Infrared Absorption Spectrophotometry Research Articles

Didactic Sequence for the Introduction of Infrared Absorption Spectrophotometry at the High School Level

Didactic Sequence for the Introduction of Infrared Absorption Spectrophotometry at the High School Level

Synthesis and Characterization of Polypyrrole/Fe3O4 Nanocomposites: A Promising Material Against Carbon Steel Corrosion

The use of conducting polymers as coating layers for the protection of surfaces against corrosion represents an important topic for investigation, as reported in the literature. In this work, polypyrrole/Fe3O4 nanoparticles (Fe3O4_NPs/PPy) hybrid nanocomposites (HN) were incorporated as anticorrosive additives in an epoxy paint to protect SAE 1010 carbon steel from corrosion. The HN particles were obtained by chemical polymerization of pyrrole in an aqueous solution in the presence of Fe3O4_NPs and were characterized by infrared absorption spectrophotometry, dynamic light scattering (DLS), X-ray diffraction (XRD), transmission electron microscopy (TEM). The electrochemical impedance spectroscopy (EIS) was used in the analysis of the electrochemical response of the coated surface with and without HN. DLS data showed that the Fe3O4_NPs and Fe3O4_NPs/PPy obtained in solution present average diameters of (19.7 ± 9.6) nm and (63.5 ± 27.7) nm, respectively. TEM images showed Fe3O4_NPs with smaller sizes (10 nm - 30 nm), and that the HN had diameters smaller than 100 nm, consisting of Fe3O4 cores coated with polypyrrole. EIS measurements have shown that the addition of HN to the epoxy paint could improve the efficiency of the anticorrosive coating when compared to the original epoxy paint prepared without any corrosion inhibitor.

Physical and Chemical Properties and Methods of Control of Pantoprazol Sodium Sesquihydrate (Review)

Introduction. Pantoprazole sodium sesquihydrate is a proton pump inhibitor. This substance is used in the treatment of peptic ulcer of the duodenum or stomach in the acute phase, including those associated with the use of non-steroidal anti-inflammatory drugs.Text. Pantoprazole is sodium 5-(difluoromethoxy)-2-[(RS)-[(3,4-dimethoxypyridin-2-yl)methyl]sulfinyl]benzimidazol-1-ide sesquihydrate in its structure. The substance is readily soluble in water and ethyl alcohol. The identification of pantoprazole is confirmed by infrared absorption spectrophotometry, as well as by a positive reaction to sodium ion. For the assay of this substance chemical and physico-chemical methods are used. The first group of methods includes titration in a non-aqueous medium with perchloric acid and permanganatometry. Physico-chemical methods used for pantoprazole assay are spectrophotometry and HPLC. The most commonly used method is direct spectrophotometry associated with the measurement of optical density at a wavelength of the maximum absorption of pantoprazole in various solvents. In addition, spectrophotometric methods of assay are known, based on the study of the absorption of colored pantoprazode reaction products. The derivative spectrophotometry is used for the analysis of its preparations. The control of the content of impurities and pantoprazole in the substance and its dosage forms is carried out, as a rule, using HPLC.Conclusion. An analysis of the literature has shown that this substance is unstable. Therefore, this feature of pantoprazole must be considered when choosing excipients when developing a dosage form. The preferred method for analyzing pantoprazole preparations is HPLC, since it is possible to determine the substance in the presence of other compounds, which will allow one to control the quantitative content and stability of pantoprazole in the preparation.

Stability of Hassi-messaoud Asphaltenes in Media of Different Polarities

The aim of this work is to explore the floculation behavior of asphaltenes (extracted from a deposit recovered from a Hassi-Messaoud oil well) in solution in toluene according to the polarity of the flocculating medium. The flocculation thresholds related to the addition of two flocculating agents of different polarities (n-heptane and acetone) for three asphaltenic concentrations are obtained by means of near infra-red absorption spectrophotometry. The Hildebrand solubility parameters of the flocculated asphaltenic fractions are deduced using the Donnagio method based on the Flory−Huggins theory. The results obtained indicate that the interactions between the flocculated asphaltenic molecules within the toluene/acetone mixture are weaker than those in the toluene/n-heptane mixture.

Synthesis, characterization and thermal property of {Cu3(PO4)2·2H2O; Na3PO4; NaHSO4·H2O}

The phosphate compounds of copper and sodium along with sodium hydrogen sulfate monohydrate mixture has been synthesized and characterized with different measurement techniques such as Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA) and Differential Thermal Analysis (DTA), Fourier Transform Infrared (FT-IR) Spectrometry, CHNS elemental analyzer, Inductively Coupled Plasma -Atomic Emission Spectrometry (ICP-AES), Ultraviolet–Visible and near Infrared (UV–Vis-NIR) Absorption Spectrophotometry and X-ray Powder Diffraction (XRD). The thermal property of this mixture has been studied up to 573 K from 173 K in different thermal cycles with DSC. The specific heat capacity of this mixture has been measured in atmospheric O2 at a rate of 10 K min−1 in all cycles. The net specific heat capacity of this mixture is found endothermic in all thermal cycles. So, it can be used as heat storage material as a combination of sensible and latent heat technique.

Encapsulation study of citalopram and risperidone into nanostructured silica SBA-15 for in vitro release evaluation

Ordered mesoporous silica, SBA-15, presents non-toxic nature; high pore volume and high surface area; thermal, hydrothermal and mechanical stabilities. These features may enable its use as a carrier for commonly prescribed drugs in psychiatric practice: citalopram (CIT) and risperidone (RIS). Thermogravimetry/derivative thermogravimetry (TG/DTG) and ultraviolet and visible absorption spectrophotometry (UV–Vis) were used to determine drug quantity into/onto ECIT (CIT encapsulated into SBA-15), ERIS (RIS encapsulated into SBA-15), MCIT (mixture of CIT with SBA-15) and MRIS (mixture of RIS with SBA-15). All materials were characterized through: TG/DTG, differential scanning calorimetry, elemental analysis, Fourier transform infrared absorption spectrophotometry and nitrogen adsorption–desorption. A general solvent-based method for loading these psychoactive drugs into non-functionalized SBA-15 showed to retard their liberation in simulated gastric and intestinal media when compared to physical mixtures performance. It is expected that the functionalization of this nanostructured silica may increasingly extend the dissolution of CIT and RIS after encapsulation process, leading to application in controlled release systems.

Study of the Efficiency of Polypyrrole/ZnO Nanocomposites as Additives in Anticorrosion Coatings

We synthesized (ZnO nanoparticles)/polypyrrole (ZnO_NPs/PPy) hybrid nanocomposites and used them as additives in an epoxy paint to protect SAE 1020 carbon steel from corrosion. The nanocomposites were obtained by chemical polymerization of pyrrole in aqueous solution and sodium dodecyl sulfate solution containing dispersed ZnO nanoparticles. We characterized the nanoparticles by infrared absorption spectrophotometry, X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A large disparity in the distribution of ZnO particle sizes became evident from the TEM images, which also show the formation of hybrid nanocomposites consisting of polypyrrole coated ZnO nanoparticles. Electrochemical impedance spectroscopy (EIS) and open circuit potential (OCP) tests, which were performed on SAE 1020 carbon steel plates coated with epoxy and ZnO_NPs/PPy, have shown that epoxy paints have their efficiency as anticorrosive coatings significantly improved when ZnO_NPs/PPy hybrid nanocomposites are added to them.

Temperature and reaction time effects on the structural properties of titanium dioxide nanopowders obtained via the hydrothermal method

An investigation was carried out on the synthesis of titanium dioxide nanopowders via the hydrothermal method, examining the influence of temperature (150oC and 200oC) and reaction time (6 to 36 h). The resulting powders were characterized by X-ray diffraction, infrared absorption spectrophotometry, transmission electron micrographs and surface area. The X-ray diffraction revealed that there was formation of a pure crystalline phase, consisting only of anatase for all conditions of synthesis. Both temperature and reaction time proved to have a slight influence on the crystallite size (from 9 to 17 nm) and a significant influence on the surface area (from 86 to 168 m2.g-1).

Acute obstructive cholangitis caused by an enterolith in a duodenal diverticulum

they are usually asymptomatic, several complications have been reported. A 78-year-old man was admitted to our hospital with high-grade fever (39.6°C) and jaundice. His laboratory data showed liver dysfunction and elevations of the white blood cell count and serum C-reactive protein concentration. Abdominal ultrasonography demonstrated dilated biliary ducts. Abdominal computed tomography (CT) revealed a diverticulum in the second part of the duodenum (● Fig. 1). We suspected obstructive cholangitis. Endoscopic retrograde cholangiography (ERC) was performed. Gastrointestinal endoscopy revealed a periampullary diverticulum occupied by a yellow stone (● Fig. 2). ERC showed no abnormalities (● Fig. 3). Therefore, we made a diagnosis of biliary tract obstruction caused by an enterolith in the periampullary duodenal diverticulum. We performed successful endoscopic removal of the enterolith (● Fig. 4). The extracted enterolith was oval-shaped, yellowish in color, measured approximately 3 cm in diameter, and had a hard outer rim with an irregular surface (● Fig. 5). Separate layers within the wall were appreciated and there was no evidence of any nidus, such as a fruit pit. Infrared absorption spectrophotometry showed that the enterolith consisted mainly of deoxycholic acid (● Fig. 6). Duodenal diverticula are commonly encountered and are generally regarded as clinically insignificant entities. They can, however, sometimes produce serious complications, including diverticulitis, perforation, hemorrhage, biliary and/or pancreatic obstruction, partial duodenal obstruction, fistula formation with adjacent organs, diarrhea secondary to blind loop syndrome, and enterolith formation [1]. Enterolith formation is known to occur within regions of stasis, such as Meckel’s diverticulum or a blind loop, or as a result of stricture due to Crohn’s disease or tuberculosis. Duodenal diverticula may also represent such a region of stasis [2]. In conclusion, we performed successful endoscopic removal of an enterolith in a duodenal diverticulum. Obstructive cholangitis caused by an enterolith in a periampullary diverticulum is rare, but is an important entity for endoscopists.

γ-Irradiation of PEGd,lPLA and PEG-PLGA Multiblock Copolymers: I. Effect of Irradiation Doses

To evaluate the effects of different gamma irradiation doses on PEGd,lPLA and PEG-PLGA multiblock copolymers. The behaviour of the multiblock copolymers to irradiation was compared to that of PLA, PLGA polymers. PEGd,lPLA, PEG-PLGA, PLA and PLGA polymers were irradiated by using a (60)Co irradiation source at 5, 15, 25 and 50 kGy total dose. Characterization was performed on all samples before and after irradiation, by nuclear magnetic resonance (NMR), infrared absorption spectrophotometry (FTIR) and gel permeation chromatography (GPC). The effect of gamma irradiation on polymer stability was also evaluated. Results of NMR and FTIR suggest an increase in -OH and -COOH groups, attributed to scission reactions induced by irradiation treatment. Data of GPC analysis showed that the weight average molecular weight (Mw) of polymer samples decreased with increasing irradiation dose. The extent of Mw degradation expressed as percentage of Mw reduction was more prominent for polymers with high molecular weight as PEGd,lPLA and PLA. The dominant effect of gamma-irradiation on both polymer samples was chain scission. The multiblock copolymer PEGd,lPLA presented higher sensitivity to irradiation treatment with respect to PLA, likely due to the presence of PEG in the matrix. The effect of gamma irradiation continues over a much longer period of time after gamma irradiation has been performed. It is suggested that the material reacts with oxygen to form peroxyl free radicals, which may further undergo degradation reactions during storage after irradiation.

Effect of Anions on the Photocatalytic Activity of Fe(III) Salts Impregnated TiO2

This present work focuses on the photocatalytic activity of Fe(III) salt-impregnated TiO2 catalysts for studying the effect of anion on the photocatalytic activity of the salt-impregnated catalysts. The salt-impregnated TiO2 photocatalyst samples prepared using FeCl3, Fe(NO3)3, and Fe2(SO4)3 were characterized by X-ray diffraction (XRD), UV−vis diffuse reflectance spectrophotometry (DRS), Fourier transform infrared absorption spectrophotometry (FT-IR), and surface area measurement by N2 adsorption. Fe(III) ion impregnation of TiO2 with different salts is observed to influence photocatalytic degradation of acetophenone. Fe(III) salt anions were observed to influence the initial rate of degradation. For example, the initial rate of degradation of acetophenone decreases with an increase in percentage of Fe(III) ions in the case of the catalysts prepared using ferric nitrate and ferric chloride salts. However, the initial rate of degradation was observed to increase with ferric sulfate impregnated catalysts. The final percentage degradation of acetophenone was found to increase continuously with an increase in Fe(III) ion concentration, irrespective of the anion. These observations have been discussed in terms of influence of the presence of Fe(III) ions on the recombination of the electron and holes generated during UV irradiation of TiO2. Similarly, the effect of anion has been discussed in terms of radical-scavenging ability of chloride and radical-generating ability of sulfate anions.

Photocatalytic degradation of dyes and organic contaminants in water using nanocrystalline anatase and rutile TiO2

Nanocrystalline TiO2 was synthesized by controlled hydrolysis of titanium tetraisopropoxide. The anatase phase was converted to rutile phase by thermal treatment at 1023 K for 11 h. The catalysts were characterized by X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), Fourier-transform infrared absorption spectrophotometry (FT-IR) and N2 adsorption (BET) at 77 K. This study compare the photocatalytic activity of the anatase and rutile phases of nanocrystalline TiO2 for the degradation of acetophenone, nitrobenzene, methylene blue and malachite green present in aqueous solutions. The initial rate of degradation was calculated to compare the photocatalytic activity of anatase and rutile nanocrystalline TiO2 for the degradation of different substances under ultraviolet light irradiation. The higher photocatalytic activity was obtained in anatase phase TiO2 for the degradation of all substances as compared with rutile phase. It is concluded that the higher photocatalytic activity in anatase TiO2 is due to parameters like band-gap, number of hydroxyl groups, surface area and porosity of the catalyst.

Thermally Induced Deep Centers in Silicon Doped with Europium or Lanthanum

Melt-grown silicon crystals doped with europium or lanthanum were studied by capacitance spectroscopy and infrared absorption spectrophotometry. The Eu and La in the as-grown crystals were demonstrated to be electrically inactive. Annealing in the temperature range 900–1200°C produced a few deep levels in the band gap of both n-Si〈Eu〉 and n-Si〈La〉. These levels are likely related to the activation of the Eu and La impurities: Eu seems to be responsible for the levels at Ec– 0.40 eV and Ec– 0.46 eV, and La for the level at Ev+ 0.32 eV. Infrared absorption measurements indicate that heat treatment increases the concentration of optically active (interstitial) oxygen in the crystals by 15–20%.

Cytoplasmic diversity in alloplasmic common wheats with cytoplasms of Triticum and Aegilops revealed by photosynthetic and respiratory characteristics.

Photosynthetic and respiratory characteristics were surveyed to evaluate cytoplasmic diversities in alloplasmic common wheats in which a nuclear genome of common wheat (Triticum aestivum L. cv. Chinese Spring (CS)) was combined with cytoplasms of Triticum and Aegilops species. The photosynthetic capacity (PSC) was measured based on the 13CO2-assimilation rate by infrared absorption spectrophotometry. A significant variation was found in PSC. The alloplasmic line with a cytoplasm of T. monococcum ssp. boeoticum which is unique in causing severe growth depression and male sterility when combined with CS nuclei showed more than 30% higher PSC than the euplasmic CS. A negative correlation was found between PSC and growth vigor of the euplasmic and alloplasmic lines. Respiratory electron flows and the cytochrome c oxidase (COX) activity were measured polarographically by an oxygen electrode. The cytochrome path activity, the COX activity and the alternative path capacity showed significant variations among the lines, irrespective of plant tissues studied. The alloplasmic line with T. monococcum cytoplasm showed chracteristic respiration in the alloplasmic line: It significantly increased the alternative path capacity and the COX activity in roots and leaves of 2-week-old plants. Moreover, the COX activity in the roots was negatively correlated with growth vigor among the lines. The results suggested that the aberrantly high COX activity might be related to the growth depression of the alloplasmic CS with T. monococcum cytoplasm.

Teflonomas of the larynx and neck

Intracordal fluorocarbon (Teflon, Mentor O and O Inc, Norwell, MA) injection has been used for decades to correct paralytic dysphonia, a result of unilateral laryngeal paralysis. Infrequently, the Teflon extravasates and infiltrates into the soft tissues of the neck and larynx producing a mass that clinically simulates a malignant lesion. We report eight cases of so-called “Telonomas” of the larynx and neck that have been identified in the files of the Armed Forces Institute of Pathology Otolaryngic Tumor Registry and from the Cytopathology Service at the George Washington University Medical Center. Patients ranged in age from 31 to 72 years. Vocal cord paralysis, treated by Teflon injection, was caused by primary laryngeal carcinoma or metastatic carcinoma (breast, lung) involving the recurrent laryngeal nerve, surgical trauma to the recurrent laryngeal nerve, or postviral neuritis. Subsequent symptomatology, related to extravasation of the Teflon with a resulting “Teflonoma”, included a neck mass or persistent hoarseness. Infrequently, there was associated airway obstruction or voice changes. Diagnosis was made by fine needle aspiration or by excision of the suspicious mass and subsequent identification of a foreign body granulomatous reaction with associated birefringent material. Infrared absorption spectrophotometry identified the foreign material as a fluorocarbon which was further substantiated by scanning electron microscopy and energy dispersive x-ray analysis. Surgical removal of the mass alleviated all symptoms.

Application of the BaTiO_3 beam-fanning optical limiter as an adaptive spatial filter for signal enhancement in pulsed infrared laser-excited photothermal spectroscopy

A method for obtaining a high-contrast visible-light signal from infrared absorption in low-absorbance samples is described. This method is based on a beam-fanning optical limiter in photorefractive BaTiO(3). The resulting signal is not linear but does exhibit an enhanced signal-to-background ratio that is 4 to 6 orders of magnitude better than that of conventional infrared absorption spectrophotometry in the shot-noise limit. A simple model for the beam-fanning, optical-limiter-based, pulsed-laser-excited photothermal spectroscopy detector is found to describe the experimental data adequately. This technique using photothermal spectroscopy detection may have advantages for rapid signal analysis and for two-dimensional visible imaging of infrared absorption.

Derivative Infrared Spectra of Ramie

A derivative technique has been applied to infrared absorption spectrophotometry of ramie in the regions 4000-2500 and 2000-700 cm-1. The second derivative spectra at different scan speeds and differentiator time constants in these regions have been compared with the absorption (zeroth derivative) spectra. The derivative spectra mea sure the slope or curvature of the absorption contours, facilitate to resolve, and detect absorptions that are unresolvable due either to band overlap or low intensity. This method may thus provide more detailed information on the fine structure of cellulose.

Occurrence of carotenoids and sporopollenin in Nanochlorum eucaryotum, a novel marine alga with unusual characteristics

Pigment analysis of Nanochlorum eucaryotum on two strains grown under different gaseous conditions was performed. Air-gasses control cultures did not differ qualitatively with respect to the content of chlorophylls a and b, carotenes α and β, lutein, violaxanthin, neoxanthin and cryptoxanthin in comparison with cultures grown under natural gas. The absolute pigment content per cell increased in cultures grown with natural gas. Growth of N. eucaryotum depends on CO 2 which is present in concentrations up to 2.0 vol% in natural gas. N. eucaryotum cannot utilize methane and is therefore not methylotrophic. In cultures of N. eucaryotum grown with natural gas and in air-gassed cultures under nitrogen deficient conditions the secondary carotenoids canthaxanthin and astaxanthin could be detected. In air-gassed cultures of strain N. eucaryotum Colona the same secondary carotenoids have been found, while secondary carotenoids were never found in strain N. eucaryotum Mainz. Cell walls of N. eucaryotum always contain sporopollenin as confirmed by isolation, elemental analysis, infrared absorption spectrophotometry, acetolysis-resistance and electron microscopy.

Paraffinomas of the Scalp

Four cases of scalp paraffinoma were seen in our clinics within the past year. This unusual condition results from intradermal injection of substances containing paraffin. The presence of paraffin in excised tissue was confirmed by thin-layer chromatography and infrared absorption spectrophotometry. Our patients received their treatments 35 to 42 years ago after responding to radio or newspaper advertisements that promised a cure for baldness. Two patients were initially observed with severe scalp inflammation and two were completely asymptomatic other than having lumpy scalps. Although these cases were readily diagnosed by history, eliminating other possibilities was greatly aided by use of xeroradiography, obviating the need for biopsy in asymptomatic cases.

Silicon Oxidation by Rapid Thermal Processing (RTP)

ABSTRACTSingle crystal silicon wafers have been oxidised by exposure to an oxygen ambient at atmospheric pressure during RTP using an A G Associates Heatpulse 2101 Rapid Thermal Annealer. Wafers of the standard orientations used in silicon device processing <100>, <111> and <110> were studied. Oxidation was carried out in the temperature range 900 to 1250°C for times of RTP from 4 to 25U seconds producing oxides up to 60nm in thickness. Oxidation rates and their orientation and temperature dependence were derived from ellipsometric measurements of oxide thickness. X-ray photoelectron spectroscopy (XPS) and infra-red absorption spectrophotometry were also employed in the oxide characterisation. Preliminary electrical characterisation of the oxides, investigated using MOS C-V analyses, showed that the interface state densities were comparable to those in conventional furnace grown oxides.