Evaluation of gel permeation chromatography to Fourier transform infrared spectrometric detection using a modified thermospray for analysis of polystyrene samples

A heated gas flow modified thermospray was used to couple gel permeation chromatography (GPC) to Fourier transform infrared spectrometry (FTIR) for the analysis of the standard polystyrene samples. Effluents from the GPC column were evaporated and the solutes were deposited as a series of spots on the surface of a moving stainless steel belt (0.025 mm thickness × 13 mm width). The belt continuously transferred the spots into the diffuse reflectance (DRIFT) accessory of the FTIR spectrometer, enabling identification of the deposited solutes by measurement of the diffuse reflectance IR spectrum. The IR spectra of the separated components showed excellent agreement of the spectral features to those of standard FTIR spectra and no thermal degradation was observed. Received: 20 May 1996 / Revised: 17 October 1996 / Accepted: 28 November 1996     

Enhanced desolvation and improved deposition efficiency by modified thermospray for the coupling of HPLC and FT-IR.

A thermospray interface was modified for the on-line coupling of normal- and reversed-phase high-performance liquid chromatography (HPLC) and Fourier transform infrared (FTIR) spectrometry. An LC/FTIR assembly was used to evaporate the column effluents and the solutes were deposited as a series of individual spots on a stainless-steel moving belt, which continuously transferred the solutes into a diffuse reflectance accessory of FTIR, enabling the identification of deposited solutes by measuring the IR spectrum. A lowered desolvation temperature of reversed-phase HPLC eluents, a higher deposition efficiency, such as 69%, and a reduction of the thermospray capillary voltage were achieved by using a heated gas flow and a heating plate. The thermospray temperature and the distance between the tip of the thermospray tubing and the surface of the belt were shown to influence the area of deposition of spots. A variation of +/- 1 degrees C could be used for a sensitive and reproducible deposition of Irganox 565 with a relative standard deviation (RSD) of 1.8 to 2.5%. The UV and FTIR chromatograms gave similar features for the HPLC-separated constituents. The interface-derived IR spectra of the constituents showed excellent agreement of the spectral features with those of the standard FTIR spectra, and no thermal degradation was found to occur.     

Application of an HPLC-FTIR modified thermospray interface for analysis of dye samples.

Previously, we developed a reversed-phase HPLC method compatible to high performance liquid chromatography diffuse reflectance Fourier-transform infrared (HPLC-FTIR) thermospray interface for the analysis of dyes. Dye separation achieved with a mixed-mode (SCX-ODS) column using a small gradient (90 to 80% water with acetic acid) and pH 3.25; 10 to 20% acetonitrile was considered to be suitable for HPLC-FTIR. A constant-voltage setting for the thermospray temperature (227 degrees C) was successfully used for this gradient condition. The HPLC-separated components deposited as a series of concentrated spots on a moving tape were scanned by specially developed HPLC-FTIR software. Excellent repeatability of the thermospray deposition FTIR chromatograms and IR spectra was obtained. The interface-derived spectra of the separated components of formulated and purified reactive dyes were compared and differences in spectral features were observed.     

Polychlorobiphenyls differentiation and identification by gas chromatography/fourier transform infrared spectroscopy

Reference infrared vapour phase spectra of 20 polychlorobiphenyls (PCBs) have been obtained by gas chromatography/Fourier transform infrared spectroscopy (GC/FTIR). These spectra are consistent with those of PCB obtained by diffuse reflectance IR spectroscopy (DRIFT) and with those of more simple molecular structures (iodochlorobenzenes, 1-bromodichlorobenzenes). The IR frequencies of the GC/FTIR spectra of PCB are assigned in terms of substitution patterns. This work shows that GC/FTIR can be a good approach for differentiation and identification of PCB in complex mixtures.     

阳离子表面活性剂在膨润土上的有序化作用及吸附热力学

绘制了不同温度下溴化十四烷基吡啶(MPB)在膨润土上的等温吸附曲线, 探讨了MPB的吸附热力学及作用机理; 并用XRD, FTIR和UV固体漫反射表征了MPB在固相上的有序化作用. 研究结果表明, MPB的吸附热力学、作用机制及有序化过程取决于其在膨润土上的负载量. 不同负载量下标准吉布斯自由能ΔGm0<0, 表明为自发吸附过程, 但存在3个不同阶段. 在低负载量(<0.8CEC)时为吸热吸附[焓变ΔHm0=7.92 kJ/mol, 熵变ΔSm0≈110 J/(K·mol)], 以阳离子交换作用吸附为主; 在高负载量阶段为放热吸附[ΔHm0=-34.41 kJ/mol, ΔSm0≈-50 J/(K·mol)], 以脂肪链间的疏水性相互作用为主; 最大吸附量随温度的升高(278 K→328 K), 从2.8CEC降低为1.5CEC, 相应的ΔHm0=-9.74 kJ/mol. 在负载量由低到高的吸附过程中, 吸附态MPB的状态从无序“液态”逐渐演变为有序“固相”, 吸附过程从熵驱动(ΔSm0>0)过渡为焓驱动(ΔHm0<0).     

应用漫反射红外光谱技术优化2-聚苯乙烯磺酰胺基乙醇树脂的合成

本文采用漫反射红外光谱法优化一种新的固相合成载体2－江西 乙烯磺酰胺基乙醇树脂的合成。聚苯乙烯磺酰氯树脂在有或没有溶剂和／或催化剂存在下与乙醇铵反应得到2－聚苯乙烯磺酰胺基乙醇树脂。漫反射红外光谱跟踪整个反应过程。结果表明，漫反射红外光谱技术是优化制备新的功能基化聚合物条件的有力工具。2－聚苯乙烯磺酰胺基乙醇树脂的优化制备条件是：聚苯乙烯磺酰氯，乙醇胺在60℃反应30min。     

Diffuse reflectance Fourier transform IR spectroscopy

Fourier transform infrared (FTIR) spectroscopy has greatly enhanced the utility and range of applications of infrared (IR) spectroscopy in chemistry. Until the development of routine FTIR instrumentation, applications of IR were essentially limited to direct transmission measurements. Newer sampling methods in FTIR spectroscopy can be successful with less than 1% throughput of the infrared radiation and yet yield a spectrum with acceptable signal-to-noise ratio. The decreasing cost of FTIR spectrometers has made a number of such sampling techniques accessible for routine applications without compromises in performance. This article will describe one of these, diffuse reflectance.     

Micro-HPLC/TLC/FTIR

Identification problems often encountered in high performance liquid chromatography (HPLC)/Fourier transform infrared spectrometry (FTIR) can be circumvented through the use of a thin-layer chromatographic (TLC) plate as deposition and infra-red sampling medium. The combination of complementary separation modes is shown to demonstrate increased resolution of the components of complex mixtures. In this particular work, the effluent from a reversed-phase microcolumn is continuously deposited on a TLC plate with alumina stationary phase. The solute remains on the plate as a continuous record of the HPLC separation, which is then analyzed by diffuse reflectance FTIR. When the HPLC separation is inadequate for full separation of the components, the immobilized HPLC chromatogram serves as a starting point for subsequent TLC separation. A number of FTIR reconstructed chromatograms and spectra which are derived from the TLC plate aid in the interpretation.     

Coordination compounds of 3d-metal 5-sulfosalicylates with thiosemicarbazide

Copper(II), nickel(II), and cobalt(III) 5-sulfosalicylate complexes with thiosemicarbazide were synthesized and characterized by elemental analyses, IR spectra, diffuse reflectance spectra, and thermo-gravimetric data.     

Reaction of 3d-transition metal nicotinates and isonicotinates with thiosemicarbazide

Reaction of iron(II), cobalt(II), nickel(II), and copper(II) nicotinates and isonicotinates with thiosemicarbazide were studied, and the resulting coordination compounds were characterized by elemental analyses, IR spectra, diffuse reflectance spectra, and thermogravimetric data.     

Synthesis and evaluation of a C8 stationary phase on a silica hydride surface by hydrosilation of 1-octyne

The silanization/hydrosilation method is used to bond an alkyne (1-octyne) to a silica hydride surface. The new bonded material is characterized by elemental analysis and diffuse reflectance infrared Fourier transform spectroscopy. The hydrophobic behavior of this material was determined by the retention characteristics of aromatic solutes and the shape selectivity as well as phase classification (monomeric or polymeric) was measured by the polycyclic aromatic hydrocarbon mixture standard reference material 869. The presence of residual silanols on the bonded phase was probed by several basic solutes at pH 7. Long-term stability studies were conducted by measuring retention and peak symmetry of basic compounds over several thousand column volumes at pH 10.     

Coordination compounds of cobalt(II), nickel(II), and zinc(II) valerates and benzoates with benzohydrazide

Coordination compounds of cobalt(II), nickel(II), and zinc(II) valerates and benzoates with benzohydrazide have been synthesized and characterized by elemental analyses, IR spectra, diffuse reflectance spectra, and thermogravimetric data.     

Fourier transform infrared quantitative analysis of sugars and lignin in pretreated softwood solid residues

Hydrolysates were obtained from dilute sulfuric acid pretreatment of whole-tree softwood forest thinnings and softwood sawdust. Mid-infrared (IR) spectra were obtained on sample sets of wet washed hydrolysates, and 45°C vacuum-dried washed hydrolysates, using a Fourier transform infrared (FTIR) spectrophotometrer equipped with a diamond-composite attenuated total reflectance (ATR) cell. Partial least squares (PLS) analyiss of spectra from each sample set was performed. Regression analyses for sugar components and lignin were generated using results obtained from standard wet chemical and high-performance liquid chromatography methods. The correlation coefficients of the predicted and measured values were >0.9. The root mean square standard error of the estimate for each component in the residues was generally within 2 wt% of the measured value except where reported in the tables. The PLS regression analysis of the wet washed solids was similar to the PLS regression analysis on the 45°C vacuum-dried sample set. The FTIR-ATR technique allows mid-IR spectra to be obtained in a few minutes from wet washed or dried washed pretreated biomass solids. The prediction of the solids composition of an unknown washed pretreated solid is very rapid once the PLS method has been calibrated with known standard solid residues.     

Detection of collagens in brain tumors based on FTIR imaging and chemometrics

Fourier transform infrared (FTIR) imaging has been used as a molecular histopathology tool on brain tissue sections after intracranial implantation and development of glioma tumors. Healthy brain tissue (contralateral lobe) as well as solid and diffuse tumor tissues were compared for their collagen contents. IR spectra were extracted from IR images for determining the secondary structure of protein contents and compared to pure product spectra of collagens (types I, III, IV, V, and VI). Multivariate statistical analyses of variance and correspondence factorial analysis were performed to differentiate healthy and tumor brain tissues as well as their classification according to their secondary structure profiles. Secondary structure profiles revealed that no collagen was present in healthy tissues; they are also significantly different from solid and diffuse tumors (p < 0.05). Solid and diffuse tumors could be discriminated with respect to the secondary structure profile of fibrillar and non-fibrillar collagens, respectively. We can thus propose to develop FTIR imaging for histopathology examination of tumors on the basis of collagen contents.     

Quantitative assessment of organic compounds adsorbed on silica gel by FTIR and UV–VIS spectroscopies: the contribution of diffuse reflectance spectroscopy

Different spectroscopic methods are compared to quantitatively determine organic compounds adsorbed or grafted on silica. The studied example is a derivative 1 of a well known photosensitizer, benzophenone. Transmission FTIR, diffuse reflectance FTIR (DRIFT) and UV (DRUV) spectroscopy are used to measure the concentration of adsorbed 1 on silica. The diffuse reflectance spectra are treated according to the Kubelka–Munk theory. It is shown that for such a compound absorbing in the UV range, DRUV spectra actually display a linear correlation between the remission function F(R) and the concentration of adsorbed 1. As this method neither implies any sample preparation nor any problems arising from the supporting silica, it proves to be fast, efficient and with a low detection threshold. For the IR spectra, it is necessary to numerically substrate the spectrum of silica which absorbs the light in this range. Provided that some care is paid to this numerical treatment which takes the sample heterogeneity into account, transmission and DRIFT spectra also display a linear correlation between the absorbance or the F(R) function and the concentration of adsorbed 1. However, sample preparation is much easier for DRIFT spectra as no pellets are made. Moreover, the DRIFT spectra of ground samples appear easier to process than the transmission spectra because of a better baseline and resolution. Although less resolved under 1500 cm⁻¹, the DRIFT spectra of non-ground samples can also be processed and give satisfactorily and rapid results without any possible perturbation of the structural integrity of the sample.     

磁性可见光催化剂BiVO4/Fe3O4的制备及催化活性

采用超声法将磁基体Fe3O4和BiVO4复合,制备了易于固液分离的磁性可见光催化剂BiVO4/Fe3O4。采用X射线衍射(XRD)、傅立叶转换红外光谱(FTIR)、紫外-可见漫反射光谱(DRS)、透射电子显微镜(TEM)和磁学性质测量系统(MPMS)对产物进行了表征,并以亚甲基蓝为目标降解物,考察了BiVO4/Fe3O4的可见光催化活性。当BiVO4与Fe3O4质量比为5:1时,BiVO4/Fe3O4的催化活性最高,反应经过5 h,对亚甲基蓝的降解率达到92.0%,而单独使用BiVO4为催化剂,降解率仅为72.5%。这表明Fe3O4不仅起到磁基体的作用,还起到助催化剂的作用。BiVO4/Fe3O4在外加磁场的作用下很容易被分离,撤消外加磁场后,通过搅拌又可重新分散。BiVO4/Fe3O4 3次回收后的降解率仍高于80%。     

Identification of origin of coal from the Ostrava-Karvina Mining District by infrared spectroscopy and discriminant analysis

Infrared (IR) spectra of coal from five mines of the Ostrava-Karvina Mining District were collected using diffuse reflectance techniques. The spectral data were classified by the application of discriminant analysis. The aim of this paper is to test out identification of coal origin by IR spectroscopy and discriminant analysis. The results of this study confirm that infrared spectroscopy together with multivariate statistical methods could provide a powerful discriminating tool for the identification of origin of the most of coal from the Ostrava-Karvina Mining District.     

偏最小二乘法在红外光谱识别茶叶中的应用

采用漫反射傅立叶变换红外光谱(FTIR)法结合主成分分析(PCA)、偏最小二乘法(PLS)、簇类的独立软模式(SIMCA)识别法对十三种茶叶进行了分类判别研究。研究结果表明,通过多元散射校正(MSC)对原始光谱进行预处理,可以提高模式识别技术的分类判别效果。在此基础上,选取1 900~900 cm-1波长范围内的茶叶红外光谱建立识别模型,三种方法都得到了满意的分类判别效果。在对检验集中全部130个样本的判别中,PCA仅有两类样本无法判别,SIMCA的识别率和拒绝率都在90%以上,而PLS的识别效果最佳,全部样本都得到了正确的归类。这一研究结果表明傅立叶变换红外光谱法与化学计量学方法相结合可以实现茶叶品种的快速鉴别,这为茶叶的客观评审提供了一种新思路。     

A thermally stable polybenzimidazole polybenzoxazole segmented block copolymer

m-phenyl benzoate end-capped pre-polybenzoxazole oligomer and a 3,4-diaminobenzene endcapped pre-polybenzimidazole were synthesized. These functionalized oligomers were then condensed to give a polybenzoxazole-polybenzimidazole segmented block copolymer. The functionalized oligomers were characterized by proton NMR, diffuse reflectance FTIR, and thermal gravimetric analysis. The final block copolymer was characterized by diffuse reflectance FTIR and thermal gravimetric analysis.     

THE STUDIES OF THE CURING OF AN EPOXY RESIN ON COPPER WIRE BY FTIR EXTERNAL REFLECTION SPECTROSCOPY

The epoxy coating on copper wire has been studied by a modified sampling technique using Fourier transform infrared (FTIR) diffuse reflectance attachment. As the wire axis was parallel to the incident plane, a reflection spectrum of thin layer coating on a copper wire can be obtained. The study found that imidszole, especially the acetic acid treated imidazole, can be used as an effective curing catalyst of the epoxy resin on copper. This is the first report about the IR study of coatings on metal wires.