Gerd Knupp

Analysis of residual styrene monomer and other volatile organic compounds in expanded polystyrene by headspace solid‐phase microextraction followed by gas chromatography and gas chromatography/mass spectrometry

A method for determination of residual styrene monomer and other volatile organic compounds in expanded polystyrene (EPS) was developed using HS SPME and gas chromatography with FID. The extraction products were identified by GC/MS. Good reproducibility of the measurements with RSD values between 3.2–3.6% was achieved by extraction using a 75 μm Carboxen-Polydimethylsiloxane fiber at 60°C with 15 min sample sonication. The contents of residual styrene monomer in two samples of EPS were 153.2 and 65.7 mg/kg, respectively. Other compounds identified in EPS were pentane, benzene, toluene, ethylbenzene, isomers of xylene, n-propylbenzene, 1,2,4-trimethylbenzene, o-methylstyrene, benzaldehyde, benzyl alcohol, and acetophenone.

Application of pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and scanning electron microscopy (SEM) in failure analysis for the identification of organic compounds in chemical, rubber, and automotive industry

Abstract For failure analysis, there often is a lack of information about the component itself, such as chemical composition, temperature resistance, possible contaminants, or mechanical properties. The damage range usually is limited and not always homogeneous. Very often, only small amounts of samples are available, which may be important for recognizing the cause of damage. Traditional analytical techniques used for characterization of high molecular weight organic compounds, such as thermal analysis and Fourier transform infrared spectroscopy (FTIR), have limitations or are not sufficiently sensitive to demonstrate the change of the structure and the resulting dysfunction of used materials. The analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) has extended the range of possible tools for the characterization of synthetic polymers/copolymers or rubbers in failure analysis in various industrial fields of application, predominantly in the automotive industry. In this report, we describe applications of analytical Py-GC/MS and scanning electron microscopy in failure analysis of chemical materials such as motor vehicle brake fluids, varnishes, and rubber materials of car tires. Failure cases demanding identification of polymers/copolymers in paint on the surface of a rubber membrane from the pressure vessel of an automotive integral accumulator and identification of the composition of sludge on the surface of the compressor wall from car air conditioner are reported. Furthermore, the identification of scaling of a valve block unit from a failed medical oxygen resuscitation apparatus is demonstrated. The obtained analytical results demonstrate clearly the benefit for troubleshooting and remedial action of the technological process.

Improvement in fingerprint detection using Tb(III)-dipicolinic acid complex doped nanobeads and time resolved imaging

This paper deals with the synthesis and application of lanthanide complex doped nanobeads used as a luminescent fingerprint powder. Due to their special optical properties, namely a long emission lifetime, sharp emission profiles and large Stokes shifts, luminescent lanthanide complexes are useful for discriminating against signals from background emissions. This is a big advantage because latent fingerprints placed on multicoloured fluorescent surfaces are difficult to develop with conventional powders. The complex of 2,6-dipicolinic acid (DPA) and terbium ([Tb(DPA)3](3-)) is used for this purpose. Using the Stöber process, this complex is incorporated into a silica matrix forming nanosized beads (230-630nm). It is shown that the [Tb(DPA)3](3-) is successfully incorporated into the beads and that these beads exhibit the wanted optical properties of the complex. A phenyl functionalisation is applied to increase the lipophilicity of the beads and finally the beads are used to develop latent fingerprints. A device for time resolved imaging was built to improve the contrast between developed fingerprint and different background signals, whilst still detecting the long lasting luminescence of the complex. The developed fingerprint powder is therefore promising to develop fingerprints on multicoloured fluorescent surfaces.

Identification and Application of Corrosion Inhibiting Long- Chain Primary Alkyl Amines in Water Treatment in the Power Industry

Gas chromatography with flame-ionization detection (FID) and gas chromatography-mass spectrometry (GC/MS) with electron impact ionization (EI) and chemical ionization (PCI and NCI) were successfully used for separation and identification of commercially available longchain primary alkyl amines. The investigated compounds were used as corrosion inhibiting and antifouling agents in a water-steam circuit of energy systems in the power industry. Solidphase extraction (SPE) with octadecyl bonded silica (C18) sorbents followed by gas chromatography were used for quantification of the investigated Primene JM-T™ alkyl amines in boiler water, condensate and superheated steam samples from the power plant. Amine formulations from Kotamina group favor formation of protective layers on internal surfaces and keep them free from corrosion and scale. Alkyl amines contained in those formulations both render the environment alkaline and limit the corrosion impact of ionic and gaseous impurities by formation of protective layers. Moreover, alkyl amines limit scaling on heating surfaces of boilers and in turbine, ensuring failure-free operation. Application of alkyl amine formulation enhances heat exchange during boiling and condensation processes. Alkyl amines with branched structure are more thermally stable than linear alkyl amines, exhibit better adsorption and effectiveness of surface shielding. As a result, application of thermostable long-chain branched alkyl amines increases the efficiency of anti-corrosive protection. Moreover, the concentration of ammonia content in water and in steam was also considerably decreased.

Chemical Structures of Thermal Stable Long-Chain n-Alkyl Amines Used in Corrosion Inhibiting Formulations in Water-Steam and Heating Water Systems in the Power Industry

Gas chromatography with flame-ionization detection (FID) and gas chromatography-mass spectrometry (GC/MS) has been used for structure elucidation of long-chain primary n-alkyl amines after derivatization with trifluoroacetic anhydride (TFAA). Electron impact ionization- (EI) and positive chemical ionization- (PCI) mass spectra of trifluoroacetylated derivatives of the identified nalkyl amines are presented. The corrosion inhibiting n-alkyl amines were applied in the investigation of a new anticorrosive and antifouling formulation for water-steam circuit of energy systems in the power industry. The presented results are part of an EU-funded international collaboration with partners from research institutes and industry from Poland, Lithuania, Romania, France and Germany (EUREKA project BOILTREAT E!2426).