Rainer Herzschuh

Determination of urinary acylcarnitines by ESI‐MS coupled with solid‐phase microextraction (SPME)

The determination of selected short-, medium- and long-chain acylcarnitines by electrospray ionization mass spectrometry (ESI-MS) is discussed. The differences in fragmentation behaviour and ionization efficiency are described in dependence on collision induced dissociation (CID) conditions and mixture composition. A new method combination, solid-phase microextraction (SPME)-ESI-MS, is introduced to characterize acylcarnitines in body fluids. This method utilizes SPME for pre-concentration of acylcarnitines from complex biological samples and ESI-MS for a selective and sensitive detection. The method is presented by standard experiments determining of acylcarnitines in aqueous solutions and urine samples from patients with secondary carnitine deficiency syndromes or related disorders.

Oil residues in Baltic sediment, mussel and fish. I. Development of the analysis methods

Abstract Sediment, sediment trap, Mytilus, Macoma and flounder samples from Northern Baltic (Finnish archipelago) have been analyzed for their contents of aliphatic and aromatic hydrocarbons. Androstane and hexaethylbenzene were used as internal standards. The analysis procedure consisted of alkaline degradation of fat, column fractionation of the two residue groups and final determination by glass capillary gas chromatography with FID for aliphatic hydrocarbon group and with mass spectrometry for non-polar aromatic residue group. The latter group was also determined by high pressure liquid chromatography. The residues due to oil pollution were distinguished from compounds of pure natural origin on the basis of statistical treatment of the determination results.

Application of High-Performance Liquid Chromatography/Electrospray Mass Spectrometry for Identification of Carboxylic Acids Containing Several Carboxyl Groups from Aqueous Solutions:

A high-performance liquid chromatography/electrospray ionization mass spectrometry (HPLC/ESI-MS) method has been developed for the separation and detection of a series of carboxylic acids with one or more carboxyl groups, which can be formed during air oxidation of lignite. Chromatographic separation used an RP-C18 column with a gradient of water [containing 0.01% (v/v) formic acid] and acetonitrile, at a flow rate of 0.3 mL min−1. Detection by means of megaflow electrospray-MS was performed in the negative-ion mode [ESI(–)] at different cone voltages. The ESI(–) mass spectra of the carboxylic acids at a cone voltage of −20 V are characterized by the formation of [M – H]− anions together with fragmentation by loss of CO2 and sometimes H2O. Increasing the cone voltage effects enhanced fragmentation and leads to further structural hints. Lignite-derived analytes used for these HPLC/ESI-MS investigations were enriched from aqueous solution by solid-phase extraction on ISOLUTE ENV+, a polystyrene copolymer. From fragmentation results obtained with standards, conclusions regarding the existence of a variety of carboxylic acids containing one or more carboxyl groups could be drawn. A more definitive structural elucidation is possible when these results are used in combination with data from GC/MS (after analyte derivatization).

Laser Desorption/Ionisation of Fluorinated Fullerenes

Laser desorption/ionisation time-of-flight (LDI-TOF) mass spectrometry has been applied to fluorinated fullerene samples of varying fluorine content. The formation of positively and negatively charged ions from highly fluorinated fullerenes is discussed in comparison with earlier desorption experiments. The negative-ion LDI mass spectra of fluorofullerenes with different fluorine content are contrasted with the molecular-ion region of spectra obtained under electron impact conditions. A complementary approach to investigate the formation and fragmentation features of anions involves matrix-assisted LDI-reflectron TOF mass spectrometry and liquid secondary ion mass spectrometry in conjunction with high-energy collisions utilizing a four-sector tandem mass spectrometer.

PCDD/F in flue gas and in bottom ash of lignite domestic combustion and the role of the salt content of the burned briquettes

Lignite briquettes with different salt contents (“normal”-coal: 300 ppm w/w, “salt”-coal: 2000 ppm w/w) were burned in a common type of a house heating facility. The content of polychlorodibenzodioxins and furans (PCDD/F) in the flue gas and in the bottom ash were determined. The values calculated from the homologue sums were significantly higher for the “salt”-coal briquettes regarding their flue gas concentrations and slightly increased in respect to the bottom ashes. Taking in account a wide variety of additional analytical parameters and considering mechanistic aspects, our assumtion was proved that the higher chlorine content of the “salt”-coal briquettes is responsible for these increased values. The evaluation of the homologue profiles and the isomer distribution shows that the mechanism of the formation of PCDD/F in the flue gas is similar for both coal sorts; whereas, however, the formation of these compounds in the bottom ashes occurs under different conditions. Based on the quantitative results, an assessment of lignite domestic heating as source of PCDD/F is given.

An XPS investigation of the effects of heat treatment on the chlorine surface chemistry of some lignites

X-ray photoelectron spectroscopy (XPS) was used to study the conversion of inorganic chlorine (chloride salts) to CCl bonds and subsequently chloro-organics on the surface of lignite by heat treatment at 300 °C in humid air. It is shown that a naturally chloride-rich lignite can form chloro-organics by heat treatment without added catalysts. The XPS method was used to verify CCl bonds on the lignite surface as a necessary condition of chloro-organic formation according to the so-called de novo synthesis. The chloro-organics were formed in a layer on the lignite surface with a chlorine content significantly higher than on the original surface. This implies that under the influence of air, chloride ions moved to the lignite surface, with subsequent oxidation and formation of CCl bonds on the surface, allowing subsequent release of toxic PCDDs and PCDFs.

Synthesis of (R)-4,4,4-trifluoro-2-mercaptobutyric acid

Abstract Syntheses of (R)-4,4,4-trifluoro-2-mercaptobutyric acid from (S)-malic acid via a Mitsunobu reaction and from (rac)-thiomalic acid on enzymatic resolution, using Pseudomonas cepacia (Amano lipase PS), are described. A new method for direct determination of ees for (R)- and (S)-4,4,4-trifluoro-2-mercaptobutyric acid derivatives by HPLC on a polysaccharide phase is disclosed.

Analysis of slags and filter dusts from aluminum recycling processes

Abstract In filter dusts and slags from an aluminum recycling process levels of PCDD/PCDF were determined. De-novosynthesis was postulated as a possible way of PCDD/PCDF formation confirmed by MVDA, which was performed on homologue pattern of the measured data compared to numerous data from literature. Furthermore, comparable concentrations of PCB, PCBz and PAH were detected. The contaminated filter dusts were subjected to detoxification experiments.

Komplexkatalyse: XXIII. Elektronenstoss-induzierter zerfall von η3-allylbromo(ligand)nickel(II)-komplexen C3H5NiBrL und einfluss der stärke der nickel—ligand-bindung auf die katalytische wirkung kationischer allylnickel(II)-komplexe [C3H5NiL2]PF6 für die 1,4-polymerisation des butadiens☆

The EI-mass spectra of nine η3-allyl bromo(ligand)nickel(II) complexes of the type C3H5NiBrL (L = monodentate neutral ligand) were recorded. The predominating fragmentation path is the reversed formation reaction leading to the ligand L and bis(η3-allylnickel(II) bromide), respectively. The relative strength of the NiL bond derived from the MS data is compared with the ligands influence on the catalytic activity and selectivity of the corresponding η3-allylbis(ligand) complexes [C3H5NiL2]PF6 for the 1,4-polymerisation of 1,3-butadiene.

Direct fission versus sequential evaporation mechanism of sputtered caesium iodide cluster ions

A triple stage hybrid mass spectrometer was scanned for the trapping of the reaction intermediates of the over-all loss of two CsI-moieties from size-selected caesium iodide cluster ions of the general formula Cs (CsI)+n. In addition to appropriate MS/MS/MS-methods an electrically floated collision cell has been applied to trap intermediates of unimolecular and collision-induced evaporations. In comparison with other experimental findings the features of the evaporation mechanism are discussed.