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Parallel on-line detection of a methylbismuth species by hyphenated GC/EI-MS/ICP-MS technique as evidence for bismuth methylation by human hepatic cells

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Methylation of metal(loid)s by bacteria or even mammals is a well known process that can lead to increased toxicity for humans. Nevertheless, reliable analytical techniques and tools are indispensable in speciation analysis of trace elements, especially since environmental or biological samples are usually characterised by complex matrices. Here the methylating capability of hepatic cells was observed in vitro. HepG2 cells were incubated with colloidal bismuth subcitrate, bismuth cysteine and bismuth glutathione, respectively for a period of 24 h. For identification the cell lysate was ethylated by sodium tetraethyl borate under neutral conditions. After cryo focussing by purge and trap, the bismuth speciation was carried out via GC/EI-MS/ICP-MS. Colloidal bismuth subcitrate and bismuth cysteine were methylated by HepG2 cells, while no methylated bismuth species was detected after incubation with bismuth glutathione.
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ISSN 1756-5901
Metallomics
Integrated biometal science
1756-5901(2010)2:1;1-B
HOT ARTICLE
Hollmann et al.
Detection of methylbismuth species
by GC/EI-MS/ICP-MS as evidence for
bismuth methylation in hepatic cells
TUTORIAL REVIEW
Bertini and Cavallaro
Bioinformatics in bioinorganic
chemistry
Volume 2 | Number 1 | 2010 Metallomics
Pages 1–92
www.rsc.org/metallomics Volume 2 | Number 1 | January 2010 | Pages 1–92
Parallel on-line detection of a methylbismuth species by hyphenated
GC/EI-MS/ICP-MS technique as evidence for bismuth methylation
by human hepatic cellsw
Markus Hollmann,*
a
Jens Boertz,z
a
Elke Dopp,
b
Joerg Hippler
a
and
Alfred Vitalis Hirner
a
Received 22nd June 2009, Accepted 16th September 2009
First published as an Advance Article on the web 6th October 2009
DOI: 10.1039/b911945k
Methylation of metal(loid)s by bacteria or even mammals is a well known process that can lead
to increased toxicity for humans. Nevertheless, reliable analytical techniques and tools are
indispensable in speciation analysis of trace elements, especially since environmental or biological
samples are usually characterised by complex matrices. Here the methylating capability of hepatic
cells was observed in vitro. HepG2 cells were incubated with colloidal bismuth subcitrate, bismuth
cysteine and bismuth glutathione, respectively for a period of 24 h. For identification the cell
lysate was ethylated by sodium tetraethyl borate under neutral conditions. After cryo focussing by
purge and trap, the bismuth speciation was carried out via GC/EI-MS/ICP-MS. Colloidal
bismuth subcitrate and bismuth cysteine were methylated by HepG2 cells, while no methylated
bismuth species was detected after incubation with bismuth glutathione.
1. Introduction
Inorganic bismuth compounds are known to show low
toxicity,
1
so bismuth is commonly used as a lead substitute,
e.g. in paintings or alloys.
2
Furthermore, it has been used in
medicine for many decades as an anti-gastritic and anti-ulcer
agent.
3
In contrast, organic bismuth compounds like the
permethylated trimethylbismuth (TMBi) may cause encephalo-
pathic symptoms
4
and are proven to be highly toxic as shown
in experiments with cats and dogs.
5
After application of
inorganic bismuth compounds many cases of bismuth poisoning
are well documented, e.g. epidemic-like encephalopathic
diseases in France and Australia.
6,7
It is commonly assumed
that the observed symptoms were caused by conversion of
inorganic bismuth to TMBi.
8
This can be caused by intestinal
microbes as shown by Michalke et al.
8,9
Boertz et al.
determinated TMBi in the human body after ingestion of
colloidal bismuth subcitrate.
10
Von Recklinghausen et al.
observed the uptake of bismuth glutathione and bismuth citrate
by human erythrocytes, lymphocytes and hepatocytes.
11
The
authors assumed that biomethylation of inorganic bismuth
compounds occurs in the human intestinum, however, the
methylation of bismuth in the liver is also imaginable. As
Styblo et al. have shown for arsenic, the lighter homologue of
bismuth, hepatomic cells (HepG2) can methylate inorganic
arsenic.
12
It is already known that heavy metals in living organisms
form complexes with sulfur containing molecules like cysteine
and glutathione.
13,14
Especially the formation of methylmercury
cysteine in fish
15
as a biologically active substance indicates the
importance of small ‘‘biomolecules’’ for transport processes in
animals. The formation of bismuth cysteine and bismuth
glutathione complexes is also possible as shown by Burford
and co-workers.
16,17
Since alkylated bismuth compounds tend to decompose in
water, the importance of bismuth cysteine complexes in the
field of bismuth methylation is emphasized by a study proving
the existence of methylbismuth cysteine in aqueous solution.
18
Speciation analysis of bismuth compounds is usually carried
out by liquid chromatography coupled to mass spectrometry
17
as well as LT-GC/ICP-MS.
10,19–22
For quantification of
bismuth in alloys, stable volatile ethyl derivatives are used
for quantitative determination of bismuth by ICP-AES.
23
The
very same technique has been used for volatilization and
determination of methylated bismuth species in human blood
samples after ingestion of bismuth(
III) citrate–hydroxide
complex.
24
In the present qualitative study, the transformation of
inorganic bismuth to methylated bismuth species by human
hepatic cells (HepG2) is investigated by derivatization of these
species with sodium tetraethyl borate. Then the volatile
bismuth species are detected simultaneously by EI-MS and
ICP-MS after gas chromatographic separation, revealing all
bismuth containing compounds directly through correlation
of both detector signals. This unique analytical system has
a
Institute of Environmental Analytical Chemistry, University of
Duisburg-Essen, Universitaetsstrasse 3-5, 45141 Essen, Germany.
E-mail: markus_hollmann@uni-due.de; Fax: +49 (0)201 1833951;
Tel: +49 (0)201 1833238
b
Institute of Hygiene and Occupational Medicine, University of
Duisburg-Essen, Hufelandstrasse 55, 45122 Essen, Germany.
E-mail: elke.dopp@uni-due.de; Fax: +49 (0)201 7234546;
Tel: + 49( 0)201 7234578
w Electronic supplementary information (ESI) available: Fig. S1–S5,
EI-MS spectra. See DOI: 10.1039/b911945k
z New correspondence address: European Commission, Joint
Research Centre, Institute for Reference Materials and Measurements
(IRMM), Reference Materials Unit, Retieseweg 111, B-2440 Geel,
Belgium. Fax: +32 (0)14571548; Tel: +49 (0)14573005; E-mail:
jens.boertz@uni-due.de
52 | Metallomics, 2010, 2, 52–56 This journal is
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The Royal Society of Chemistry 2010
PAPER www.rsc.org/metallomics | Metallomics
recently proven its usefulness in the determination of volatile
arsenic species generated by the (intestinal) microflora in
human feaces.
25
2. Experimental
2.1 Reagents and standards
All reagents used were of analytical grade or better and are
either purchased from Sigma Aldrich (Buchs, Switzerland)
or from Alfa Aesar (Karlsruhe, Germany). Milli-Q water
(Millipore, Milford, MA, USA) was used for the preparation
of bismuth glutathione and bismuth cysteine. Colloidal bismuth
subcitrate (CBS) was prepared according to Asato et al.
26
The
bismuth complexes of glutathione and cysteine were prepared
according to Burford et al.
17
In brief: bismuth cysteine
and bismuth glutathione were synthesized by adding solid
bismuth(
III) chloride (BiCl
3
) to a saturated solution of
L-cysteine or glutathione, in ultra-pure water in a molar bismuth
to ligand ratio of 2 : 1. The mixture was stirred at room
temperature (20 1C) under an ultra pure argon atmosphere.
In a further step we isolated both complexes by adding small
amounts of methanol until precipitation of a (slightly) yellow
solid occurred. For isolation the crystalline product was
subsequently filtered through a fibreglass filter. Finally the
solid was dried in a vacuum desiccator containing silica gel for
several days.
Colloidal bismuth subcitrate was prepared as follows: to a
solution of bismuth citrate in aqueous ammonia (25%) and
Dulbecco’s phosphate buffered saline (D-PBS, Gibco
s
,
Invitrogent, Karlsruhe, Germany) hydrochloric acid (37%, p.a.,
Riedel-de-Hae
¨
n, Seelze, Germany) was added dropwise until a
pH value of 8.5 was reached. The resulting CBS-suspension
was used without further treatment and characterization.
The solution of each bismuth compound was prepared
separately by dissolving CBS, bismuth cysteine or bismuth
glutathione in D-PBS yielding a solution of 2000 mg bismuth
compound per kg.
2.2 Instrumentation
The 6890 N gas chromatographic system (Agilent Technologies,
Waldbronn, Germany) was equipped with a UNIS 2000 inlet
system (Joint Analytical Systems, Moers, Germany) for
programmed temperature vaporisation (PTV) after purge
and trap sampling.
Two detection systems were used simultaneously: a 5973 N
EI-MS (Agilent Technologies, Waldbronn, Germany), which
served as a molecule selective detector for species conformation,
and a 7500a ICP-MS (Agilent Technologies) for sensitive
and element selective detection of the analytes. Working
parameters for all instruments are listed in Table 1.
More details of this unique system are described elsewhere.
27
2.3 Chromatographic and analytical conditions
To analyze alkylated bismuth species, constant flow separation
was employed on a DB-5 MS capillary column (30 m 250 mm
25 mm, J&W Scientific, Agilent Technologies, Waldbronn,
Germany). The mobile phase was helium (5.0, Air Liquide,
Duesseldorf, Germany). Internal standardization of ICP-MS
was done by continuously adding a solution of 10 ng/ml
thallium.
2.4 Cell culture
Tumorigenic human hepatocellular carcinoma cells (HepG2,
HB 8065, ATCC, USA) were cultured in minimal essential
medium (MEM, CC-Pro, Neustadt, Germany) with Earle’
BSS and sodium bicarbonate (CC-Pro) supplemented with
10% heat-inactivated foetal calf serum (FCS, Gibco
s
,
Invitrogent, Karlsruhe, Germany), nonessential amino acids
(MEM-NEAM, 0.1 mM), sodium pyruvate (1 mM), and
gentamycin (10 mg/mL, all reagents from CC-Pro) at 37 1C
under 5% CO
2
(99.7%, Air Liquide, Duesseldorf, Germany)
and 95% air in a water-jacket incubator (Thermo Forma,
Ohio, USA). HepG2 is an adherent cell line that grows as a
monolayer.
2.5 Incubation of cells
In a 25 cm
2
cell culture flask 10
6
HepG2 cells were cultivated in
5 ml Minimum Essential Medium (MEM) for 24 h. Following
substitution of the medium with 10 ml HEPES and evaluation
of the cell viability via light microscopy the cells were exposed
to 1 ml of each solution containing either CBS, bismuth
cysteine or bismuth gluthathione for 24 h at 37 1C. The final
Bi concentrations for incubation were 105 mg/kg (CBS),
93 mg/kg (BiCys
2
) and 122 mg/kg (BiGSH
2
), respectively.
Cell culture flasks were closed with gas tight caps and Teflon
tape. A butyl-rubber septum was glued on the gas tight cap to
avoid the loss of volatile compounds during sample transfer.
2.6 Sample transfer & derivatization
Transfer and derivatization procedures were slightly modified
as described by Boertz et al.
10
After incubation the cell media
flasks were stored at 80 1C for three hours and subsequently
Table 1 Operating conditions for the GC/EI-MS/ICP-MS instrument
GC conditions
Column DB-5 MS, 30 m 250 mm25mm
Initial head pressure 254.8 kPa
Inlet Conditions PTV
Split 1 : 50
Initial temperature 100 1C for 10 min
Heating rate 800 1C/min
Final temperature 250 1C for 11 min
Oven programme
Initial temperature 60 1C
Cooling rate 1 100 1C/min
Final temperature 1 35 1C for 10 min
Heating rate 2 30 1C/min
Final temperature 2 230 1C for 10 min
EI-MS parameters
Mass window 200–400 amu
Transfer line temperature 280 1C
MS Quad temperature 150 1C
Ionisation energy 70 eV
ICP-MS parameters
Argon flow 15 l/min
Carrier gas 0.79 l/min
Makeup gas 0.23 l/min
RF-Power 1540 W
Sampling depth 5.0 mm
Isotopes monitored (dwell time)
203
Tl,
205
Tl,
209
Bi (0.1 s)
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warmed to room temperature for lysis of the cells. Each liquid
phase was transferred by a 10 ml syringe, penetrating both
septum and cap of the cell media flask, into an empty 25 ml
glass vial closed with a butyl-rubber septum. Subsequently the
vial was placed in a helium purge gas flow and 1 ml of sodium
tetraethylborate solution (1% w/w) (Galab, Geesthacht,
Germany, stabilized by 2% ( w/w) KOH-solution) and
100 ml Antifoam 289
s
were added for ethylation. Finally the
headspace was purged for 10 minutes to a packed liner that
was cooled to 100 1C.
3. Results and discussion
3.1 Standard identification
For identification of bismuth cysteine and bismuth glutathione
ESI-HR-TOF-MS (positive mode) was performed. The spectrum
of bismuth cysteine shows dominant ions at m/z = 449.0033
[M + H]
+
, which are consistent with the expected molecular
ion (calculated 449.0037 amu) indicating the formula
BiC
6
H
12
N
2
O
4
S
2
(BiCys
2
). BiGSH
2
was identified at m/z =
822.1396 [M + H]
+
in good agreement with the calculated
value of the chemical formula BiC
20
H
33
N
6
O
12
S
2
(calculated
822.1402 amu). No significant impurities could be detected in
ESI-MS.
3.2 Bismuth detection after incubation
Correlation of the ICP-MS signal and TIC of EI-MS revealed
all bismuth containing compounds. As shown in Fig. 1a, two
bismuth containing compounds (peaks b and d) were detected
by ICP-MS as well as EI-MS after incubation of HepG2 with
both bismuth cysteine and CBS.
A magnified view of the TIC (EI-MS) gave six representative
peaks which were named as shown in Fig. 1. Taking the
ICP-MS signal into account only peaks b and d represented
bismuth compounds. All other peaks had their origin in
siloxanes which could be derived from either the GC column
or the Antifoam agent, which was added during sample
preparation.
Peaks b and d were identified by interpreting the fragmentation
of these compounds as shown in Fig. 2a and b.
Consequently, these compounds could be identified as
methylbismuth and an inorganic bismuth species forming
diethyl methylbismuth and triethyl bismuth after derivatization
by sodium tetraethyl borate.
Both chromatograms and mass spectra of bismuth cysteine
and CBS, were identical. Peaks a, c, e and f could be identified
as siloxanes D3, D4, D5 and D6 by matching the spectra with
the NIST database. Considering the blank values (ESI,w
Fig. S2 and Fig. S4) their origin is probably the added
Antifoam agent.
In contrast, incubation with bismuth glutathione did not
lead to the methylated bismuth compound as shown in
Fig. 1b.
The methylbismuth species giving peak b did not occur in
the chromatogram. For ethylation it is known that artifact
formation can happen.
28
So we observed carefully the formation
of monomethyl species during ethylation of inorganic bismuth
compounds.
As Fig. 3 demonstrates, no methylated species occurred
during ethylation of the cell culture medium without hepatic
cells containing bismuth compounds, nor did methylated
bismuth species occur after adding sodium tetraethyl borate
to a non-incubated sample of HepG2 in cell culture medium.
For ethylation of bismuth it turned out to be important to
buffer the solution to a pH value of about 7–8.
Many independent studies have shown that TMBi is a
volatile bismuth species detected in biological and environmental
samples
10,19
although the heat of formation DH
f
= 194 kJ/mol
29
is rather high. This means permethylation of bismuth is an
energetically inappropriate process. Nevertheless TMBi was
detected, which can be explained by catalytically mediated
biomethylation. Likewise, an exchange of methyl groups
by monomethylated bismuth species as well as a stepwise
methylation in the human liver is possible. An earlier work
of Hirner and co-workers underlines the time shifted transfer
of methyl groups to bismuth by monitoring the increase
and decrease of methylated bismuth species in the blood of
bismuth exposed probands.
24
Nevertheless, further investigations have to be carried out to
close the gap between mono- and trimethylated bismuth
species both in vitro and in vivo.
One possible explanation of why bismuth cysteine enters
the cells is that it uses amino acid carriers. Since bismuth
glutathione is a possible excretion of HepG2, an intake into
Fig. 1 (a) Ethylation of hepatic cells incubated with BiCys
2
revealed
two bismuth containing compounds b and d. (b) Using BiGSH
2
for
incubation instead, peak b does not occur in the chromatogram.
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The Royal Society of Chemistry 2010
these cells is very unlikely. This mechanism is well studied for
mercury cysteine by Clarkson et al.
30
The intake of CBS can be
explained by the possible formation of an amino acid complex
of bismuth by amino acids that are part of the MEM solution.
Due to the lack of suitable bismuth standards and reference
materials a quantitative reflection of the results is hardly
reliable. Nevertheless, assuming that both methylated and
non-methylated bismuth species have similar derivatization
efficiencies, comparison of their resulting peak areas in ICP-MS
chromatograms shows that approximately 2–3% of the inorganic
bismuth species were methylated.
The values listed in Table 2 are given to make a rough
estimate of bismuth conversion rates by hepatic cells. Since
there are no reliable standards available for analytical
balancing, we had to assume that there are no different effects
on methylated and non-methylated bismuth compounds
during derivatization and ionization, respectively.
Furthermore, to prevent the potential loss of volatile
bismuth species, no gas was exchanged during incubation,
although HepG2 cells require proper gas exchange for
viability. So the methylation yields could also be limited by
cell lifetime without oxygen.
Since this study was planned as a qualitative experiment
only, we did not determine LODs. Typical LODs for volatile
bismuth species on our analytical system are 0.1 to 0.3 ng per
m
3
of gaseous sample.
10
Conclusions
In summary, it was shown that CBS as well as bismuth
cysteine is methylated by HepG2 cells, in contrast to bismuth
glutathione which is not methylated. This indicates a species
dependent intake of bismuth into human hepatic cells and
supports the findings of von Recklinghausen et al.
11
that no
significant uptake of bismuth gluthathione was observed.
Further investigations for clarification of which is the
dominant species in the cells will be carried out. Likewise it
has to be specified whether the monomethyl bismuth species
were excreted by the cells or if they were still inside the cells and
could only be detected because of the lysis. With respect to the
analytics used, the sensitivity and ability of elemental detection
of ICP-MS hyphenated to GC/EI-MS providing structural
information is a powerful tool in bismuth speciation analysis.
The ICP-MS signal directly indicates where to look for
bismuth-containing compounds. Otherwise an identification
of bismuth compounds by EI-MS spectra alone would be more
complicated, since bismuth is a monoisotopic element which
subsequently has no characteristic isotope pattern. Moreover
selected ion monitoring at m /z = 209 is not significant since
this fragment is dominated by siloxane fragmentation
originating from the Antifoam agent or from the GC column.
Besides this, we could show that hepatoma cells are able to
methylate CBS and bismuth cysteine but not bismuth
glutathione. These results show that human hepatoma cells
have the potential to methylate bismuth and that the
permethylated species is not generated within the observed
period of time. If methylation was not observed as in the case
of bismuth glutathione, this might result from the low uptake
of this compound into the hepatoma cells. In conclusion, this
study shows that bismuth is methylated by human hepatic cells
in vitro. It appears from the result that both the intestinal
microflora and the liver could be involved in bismuth bio-
transformation in the human body. In future studies, after
suitable standards for method validation are available, further
investigations concerning the transformation process and the
cellular distribution of bismuth compounds should be done.
Acknowledgements
We would like to thank Prof. A. W. Rettenmeier (Institute of
Hygiene and Occupational Medicine, University of Duisburg-
Essen, Germany) for providing the facilities to perform the cell
Fig. 2 (a) Fragmentation of peak b indicating diethyl methyl
bismuth. (b) Fragmentation of peak d indicating triethyl bismuth.
Fig. 3 Ethylation of inorganic bismuth compounds in HEPES showing
no methylated species. Peak b at t
r
= 11.564 min is not observed.
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The Royal Society of Chemistry 2010 Metallomics, 2010, 2, 52–56 | 55
culture experiments. We would also like to thank the team of
technical assistants, especially Mrs Zimmer for helping us in
different ways while performing the cell culture experiments.
This work was financed by the German Research Foundation
(Deutsche Forschungsgemeinschaft; DFG) ‘‘Synthesis and
analysis of bismuth species with biological relevance’’ (‘‘Synthese
und Analyse biologisch relevanter Bismutspezies’’).
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Table 2 Conversion rates of inorganic to methylated bismuth species
Compound Conversion rate
a
[%] Absolute amount of methylated Bi
a
[mg]
CBS E2 E4
BiCys
2
E3 E3
BiGSH
2
b
b
a
10
6
cells were used.
b
Conversion of BiGSH
2
was not observed.
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In conjoining the disciplines of "ethology" and "chemistry" the field of "Ethochemistry" has been instituted. Ethochemistry is an effective tool in conservation efforts of endangered species and the understanding of behavioral patterns across all species. Chemical constituents of scent-markings have an important, yet poorly understood function in territoriality, reproduction, dominance, and impact on evolutionary biology, especially in large mammals. Particular attention has recently been focused on scent-marking analysis of great cats (Kalahari leopards (Panthera pardus), puma (Puma concolor) snow leopard (Panthera uncia), African lions (Panthera leo), cheetahs (Acinonyx jubatus), and tigers (Panthera tigris)) for the purpose of conservation. Sensory analyses of scent-markings could address knowledge gaps in ethochemistry. The objective of this review is to summarize the current state-of-the art of both the chemical and sensory analyses of scent-markings in wild mammals. Specific focus is placed on sampling and sample preparation, chemical analysis, sensory analysis, and simultaneous chemical and sensory analyses. Constituents of exocrine and endocrine secretions have been most commonly studied with chromatography-based analytical separations. Odor analysis of scent-markings provides an insight into the animal's sensory perception. A limited number of articles have been published in the area of sensory characterization of scent marks. Simultaneous chemical and sensory analyses with chromatography-olfactometry hyphenation could potentially aid conservation efforts by linking perceived odor, compounds responsible for odor, and resulting behavior.
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Building on the first principles of environmental chemistry, engineering, and ecology, this volume fills the need for an advanced textbook introducing the modern, integrated environmental management approach, with a view towards long-term sustainability and within the framework of international regulations. As such, it presents the classic technologies alongside innovative ones that are just now coming into widespread use, such as photochemical technologies and carbon dioxide sequestration. Numerous case studies from the fields of air, water and soil engineering describe real-life solutions to problems in pollution prevention and remediation, as an aid to practicing professional skills. With its tabulated data, comprehensive list of further reading, and a glossary of terms, this book doubles as a reference for environmental engineers and consultants.
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Antimony and bismuth are in Group 15 of the periodic table. They display important impacts on biological systems and are being used as components of anti-parasitic, antimicrobial or anti-cancer drugs. In this chapter, the general scenarios of binding and transport of antimony (as Sb(III) and Sb(V)) and bismuth (as Bi(III)) in biological systems are summarized. Both can be biomethylated by different mechanisms, including enzymatic catalysis. Antimonate (Sb(V)) can be reduced to the more toxic antimonite (Sb(III)), both enzymatically and non-enzymatically. Sb(III) transporters are ubiquitously present in organisms as aquaglyceroporin protein channels. To acquire resistance to antimony, organisms rely on several protein systems that extrude intracellular antimony. Selected antimony-binding proteins have been identified and structurally characterized and more can be identified by proteomic approaches. Binding of Bi(III) to proteins and enzymes offers information on transport of the metal ions in biological systems. Further work is required to uncover their medicinal potentials as well as understand their toxicity.
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After the synthesis and isolation of methylated bismuth cysteine, its initial identification by IR-spectroscopy was performed, whereas for definitive identification, high resolution mass spectrometry (ESI-TOF-MS and LTQ Orbitrap) was carried out.
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5 Cases of bismuth associated encephalopathy have been observed in the area of Geneva (Switzerland). The typical clinical picture is described and the blood and urinary bismuth levels are analyzed in comparison with a group of patients on bismuth treatment but without encephalopathy. A link is established between these observations and previously reported cases of bismuth toxicity, and also with other toxic encephalopathies. With regard to pathogenesis, 2 hypotheses are discussed: alkylation of bismuth in vivo, and association with another neurotoxic element. With this in view, the urinary excretion of arsenic, lead and mercury was measured. The results were within normal limits.
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Here some information, quoted from Google Books: "Inorganic Chemistry easily surpasses its competitors in sheer volume and depth of information. Readers are presented with summaries that ease exam preparation, an extensive index, numerous references for further study, six invaluable appendixes, and over 150 tables that provide important data on elements at a quick glance. Now in its 101st printing, Inorganic Chemistry provides an authoritative and comprehensive reference for graduate students, as well as chemists and scientists in fields related to chemistry such as physics, biology, geology, pharmacy, and medicine. Translated for the first time into English, Holleman and Wiberg's book is a bestseller in Germany, where every chemist knows and values it. Prior to this translation, there was no equivalent to Holleman and Wiberg's book in English". Please note that there is no ‘full text’ available. The book was published in 2001 and as far as known, there is no digital version. Also, it is long – 1884 pages – and is still under copyright.
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The presented technique combines the quantitative benefits characteristic of element specific inductively coupled plasma mass spectrometry (ICP-MS) techniques with the advantages of highly selective and molecule specific electron ionisation mass spectrometry (EI-MS) detection by parallel hyphenation of these detectors. As proof of concept, parallel detection of four iodinated alkanes (iodomethane, iodoethane, 1-iodopropane, 2-iodopropane) with EI-MS and ICP-MS after capillary gas chromatography (GC) is demonstrated. Analytical figures of merit resulting from linear calibration are presented and compared with respect to the two different detectors. Limits of detection (0.6 pg as iodine) comparable to values reported in literature were achieved for ICP-MS detection of all investigated species.
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This paper describes the synthesis, crystal structure, and aqueous solution behavior of a polymeric bismuth citrate compound (NH4)(12)[Bi12O8(cit(4-))(8)](H2O)(10) (1). Compound 1 was obtained from an aqueous solution containing commercially available bismuth citrate (BiC6H5O7) in the presence of ammonia, which crystallizes in the rhombohedral space group <R(3)over bar> with a = b = 17.807(3) Angstrom, c = 31.596(6) Angstrom, V = 8684(4) Angstrom(3), and Z = 3. The structure solution and refinement based on 1203 reflections with I = 3 sigma(I) converged at R = 0.055 and R(w) = 0.062. The polymeric structure of compound 1 is attained by carboxylate bridges from citrates in an anionic dodecanuclear bismuth-oxo citrate cluster unit [Bi12O8(cit(4-))(8)](12-). The dodecanuclear unit with a symmetry of inversion can be composed of two hexanuclear [Bi6O4(cit(4-))(4)](6-) cluster units, each of which uses three carboxylate bridges from three crystallographically equivalent citrate ions to connect the units. A fourth citrate in the smaller cluster unit does not obey the 3 symmetry within one unit but does obey the symmetry in the crystal lattice by orientational disorder. The solution behavior of compound 1 has been investigated by using H-1 and C-13 NMR spectroscopy. In highly concentrated solutions, the Bi-12 clusters are still aggregated to some extent. However, the order of aggregation decreases with a decrease in the concentration, resulting mixtures of Bi-12, Bi-24, and (Bi-12)(n) species. In diluted solutions, even the Bi-12 unit (or the smaller unit Bi-6) undergoes hydrolytic decomposition to release free citrates. Furthermore, when an excess of free citrate is added to the diluted solution, the cluster species completely decomposes, resulting in the ligand exchange process, and all citrates become averaged on the NMR time scale. The solution behavior of compound 1 was compared with that of earlier reported bismuth citrate compounds, including commercially available colloidal bismuth subcitrate (CBS; a well-known ulcer-healing agent), leading to the conclusion that solid samples of CBS which are amorphous could be formed by aggregation of the dinuclear building block [(cit(4-))BiBi(cit(4-))](2-) through citrato bridges and hydrogen bonding.
Article
Biomethylation of metals and metalloids of Group 14 and 15 metals such as tin, lead and arsenic takes place in the environment, but information about methylated bismuth compounds is rather limited, although bismuth compounds are used widely in alloys, cosmetics and pharmaceutical products.Cryotrapping gas chromatography and hydride generation gas chromatography coupled with an ICP–MS as a bismuth-selective detector were used to determine volatile bismuth compounds in landfill and in sewage gas, as well as non-volatile methylated compounds in water and sediment samples.One volatile bismuth compound could be determined in gaseous samples; it was identified as Me3Bi (TMB) by element-specific detection (ICP-MS, m/z 209), matching the retention time with a TMB standard. The molecular structure was recently confirmed by gas-chromatographic fractionation with MS–ion trap detection (electron impact). Among other volatile metal compounds, TMB is a major component in the gases of sewage sludge digesters: concentrations of up to 25 µ<?tf="PS2B61">g m−3 have been measured at eight sewage treatment plants. The concentration in landfill gas was approximately one order of magnitude lower.In laboratory experiments, fermentors containing an anaerobic culture from a clean pond sludge were mixed with contaminated soil from four different industrial areas. After an incubation time of two weeks at 30 °C in the dark, TMB was detected in the headspace of all the samples. The volatilization rate of bismuth did not correlate with the total amount of bismuth in the sediments or with the available fraction after acid digestion following hydride generation. Some evidence was obtained for the occurrence of methylated bismuth compounds in water samples and in sediments. Copyright © 1999 John Wiley & Sons, Ltd.
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In this study the bioconversion of bismuth to volatile derivatives was investigated in cultures of the common sewage sludge methanogen Methanobacterium formicicum. The production of volatile bismuth compounds was analysed during growth of M. formicicum with respect to the concentration and chemical formulation of the applied bismuth. The main volatile bismuth compound detected in the culture headspace was trimethylbismuth (TMBi), with a maximum conversion rate of up to 2.6 ± 1.8% from spiked 1 µM bismuth nitrate [Bi(NO3)3] in the culture media. This main compound proved to be stable under the incubation conditions in a CO2–H2 atmosphere. Bismuthine and the partially methylated bismuthines monomethylbismuth hydride and dimethylbismuth hydride were additionally detected in the late exponential growth phase, but only in the presence of low concentrations of spiked Bi(NO3)3 (10 nM, 100 nM). The conversion of bismuth to TMBi from the bismuth-containing pharmaceuticals Bismofalk® [containing bismuth subgallate and Bi(NO3)3] and Noemin® (containing bismuth aluminate) could also be observed, however, with a lower rate than found for Bi(NO3)3. In vitro experiments with crude extracts of M. formicicum suggest that the methylation of bismuth is mainly catalysed by enzyme-catalysed reactions with methylcobalamin as methyl donor. Copyright © 2002 John Wiley & Sons, Ltd.
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Biological methylation and hydride formation of metals and metalloids are ubiquitous environmental processes that can lead to the formation of chemical species with significantly increased mobility and toxicity. Whereas much is known about the interaction of metal(loid)s with microorganisms in environmental settings, little information has been gathered on respective processes inside the human body as yet. Here, we studied the biotransformation and excretion of bismuth after ingestion of colloidal bismuth subcitrate (215 mg of bismuth) to 20 male human volunteers. Bismuth absorption in the stomach and upper intestine was very low, as evidenced by the small quantity of bismuth eliminated via the renal route. Total bismuth concentrations in blood increased rapidly in the first hour after ingestion. Most of the ingested bismuth was excreted via feces during the study period. Trace levels of the metabolite trimethylbismuth [(CH(3))(3)Bi] were detected via low temperaturegas chromatography/inductively coupled plasma-mass spectrometry in blood samples and in exhaled air samples. Concentrations were in the range of up to 2.50 pg/ml (blood) and 0.8 to 458 ng/m(3) (exhaled air), with high interindividual variation being observed. Elimination routes of bismuth were exhaled air (up to 0.03 per thousand), urine (0.03-1.2%), and feces. The site of (CH(3))(3)Bi production could not be identified in the present study, but the intestinal microflora seems to be involved in this biotransformation if accompanying ex vivo studies are taken into consideration.