
167
Wildner, H., 1996. Kalibration, Probenzufuhr und Detektion fu¨r die Platinbestimmung im sub pg/g-Bereich. Proceedings 3. Platin-Anwendertreffen, 14.-15. Oktober 1996, Herausgeber: Lustig, S., Schramel, PGSF-Forschungszentrum/Institut fu¨r O8 kologische Chemie, Mu¨nchen. Zereini, F., Alt, F., Rankenburg, K., Beyer, J.-M., Artelt, S., 1997. Verteilung von Platingruppenelementen (PGE) in den Umweltkompartimenten Boden, Schlamm, Straßenstaub, Straßenkehrgut und Wasser. Emission von Platingruppenelementen aus Kfz-Abgaskatalysatoren. UWSF-Z. Umweltchem. O8 kotox 9 (4), 193 – 200.
.