三聚氰胺在双色谱柱串联模式下的色谱保留研究

研究了亲水相互作用色谱柱串联C_(18)柱上三聚氰胺的色谱保留,并应用牛奶基质中三聚氰胺的高效分离。将HILIC柱与C_(18)柱串联,研究不同色谱柱串联顺序及色谱分离条件下三聚氰胺的保留情况,结果表明:当流动相为乙腈-乙酸铵(10mmol/L)=85∶15(v/v)、柱温30℃、流速0.75mL/min、检测波长220nm、HILIC柱在前C_(18)柱在后串联时,三聚氰胺分离效果最佳。在最佳的色谱条件下,对市售牛奶进行测定,未检测出三聚氰胺,加标回收率在81.1%～119%,三聚氰胺在双柱模式下分析效果良好。     

Design of photoresists with reduced environmental impact. II. Water‐soluble resists based on photocrosslinking of poly(2‐isopropenyl‐2‐oxazoline)

The performance of water‐ and solvent‐cast, two‐component photoresist films containing poly(2‐isopropenyl‐2‐oxazoline) or poly(2‐isopropenyl‐2‐oxazoline‐co‐styrene) with a photoacid generator has been investigated. These materials afford negative‐tone images after deep‐UV exposure and development in a suitable medium (water or toluene). Resist solutions prepared from polymers containing at least 80 mol % 2‐isopropenyl‐2‐oxazoline may be cast from and developed in pure water. Features of higher quality can be obtained when the resist is cast from 2‐methoxyethanol, probably because side reactions such as partial hydrolysis of the pendant oxazoline rings in aqueous environments are avoided. It was possible to resolve micrometer scale patterns using ca. 200 mJ/cm² of irradiation at 254 nm, followed by heating 2 min at 130°C and development in water alone. Image quality and etch resistance were improved using copolymers containing up to 20 mol % of styrene repeat units. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1225–1236, 1999     

Organic sol-gel materials for second-order nonlinear optics based on melamines

A series of all organic nonlinear optical (NLO) sol-gel materials based on melamines and an azobenzene dye (Disperse Orange 3; DO3) have been investigated. Different contents of DO3 were covalently bonded with the melamine-based organic network via condensation of amino and methylol groups. The optically clear samples exhibited second-order optical nonlinearity (second-harmonic coefficient d₃₃) = 35.4 and 11.5 pm/V at 1064 and 1542 nm, respectively) after poling and curing at 220°C for 1 h. Thermal behavior of these organic NLO sol-gel systems was studied by temperature-dependent dielectric relaxation. The results indicate that the incorporation of rigid NLO-active chromophore into the melamine-based matrix leads to high rigidity and dense packing of the organic network. Subsequently, higher glass transition temperatures were obtained for the organic NLO sol-gel material with higher DO3 content. The influence of composition on the temporal stability at 100°C was also investigated. Temporal stability at 100°C was studied as a function of system composition. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2503–2510, 1999     

Study on UV, IR and NMR Spectra of Double Hydrogen-bonded Complexes

1 INTRODUCTION Currently, the theoretical study on supermolecular system, especially on hydrogen-bonded complexes, has played an important role in the field of scientific research thanks to the development of computer te- chnique. Venkatraman[1] found that the theoretical parameters for the adduct of levulinic acid and me- lamine, predicted by HF and DFT methods, are in good agreement with the experimental data. Jür- gens[2] synthesized melem with melamine and perfor- med theoretical c…     

The Reaction Mechanism of the Transetherification and Crosslinking of Melamine Resins

Melamine formaldehyde resins (MFR) are well known resins in the wood board and paper coating market. Etherified MFR's are applied as crosslinkers in the automotive coating industry. In Europe the growth of the market and the research activities are relatively small. On the other side in comparison to other polymers outstanding properties are possible to realize. So the development of new melamine ether resins (MER) was started. MER is a partly methylolated and fully etherified resin with a highly stable “thermoplastic” processing range. The MER's themselves are transparent granulates with enough stability for storage and transport. The crosslinking reaction can be started either by thermal or acidic catalytic activation, without losses of formaldehyde. Transetherifications with oligomeric diols can lead to more elastic and higher molecular melamine polyether resin (MPER) structures. The reaction mechanism and the crosslinking kinetics of the partly methylolated melamine ethers of methanol in comparison to the fully methylolated hexamethylol melamine ether will be discussed in this paper.     

A line‐scan hyperspectral Raman system for spatially offset Raman spectroscopy

Spatially offset Raman spectroscopy (SORS) is a technique that can obtain subsurface layered information by collecting Raman spectra from a series of surface positions laterally offset from the excitation laser. Currently optical fiber probes are used as major tools in SORS measurement, which are either slow (single fiber probe with mechanical movement) or restricted in selecting offset range and interval (fiber probe array). This study proposes a new method to conduct SORS measurement based on a newly developed line‐scan hyperspectral Raman imaging system. A 785‐nm point laser was used as an excitation source. A detection module consisting of an imaging spectrograph and a charge‐coupled device camera was used to acquire line‐shape SORS data in a spectral region of −592 to 3015 cm⁻¹. Using a single scan, the system allowed simultaneous collection of a series of Raman spectra in a broad offset range (e.g. 0–36 mm in two sides of the incident laser) with a narrow interval (e.g. 0.07 mm). Four layered samples were created by placing butter slices with thicknesses of 1, 4, 7, and 10 mm on top of melamine powder, providing different individual Raman characteristics to test the line‐scan SORS technique. Self‐modeling mixture analysis (SMA) was used to analyze the SORS data. Raman spectra from butter and melamine were successfully retrieved for all four butter‐on‐melamine samples using the SMA method. The line‐scan SORS measurement technique provides a flexible and efficient method for subsurface evaluation, which has potential to be used for food safety and quality inspection. Copyright © 2015 John Wiley & Sons, Ltd.     

改性三聚氰胺泡塑富集-电感耦合等离子体质谱(ICP-MS)法测定矿样中的钯

钯的富集常用泡塑作为载体，而通常对泡塑的处理过程需要使用带有胺基的有机试剂，以确保泡塑的官能团带有正电荷，用于富集带有负电荷的钯络阴离子。本文选用10%(V/V)盐酸对三聚氰胺进行处理，该方法泡塑处理过程简单易实现，且对环境友好。样品用HCl-H2O2体系进行消解，避免了NO3-的引入。在盐酸浓度低于10%（V/V），振荡时间为80min时，选择高温灰化法，Pd的回收率可达到 95%以上。以铂族元素国家一级标准物质进行验证，测定值与认定值基本一致。相对标准偏差（RSD）Pd为3.73%~6.76%。可以满足大部分矿样中Pd的分析检测。