Speciation of the volatile organic compounds (VOCs) in solventborne aerosol coatings by solid phase microextraction-gas chromatography

A method for the speciation of solventborne aerosol coatings is presented. Propellant from an aerosol coating is transferred to a gas collection bag and is then analyzed by GC-FID. The propellant-free liquid paint is then internally standardized with a mixture of C5 to C11 normal alkanes and analyzed on a 50-meter capillary column using solid phase microextraction (SPME) with GC-FID detection. This procedure makes it possible to assign linear retention indexes to virtually all of the individual volatile solvents in the coating with subsequent identification. After identification by SPME, the coating is dispersed in a high boiling solvent, internally standardized with a material not coeluting with the coating solvents, and is then analyzed by direct GC-FID. VOC regulations in California for aerosol coatings products require that the coatings have a reactivity (product weighted maximum incremental reactivity or PWMIR) which is below a designated value. Assignment of PWMIR values to aerosol coatings requires that the amount of each individual volatile component in a coating be known. Presented at the 79th Annual Meeting of the Federation of Societies for Coatings Technology, November 5–7, 2001, in Atlanta, GA. Department of Chemistry, Polymers and Coatings, San Luis Obispo, CA 93407.     

红外光谱法表征溶胶-凝胶固相微萃取涂层

采用溶胶-凝胶法,将含高化学活性的四乙氧基硅烷(前驱体)与羟基硅油混合,以三氟乙酸为催化剂,经水解、缩合化学反应,形成溶胶体系,在石英纤维表面经陈化胶粒间聚合,形成三维网络结构的凝胶.将键合于石英表面上的凝胶作为固相微萃取涂层,采用FTIR红外光谱法表征了溶胶-凝胶的转变过程.经谱图解析,表明了四乙氧基硅烷水解形成了Si-OH基,通过与羟基硅油缩合反应形成了Si-O基,并进一步自缩合形成SiO2网络结构.溶胶-凝胶法制备固相微萃取涂层,简便易行,涂层热稳定性好,不易脱落.     

Solid‐phase microextraction (SPME) in polymer characterization—Long‐term properties and quality control of polymeric materials

Solid‐phase microextraction (SPME) in combination with GG‐MS was applied to quality control polyamide 6.6 collected for recycling and to study the long‐term properties and degradation of nitrile rubber, polyethylene, and polyamide 6.6. The migration of plasticizer and other additives reduces the service‐life and changes the properties of the material. It is also a possible health hazard, for example, legislation against the use of brominated flame retardants in plastic materials, is under discussion, and fast and reliable methods are required to detect such compounds in plastic materials collected for recycling. SPME rapidly and effectively extracted several brominated compounds from in‐plant collected polyamide 6.6. Migration of tris(2‐butoxyethyl)phosphate plasticizer and its degradation products from nitrile rubber during long‐term thermal ageing at 60 and 80°C was shown by SPME‐GC‐MS, while the plasticizer was not volatile enough to be detected by traditional HS‐GC‐MS. In accordance the number of degradation products extracted from thermo‐oxidized PE by HS‐SPME was three times larger than the number detected after HS‐GC‐MS analysis. SPME‐GC‐MS could also detect early signs of degradation in thermo‐oxidized virgin and in‐plant recycled polyamide 6.6 before any signs of degradation were observed by, for example, tensile testing or FTIR. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 867–873, 2003     

顶空固相微萃取气相色谱法测定水中多种增塑剂

采用顶空固相微萃取气相色谱法测定了水中多种增塑剂,并考察了盐效应、萃取温度、萃取时间、热解吸时间等因素对方法灵敏度的影响,该方法的线性范围为2～1000μg/L,检出限为0.06～5.5μg/L,回收率为94.55～105.76%,RSD＜4%.     

固相微萃取法(SPME)在农药残留分析中的应用

固相微萃取（SPME）是一种崭新的无溶剂萃取分离技术，SPME具有灵敏度高，无溶剂、样品用量少，而且简便、快速等优点，已成为分析方法前处理研究的一个方向。本文对固相微萃取技术及其在农药残留分析中的应用做了概述。     

Use of chitosan derivatives as solid phase extractors for metal ions

This paper shows a comparative study between the two radiation grafted chitosan derivatives viz. cross-linked chitosan (CRC) and cross-linked chitosan after hydrolysis (CRCH). These chitosan derivatives were used as solid phase extractors for several radionuclides. The uptake of ¹³⁷Cs, ^85,89Sr, ¹⁵²Eu, ²⁴¹Am, ²³⁴Th and ²³³U by CRCH and CRC was studied using batch and column methods. The K_d, exchange capacity, breakthrough capacity for different metal ions with the functionalized polymers were determined. The uptake followed the following trend: UO₂²⁺>Th⁴⁺>Cs⁺>Eu³⁺>Am³⁺>Sr²⁺ for both sorbents. It was seen that CRCH has a greater uptake of metal ions compated to CRC but CRC was more selective of the two.     

Analysis of volatile compositions of Magnolia biondii pamp by steam distillation and headspace solid phase micro-extraction

The chemical compositions of volatile components from Magnolia biondii Pamp were determined by steam distillation (SD) and headspace solid phase micro-extraction (HS-SPME) followed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) analysis. Fifty-six compounds were identified and the major volatile components were d-camphor (0.18-43.26%), 1,8-cineol (13.23-38.02%), α-terpineol (6.57-12.29%) and α-cadinene (5.53-15.15%). The comparison of the volatile components from M. biondii Pamp harvested in three regions of China was investigated. Also, the comparison of volatile components by SD and HS-SPME methods in term of isolation time, plant-consuming and chemical compositions was discussed as well. The percentages of the volatile components by HS-SPME method were found to be large difference from the corresponding one by SD method. HS-SPME technique was much faster than SD (60 min (HS-SPME)/420 min (SD)). Although the aromatic profiles between HS-SPME and SD methods showed several quantitative differences, HS-SPME may be applied routinely to analyze aromatic and medicinal plants.     

A method to characterise the volatile release of solid recovered fuels (SRF)

A method was developed and successfully applied to characterise the de-volatilisation process of solid recovered fuels (SRF). Following the definitions of the European initiative on SRF standardisation CEN/TC 343, this kind of fuels have to be produced from non-hazardous bio-residues, mixed- and mono-waste streams, and they are designated to be used either in mono- or co-combustion processes. Consequently, SRF are – in most cases – heterogeneous fuel mixtures. The de-volatilisation process was identified as highly relevant due to the nature of fuel: most SRF components do not evolve a char comparable to coal. Furthermore, large particle sizes do not allow the application of common approaches to determine kinetic parameters. The method presented in this paper relies on thermo-gravimetric analysis (TGA). By successful combination with other well-established analytical procedures, the obtainable information towards the de-volatilisation process was largely improved. The method allows a quantification of energy and elemental distribution between volatiles and char during the de-volatilisation process in relation to the particle temperature. The data can be used to compare SRF or SRF components with other “known” fuels such as lignite and biomass. Moreover, the data is suitable as input data for combustion models. Focus of this paper is the analytical procedure including the required calculations. In addition, first results are presented and some ideas towards the use of the results are discussed.     

Biotransformation of (+)‐ and (−)‐bornyl acetate using the plant parasitic fungus Glomerella cingulata as a biocatalyst

The microbial transformations of (+)‐ and (?)‐bornyl acetate were investigated using the plant parasitic fungus, Glomerella cingulata. As a result, (+)‐ and (?)‐bornyl acetate were converted to (+)‐ and (?)‐5‐exo‐hydroxybornyl acetate, (+)‐ and (?)‐5‐oxobornyl acetate and (+)‐ and (?)‐borneol respectively. The structures of the metabolic products were determined by spectroscopic data. © 2001 Society of Chemical Industry     

固相微萃取-气相色谱-质谱联机测定饮用水中的嗅、味化合物

测定水样中的土味素(Geosmin)和2-甲基异冰片(MIB)时，浓缩方法主要有闭环萃取分析和固相微萃取(SPME)分析。闭环萃取分析法检出限很低，但是费用高、操作复杂且费时较长，而美国SUPELCO推出的SPME技术克服了传统的样品预处理技术的缺陷，它无需溶剂和复杂装置，能直接从液体或气体样品中采集挥发和非挥发性的化合物，可以直接在GC、GC／MS和HPLC上分析。能与任何型号的气相或液相色谱连用，有手动和自动进样两种。本文应用SPME—GC—MS，在优化了萃取头涂层种类、萃取时间、搅拌速度、离子强度、温度和溶液的pH值等条件的基础上，对水中的嗅、味化合物(土味素和2-甲基异冰片)进行测定，结果令人满意。     

Effect of the phase ratio on the particle properties of poly(vinyl chloride) resins produced by suspension polymerization

The effects of the dispersed phase to continuous phase ratio (weight of VCM (gr)/weight of water (gr) (φ = g_VCM/g_water)) on the particle properties of a poly(vinyl chloride) (PVC) suspension were investigated experimentally. A series of experiments were performed with different φ values in a pilot‐scale reactor. The cold plasticizer absorption of the resin decreased with φ. Scanning electron micrographs showed that by the reduction of φ, many of the produced particles had a regular shape, a smooth surface, and greater porosity. An increase in φ caused a wider and multimodal particle size distribution of the produced PVC particles. The mean particle size and bulk density also increased with φ, whereas the molecular weight and polydispersity index did not change. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Structural and phase transitions in TiN-AlN and TiN-AlN-(Ni-Cr-Al) composites produced by focused solar radiation

Results are given on the effects of concentrated solar radiation on the structure and phase transitions of composite materials (CM) based on TiN-AlN. Oxidation in the TiN-AlN system leads to the formation of β-Al₂TiO₅, which prevents the diffusion of titanium and aluminum to the surface of the specimen and correspondingly is a protective barrier for the CM in air up to temperatures above 1500°C. A CM based on TiN-AlN with Ni-Cr-Al bonding has high resistance to oxidation above 1500°C. The introduction of this metal alloy into the CM favors the formation of the spinel NiCr₂O₄, which reacts with titanium and aluminum oxides to form a dense oxide film providing protection of the CM from oxidation. Then CM with compositions TiN-AlN and TiN-AlN-30% (Ni-Cr-Al) have elevated corrosion resistance above 1500°C and can be used as corrosion-resistant CM and as coatings. Translated from Novye Ogneupory, No. 9, pp. 51–53, September, 2008.     

Measurement of the local velocity of the solid phase and the local solid hold-up in a three-phase flow by X-ray based particle tracking velocimetry (XPTV)

The measurement of the local solid velocity and the local solid hold-up in three-phase flows (gas, liquid, solid) is of great interest with regard to the design of three-phase reactors. Moreover, such measurements are necessary for the validation of flow simulations of three-phase flows. The optical methods usually applied for velocity measurements such as particle image velocimetry do not work in three-phase flows. This is due to the opacity of the solid phase or/and because of the reflections and refractions that occur on phase boundaries. Other measurement methods are intrusive and very time consuming. The measurement of the local solid hold-up is even more difficult. The new X-ray based particle tracking velocimetry (XPTV), described in this paper, measures the solid velocity and the solid content simultaneously. This fast working and non-intrusive technique has already been successfully applied in a bubble column to measure the liquid velocity. XPTV is a three-dimensional three-component method. It works independently from void fraction and solid hold-up.     

Activated carbon nanofiber produced from electrospun PAN nanofiber as a solid phase extraction sorbent for the preconcentration of organophosphorus pesticides

Activated carbon nanofibers (CNFs) were derived from electrospun nanofibers with subsequent heat treatment. They were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. The applicability of activated CNFs for preconcentration and determination of organophosphorus pesticides (OPPs) was investigated by high-performance liquid chromatography with diode array detector (HPLC-DAD). Some important parameters influencing the extraction efficiency, such as amount of sorbent, pH, flow rate and amount of salt, were investigated by response surface method (RSM). The obtained results showed that this analytical method will be useful for the analysis of OPPs in tap water with high precision and accuracy.     

气相色谱法测定6种邻苯二甲酸酯痕量组分的固相萃取条件研究

利用固相萃取技术富集了水中6种邻苯二甲酸酯类:邻苯二甲酸二(2-乙基己基)酯(DEHP)、邻苯二甲酸二甲酯(DMP)、邻苯二甲酸二乙酯(DEP)、邻苯二甲酸二丁酯(DBP)、邻苯二甲酸二辛酯(DOP)、邻苯二甲酸丁基苄基酯(BBP)。借助均匀设计法及计算机回归建模优化技术对6种邻苯二甲酸酯类的固相萃取条件进行了设计与优化,得到最佳固相萃取条件为:洗脱剂配比(正己烷与丙酮的体积比)30∶1,洗脱体积2 mL,洗脱速率为4 mL/min,上样速率8 mL/min。富集后的样品用带电子捕获器的毛细管气相色谱检测,方法的线性范围为1~1 000μg/L(DMP、DEP、DOP),0.2~100μg/L(DBP、DEHP),0.1~100μg/L(BBP);线性回归方程的相关系数为0.997 0~1.000,检测限为0.01~0.4μg/L,方法回收率为69.0%~117.0%,相对标准偏差为2.2%~9.5%。     

保证大锅法生产固碱质量的措施

分析了大锅法生产固碱中影响产品质量的各种因素,并提出了解决方法。     

锅式法生产固体氢氧化钠的质量影响因素

简述了锦化化工(集团)有限责任公司锅式法生产离子膜固碱的原理及工艺流程。着重分析了影响固碱质量的各种因素,并提出了提高固碱质量的措施。