Determination of metal additives and bromine in recycled thermoplasts from electronic waste by TXRF analysis

A new method for analysis of metal additives in recycled thermoplasts from electronic waste was developed, based on dissolving the samples in an organic solvent and subsequent analysis of the corresponding solutions or suspensions by total-reflection X-ray fluorescence spectroscopy (TXRF). The procedure proved to be considerably less time consuming than the conventional digestion of the polymer matrix. Additives containing Ti, Zn, Br, Cd, Sn, Sb, and Pb were analyzed in a hundred randomly selected samples from recycling, which provided an overview of the range of elemental concentrations in thermoplasts utilized for consumer electronics. The results were validated independently by instrumental neutron activation analysis (INAA), subsequent regression analysis confirmed the trueness of the chosen approach. Received: 7 February 2000 / Revised: 25 February 2000 / Accepted: 1 March 2000     

Adhesion of modified epoxy matrices to reinforcing fibers

The adhesive strength of joints between fibers and epoxy matrices modified with three types of modifiers—active diluents, thermostable rigid-chain thermoplasts, and dispersed fillers—is studied. It is shown that the introduction of modifiers increases interface strength in several cases in a particular concentration interval. The introduction of thermostable thermoplasts into epoxides is more effective. Possible mechanisms of adhesive-strength synergism for each of the modification types are discussed.     

Detection of bromine in thermoplasts from consumer electronics by laser-induced plasma spectroscopy

Laser-induced plasma spectroscopy (LIPS) was utilized for the detection of bromine in thermoplasts with flame retardants. For detection of bromine in the VUV region and UV/Vis/NIR region, two different experimental set-ups were realized. A time-resolved study of the plasma emission indicated that the detection of atomic Br lines in the VUV was complicated by the formation of molecular oxygen in the plasma. However, the limit of detection for bromine in the VUV region at 130.99 nm was significantly improved compared to the detection limit determined in the NIR region. With an optical path purged with argon, VUV-LIPS is feasible for process analysis.     

Adhesive properties of binary mixtures of some ethylene copolymers

It is shown using the example of polyolefin thermoplasts that the value of adhesion strength is determined by the mechanical properties of a composition.     

Hot-melt adhesives based on polyamides of dimerized fatty acids and adhesive compositions from oligoamidoamines and epoxy resins

The production and the application of hot-melt adhesives and adhesive compositions based on polyamide and the oligoamidoamine derivatives of dimerized fatty acids are studied. The possibility of synthesizing basic polyamide thermoplasts with desired physicochemical properties is shown.     

Recent Advances in Modern Static Devolatilization

Summary: The present paper deals with state-of-the-art static devolatilization technology for polymer melts. Recent results obtained by CFD-studies as well as by experimental testing at pilot scale are presented for the devolatilization of technical thermoplasts like polystyrene, poly (methyl methacrylate) and polycarbonate. It is shown that with the correct design of preheater and devolatilization chamber, volatiles like monomers and solvents can be efficiently removed from the polymer melt, both from the economical and technological point of view. As design criteria for the preheater, maldistribution and heat transfer efficiency are explained in detail.     

Polymer Nanocomposites Containing Fullerene C60 Nanofillers

Summary: The effect of fulleroids (fullerene C₆₀, mixture of C₆₀/C₇₀ and fulleroids soot which used for fullerenes production) and carbon fillers (carbon black, graphite) on mechanical properties of polymer nanocomposites based on reactoplasts (epoxy resins) and thermoplasts (polyamide-12) was investigated. The nanocomposites were prepared by in situ polymerization. It was found that additives of these fillers did not influenced on the properties of reactoplasts. Therefore, the tensile modulus and tensile strength of thermoplast based polymer nanocomposites are improved by about 30-40% with loading of 0.02-0.08 fulleroids materials. Best results were obtained for a mixture of C₆₀/C₇₀.     

Rheology behavior of nematic side-chain polymers in blends with thermoplasts

Peculiarities of the rheological behavior of blends composed of thermoplasts and side-chain nematic polymers have been studied. The strong role of interface interactions associated with the polymer chemical structure on the effect of rheology is shown. The influence of the nematic ordering is shown to be effective in the mechanical characteristics of blend extrudates whereas the rheology effect does not depend on the liquid crystal ordering.     

Classification of fungi by means of pyrolysis-gas chromatography-pattern recognition

Repetitive samples of three strains of the mould Penicillium were subjected to pyrolysis-gas chromatography (Py-GC). From the chromatograms, 26 peak heights were used in a subsequent SIMCA pattern recognition analysis. This data analysis gives a marked improvement in the classification of the samples (100% correct, 85% unique) in comparison with the traditional analysis based on the average chromatogram of each class (92% correct, 45% unique). The data analytical method is described in detail using the Py-GC data as an illustration.     

Rapid multiresidue determination of organochlorine and organophosphorus compounds in human serum by solid-phase extraction and gas chromatography coupled to tandem mass spectrometry

A rapid analytical method for the multiresidue determination of several organochlorine and organophosphorus pesticides and polychlorinated biphenyls in human serum samples has been developed. Analytes were isolated by solid-phase extraction using C18 cartridges with subsequent analysis by GC-MS/MS using a glass liner packed with CarboFrit in the GC injection port. Labelled surrogate internal standards (fenitrothion D6, HCB (13)C6, p, p'-DDE D8 and PCB 138 (13)C12) were added to the samples before the extraction and were used for quantitation and for quality control in the analysis of real-world samples. Accuracy and precision were evaluated by using serum samples fortified at two concentration levels for the three families of compounds, with satisfactory results in the majority of cases. The high selectivity and sensitivity of GC-MS/MS allowed low detection limits of 0.05-0.5 ng mL(-1) for most of the analytes investigated. The developed procedure improves other current methodologies for the analysis of pesticides and PCBs in biological fluids, especially as regards to analysis time and simplicity of sample treatment. The method was applied to several serum samples obtained from farmers devoted to citrus crop production. Chlorpyrifos, HCB, p, p'-DDE and the higher chlorinated PCBs (153, 138 and 180) were the most frequently detected compounds.     

Analysis of Slightly Volatile Samples by Atomic-Ionization Spectrometry with Laser Ablation into Flame

The potentialities of laser-enhanced atomic-ionization spectrometry with laser ablation for the analysis of slightly volatile and difficultly ionized samples were studied using lithium polyvanadate as an example. The effect of the cathode voltage and the power of the ablation beam on the signal in the analysis of such samples was studied. The optimum measurement range was determined as a function of the number of subsequent ablation pulses acting upon the same surface point. This minimized the effect of the surface contaminants and the change in ablation conditions as the crater deepened.     

Investigation on stability and preservation of arsenic species in iron rich water samples

Important for the accurate and reproducible determination of inorganic redox forms of arsenic in iron-rich waters is their conservation prior to analysis. Species and trace element analysis methods are commonly laboratory based. Stabilisation of samples is necessary for subsequent laboratory analysis in order to preserve the information about the system from which the samples were taken. Pre-treatment procedures based on complexation of metal ions and moderate acidification of the samples are presented. The concentration of the stabilisation agent and the storage temperature were optimised. The most satisfactory results were obtained with 0.01 mol l(-1) phosphoric acid and a storage at 6 degrees C.     

Determination of the pesticides considered as endocrine-disrupting compounds (EDCs) by solid-phase extraction followed by gas chromatography with electron capture and mass spectrometric detection

An SPE method followed by GC-electron capture detection (ECD) with confirmation by MS for the trace determination of four pesticides considered as endocrine-disrupting compounds (EDCs) in natural waters and sediments has been developed. Target analytes, fenarimol, fenvalerate, pendimethalin, and vinclozolin, belong to different chemical groups and are used mainly in agriculture. In the present study, analysis employs an offline SPE step for the extraction of the target analytes from natural waters. Sonication and subsequent SPE clean-up was used for extraction and purification of the sediment samples which were finally treated with activated copper powder. The type of SPE disk, eluents as well as solution parameters including pH value, and concentrations of salts and humic substances were examined for the efficiency of the method. The recoveries of all pesticides were in relatively high levels, ranging from 75 to 97% for waters and 71 to 84% for sediment samples. Both methods were applied to real water and sediment samples and the presence of the tested compounds was investigated.     

Thin layer distillation for matrix isolation in flow analysis

Analyte transfer from the matrix in a thin layer distillation (TLD) cell and its subsequent measurement were investigated in a flow injection configuration. We designed the cell such that the donor and acceptor streams flowed in parallel channels separated by a thin dividing wall. The matrix transfer process involved room-temperature distillation of the analyte into the headspace of the TLD cell and its subsequent condensation/uptake by a concurrently flowing acceptor stream. There are no membranes; hence there are no membrane-related problems. The TLD system design was optimized with respect to its dimensions and operational parameters. Throughput and sensitivity were compared with a conventional pervaporation flow injection (PFI) system for ammonia and five different amines. For the higher molecular mass amines, the TLD approach provided comparable or superior performance. The TLD technique should be an attractive approach for online analysis of volatile chemical species in ‘dirty’ samples, especially for volatile analytes of higher molecular mass.     

Assessment of quality consistency in traditional Chinese medicine using multi‐wavelength fusion profiling by integrated quantitative fingerprint method: Niuhuang Jiedu pill as an example

Under the wave of the revival of traditional Chinese medicine, there is a quite imperative duty to study an integrated and comprehensive method of fingerprint data processing and analysis on the quality consistency of traditional Chinese medicine. So, we proposed six parameters from two aspects (qualitative and quantitative), three levels (biased to strong peaks, biased to weak peaks, no obvious bias), to comprehensively evaluate the similarity of the two fingerprints. On this basis, another five parameters were proposed to evaluate the integrated effects (consistency, volatility, and similarity). This method was applied to 22 batches of Niuhuang Jiedu pill samples. Next, a practical and convenient multi‐wavelength fusion method was designed to provide more information, and the generated fusion profilings were used for subsequent evaluation. The characteristics of the parameters were confirmed by correlation analysis. The results of both hierarchical clustering analysis and principal component analysis for raw data and standardized data were consistent with integrated quantitative fingerprint method results. At the same time, this method gave a reasonable explanation for abnormal and dissimilar samples. This work illustrated that the proposed method was particularly suitable for similarity analysis of fingerprints and capable of ensuring the quality consistency in traditional Chinese medicine.     

Multisample preparation methods for the solvent-free MALDI-MS analysis of synthetic polymers

A limitation of any current approach using solvent-free MALDI mass spectrometry is that only one sample at a time can be prepared and transferred to the MALDI-plate. For this reason, multiple-sample preparation approaches for solvent-free MALDI MS analysis of synthetic polymers were developed that are simple and practical. One approach multiplexed sample preparation by simultaneously preparing multiple samples. With this approach, as many as 384 samples could be prepared by addition of analyte, matrix, salt, and 1-mm metal beads to each well of a 384-well disposable bacti plate, capping the plate with the lid and homogenizing all samples simultaneously using a common laboratory vortex device. Besides the time savings achieved by a single vortex step for multiple samples, an additional advantage of this method relative to previously reported solvent-free preparation methods is that the mixing volume per sample is reduced, which allows a reduction in the amount of analyte required. This method, however, still requires the transfer of each homogenized sample to the MALDI plate for subsequent analysis. Here we report a novel approach that combines multiple simultaneous solvent-free sample preparation with automatic sample transfer to the MALDI target plate. This approach reduces the possibility of cross-contamination, the amount of sample and matrix consumed for an analysis, and the time required for preparation of multiple samples. These methods were shown to provide high-quality mass spectra for various synthetic polymer standards with M(n) values to 10 kDa. The methods are efficient in that small sample amounts are required, the sample/salt/matrix ratio is not critical, and the time necessary to achieve sufficient homogenization of multiple samples is less than 5 min.     

Spectrophotometric determination of Cu(II) with sequential injection analysis

A sequential injection system, based on the reaction of Cu(II) with diethyldithiocarbamate (DDTC), was developed for the determination of Cu(II) in plant food and water samples. The extraction procedure, generally used to extract the Cu(II)–DDTC complex for subsequent analysis was eliminated in this procedure. The complex was detected spectrophotometrically in aqueous solutions at 460 nm. The physical and chemical parameters depicting the system were studied to obtain optimum conditions for sample analysis. The system developed is fully computerized and able to monitor Cu(II) in samples at seven samples per hour with a relative standard deviation of <4.50%. The calibration curve is linear from 0.5–5.0 mg/l with a detection limit of 0.2 mg/l. Interferences were reduced by introducing multiple flow reversals, to increase mixing between the reagent and sample zones, and subsequently enhance working of the masking agents (EDTA/citrate).     

Electrophoretic analysis of food dyes using a miniaturized microfluidic system

A simple and sensitive on-chip preconcentration, separation, and electrochemical detection (ED) method for the electrophoretic analysis of food dyes was developed. The microchip comprised of three parallel channels: the first two are for the field-amplified sample stacking (FASS) and subsequent field-amplified sample injection (FASI) steps, while the third one is for the micellar EKC with ED (MEKC-ED) step. The food dyes were initially extracted from real samples by employing a method that was simpler, easier, and faster compared with a standard method. The extraction of the samples was characterized by UV-Vis and electrochemical experiments. The chronoamperometric detection was performed with a glassy carbon electrode coupled horizontally with the microchip at the separation channel exit. Experimental parameters affecting the analytical performance of the method were assessed and optimized. The sensitivity of the method was improved by approximately 10,800-fold when compared with a conventional MEKC-ED analysis. Reproducible response was observed during multiple injections of samples with an RSD of <7.2% (n=5). The calibration plots were linear (r2=0.998) within the range of 1.0 nM-1.0 microM for all food dyes. LODs were estimated between 1.0 and 5.0 nM, based on S/N=3, for food dyes. The applicability of the method for the analysis of food dyes in real sample was demonstrated.     

Rapid determination of indium,nickel and copper in NBS standard reference material by substoichiometric radioactivation analysis

A method of rapid determination for indium, nickel and copper in Spinach (NBS; SRM-1570) by substoichiometric radioactivation analysis is described. The method is based on the principle that an equal amount of non-irradiated test sample is added to the irradiated standard sample and subsequent substoichiometric extraction for the irradiated test and standard samples is carried out. Indium is extracted as diethyldithiocarbamate into carbon tetrachloride, nickel as dimethylglyoximate into chloroform and copper as dithizonate into carbon tetrachloride. The radioactivities of these extracts are measured by NaI(Tl) or Ge(Li) detector coupled with pulse-height analyser. The analytical results obtained by the method were in good agreement with our published values and certified values by NBS.