Chromatographic pattern in recycled high-impact polystyrene (HIPS) - Occurrence of low molecular weight compounds during the life cycle

The analysis of the chromatographic pattern of virgin, reprocessed, thermo-oxidised, and recycled high-impact polystyrene (HIPS) proves to be a suitable and sensitive tool to assess the degree of degradation of HIPS during its first life and subsequent recycling. Different low molecular weight compounds, such as residues of polymerisation, degradation products, and additives have been identified and relatively quantified in HIPS, using microwave-assisted extraction and further analysis by gas chromatography-mass spectrometry (GC-MS). The release of residues of polymerisation has been proven to occur during reprocessing, thermo-oxidation, and in recycled samples, which may show the emissions of volatile and semi-volatile organic compounds during the life cycle of HIPS. A wide range of oxidised degradation products are formed during reprocessing and thermo-oxidation; these products can be identified as oxidised fragments of polystyrene (PS), oxidised fragments from polybutadiene (PB) phase, and oxidised fragments from the grafting points between the PS and PB phase. Real recycled HIPS samples may also contain contaminations and fragments from additives included in their original formulations; the presence of brominated fragments from flame retardants in electronic waste is here observed.     

Chromatographic biopanning for the selection of peptides with high specificity to Pb from phage displayed peptide library

Toxic heavy metal pollution is a global problem occurring in air, soil as well as water. There is a need for a more cost effective, renewable remediation technique, but most importantly, for a recovery method that is selective for one specific metal of concern. Phage display technology has been used as a powerful tool in the discovery of peptides capable of exhibiting specific affinity to various metals or metal ions. However, traditional phage display is mainly conducted in batch mode, resulting in only one equilibrium state hence low-efficiency selection. It is also unable to monitor the selection process in real time mode. In this study, phage display technique was incorporated with chromatography procedure with the use of a monolithic column, facilitating multiple phage-binding equilibrium states and online monitoring of the selection process in search of affinity peptides to Pb²⁺. In total, 17 candidate peptides were found and their specificity toward Pb²⁺ was further investigated with bead-based enzyme immunoassay (EIA). A highly specific Pb²⁺ binding peptide ThrAsnThrLeuSerAsnAsn (TNTLSNN) was obtained. Based on our knowledge, this is the first report on a new chromatographic biopanning method coupled with monolithic column for the selection of metal ion specific binding peptides. It is expected that this monolith-based chromatographic biopanning will provide a promising approach for a high throughput screening of affinity peptides cognitive of a wide range of target species.     

Directed t-Packings and Directed t-Steiner Systems

The aim of this paper is an investigation of directed t-packings and in particular of directed t-Steiner systems. A new upper bound on the number of points k for directed t-Steiner systems T(t,k,k) is obtained. We disprove a conjecture of Levenshtein on T(t,k,k) for t 3 by showing that a T(4,6,6) exists. Furthermore, it is proved that the symmetric group S ₆ can be partitioned into 30 disjoint T(4,6,6)s. Extensive computer search shows that the tight upper bound on K for t =4,5 is 6 and for t=6 is 7. The non-existence of further small directed t-Steiner systems is established, and large directed t-packings for t,4,5,6 are constructed.     

Capillary SFC-FTIR – effects of the flow-cell on chromatographic resolution

The quantitative effects on chromatographic resolution of FTIR flow-cells for detection in capillary SFC have been determined. A suitably designed cell with a volume of 500 nl was shown to cause only modest broadening of chromatographic peaks obtained from the surfactant mixture Triton X-100, showing that subsequent detection methods can therefore be used in a multi-hyphenated chromatographic ensemble. A larger-volume (980 nl) cell was found to give satisfactory results with 100 μ columns, but not with 50 μm columns. The practicability of a multi-hyphenated system was illustrated by a preliminary capillary SFC-UV-FTIR-FID study on a plant extract. Good infrared spectra were obtained, together with well-resolved UV and (subsequent) FID chromatograms.     

二氯菊酸类杀虫剂光学纯度分析方法的研究

报道了旋光性的顺式－2，2－二甲基－3－（2，2－二氯乙烯基）环丙烷羧酸（谷称顺式二氯菊酸）类杀虫剂光学纯度的色谱分析方法。光学活性杀虫剂的顺式－2，2－二甲基－3－（2，2－二氯乙烯基）环丙烷羧酸先与氯化亚砜生成酰氯，一财与S（－）－a-甲基苄胺作用，生成顺式－2，2－二氯－3－异丁烯基环丙烷羧酸非对映异构体的酰胺，经薄层色谱纯，用高效液相色谱进行分析，即可确定中间体的光学纯度。光学纯度一定的中间体经合成至最终产物，其光学纯度保持不变。     

Synthesis of two novel macroporous silica-based impregnated polymeric composites and their application in highly active liquid waste partitioning by extraction chromatography

Two kinds of novel macroporous silica-based chelating polymeric adsorption materials, TODGA/SiO2-P and CMPO/SiO2-P, were synthesized by impregnating and immobilizing two chelating agents, N,N,N',N'-tetraoctyl-3-oxapentane-1,5-diamide (TODGA) and octyl(phenyl)-N,N-diisobutylcarbamoylmethylphoshine oxide (CMPO), into the pores of SiO2-P particles. To separate minor actinides (MA(III)) such as Am(III) and Cm(III), the adsorption and elution of 13 typically simulated fission products from a 3 M HNO3 were performed. It was found that in the first column packed with TODGA/SiO2-P, all of the simulated elements were separated effectively into four groups: (1) Cs(I), Mo(VI), and the most portion of Ru(III) (non-adsorption group), (2) Sr(II), small portion of Gd(III) and all of light REs(III) (MA-lRE-Sr group), (3) most of Gd(III) and all heavy RE(III) (hRE group), and (4) Zr(IV), Pd(II), and a little of Ru(III) (Zr-Pd group) by eluting with 3.0 M HNO3, 1.0M HNO3, distilled water, and 0.5 M H2C2O4, respectively, at 298 K. MA(III) was predicted to flow into the second group along with Nd(III) because of their close adsorption-elution onto TODGA/SiO2-P. In the second column packed with CMPO/SiO2-P, MA-lRE-Sr group was separated into (1) Sr(II), (2) middle RE(III) such as Gd(III), Eu(III), Sm(III), and quite small portion of Nd(III) (MA-mRE), and (3) light RE(III) such as La(III), Ce(III), and most of Nd(III) by eluting with 3.0 M HNO3 and 0.05 M DTPA-pH 2.0, respectively, at 323 K. MA(III) was believed to flow into MA-mRE group along with Gd(III) due to their similar adsorption properties towards CMPO/SiO2-P. Based on positions of MA(III) appeared in light and heavy RE(III), an improved MAREC process for MA(III) partitioning from HLW was proposed.     

Gas chromatographic separation of isomeric aminophenols,aniline, phenol,benzoquinone and azobenzene on an HP-1 capillary column

A gas Chromatographic method for the determination of isomeric aminophenols, aniline, phenol, azobenzene andp-benzoquinone has been developed. The non-polar HP-1 capillary column has been found to be more suitable for their separation than a polar Carbowax-20M packed column. The detection limits of the compounds lie between 0.15 and 3.3 ng/l. This method has been applied for the determination of oxidation products of aniline in different reactions. It also furnishes a rapid method for the separation and quantitation of mixtures of aniline, phenol and their derivative isomeric aminophenols with linear calibrations up to at least 0.75 mM, with coefficients of variation of about 6%.     

Recognizing chromatographic peaks with pattern recognition methods III. Application of the algorithm for peak recognition in trace analysis

Summary The application of a newly developed peak recognition algorithm is shown. This algorith is based on the KNN method, one of the pattern recognition methods. It is shown that peaks with a S/N-ratio down to one can be safely recognized. This is also possible if the baseline has not only detector noise, but has other disturbances, e.g., noise signals which are generated by a reaction detector. The recognition ability of the algorithm is demonstrated by a standard chromatogram with three different concentrations and with two different sampling rates. The improvement against the classical algorithm is demonstrated. Some properties of the algorithm are discussed.     

Charakterisierung von Ionenaustauschern auf Kunstharzbasis durch Pyrolyse-Gas-Chromatographie

Zusammenfassung Die Pyrolyse-Gas-Chromatographie stark saurer Kationenaustauscher — Typ Dowex 50 W und Amberlite IR 120, 122 und 124 — und des schwach sauren Kationenaustauschers Amberlite IRC 50 führt zu gut reproduzierbaren Fingerprint-Spektren.Die Identifizierung einer großen Anzahl auftretender Pyrolyseprodukte geschieht einerseits durch Vergleich der Retentionszeiten mit denen von Testsubstanzen, andererseits mit Hilfe der Massenspektrometrie.Bei den stark sauren Kationenaustauschern ist die Zusammensetzung der Pyrolyseprodukte von der Korngröße und dem Beladungszustand abhängig. Bei den H⁺-Formen treten gegenüber den mit Metallionen beladenen wesentlich mehr schwefelhaltige Verbindungen und weniger Äthylvinylbenzol und Divinylbenzol auf. Mit steigender Ordnungszahl der Alkalielemente als Gegenion nimmt das Verhältnis m-Divinylbenzol/m-Äthylvinylbenzol zu.In den Pyrolyse-Gas-Chromatogrammen von Amberlite IRC 50 findet man bis auf CO₂ keine sauerstoffhaltigen Verbindungen. Der Einfluß des Beladungszustandes ist gering.Nach Vorliegen weiterer Untersuchungsergebnisse, besonders von anderen Austauschertypen, dürfte die Pyrolyse-Gas-Chromatographie eine geeignete Methode zur Charakterisierung von Ionenaustauschern auf Kunstharzbasis darstellen.Die Untersuchungen wurden im Rahmen des SFB 52 Analytik durchgeführt.