Potassium Bromide Disk Research Articles

Investigation and assessment of epoxy resin adhesives using Fourier‐transform infrared spectrometry

AbstractEpoxy resin adhesives are very attractive for many industries, especially in the aerospace and automotive industries because they eliminate heavy connection elements, such as bolts and screws, and reduce the total weight. This study assesses developed epoxy resin adhesives using Fourier‐transform infrared spectrometry. The curing reaction between Epikote 828 epoxy resin and Epikure polyamidoamine curing agent 3090, and the chemical structure of the additives (CAB‐O‐SIL TS‐720) used for rheology control and six different types of fillers (calcite with particle diameters of 700 nm, 5 μm, and 10 μm, coated calcite with a particle diameter of 900 nm, and barite and calcite with a particle diameter of 5 μm) employed in the adhesives are investigated. The Fourier‐transform infrared spectrometry results of the epoxy resin and curing agent demonstrate that 83.5 % epoxy conversion is achieved at a temperature of 25 °C. The chemical composition of the additives with six different types of fillers and 1 %, 3 %, and 5 % additions of CAB‐O‐SIL TS‐720 prepared in both nujol mull and potassium bromide discs is characterized using Fourier‐transform infrared spectrometry. The potassium bromide discs yield higher intensities owing to good packing of cubic particles of potassium bromide with nano particle size CAB‐O‐SIL TS‐720 and all filler types.

Fourier Transform Infrared Spectroscopic, Spectrofluorimetric Assays of Canagliflozin, and Stability-Indicating UV-Spectrophotometric Method for the Simultaneous Determination of Canagliflozin and Metformin.

Green Fourier transform infrared (FTIR) spectroscopy, using potassium bromide (KBr) disc technique, eliminates the consumption of hazardous chemicals. Spectrofluorimetry for drugs that have native fluorescence. Mean centering of ratio spectra (MCRS) analysing overlapped spectra without preliminary separation. Three simple, accurate, and sensitive methods have been developed and validated for the determination of canagliflozin (CANA); one is a stability-indicating method for CANA and metformin (MET) determination. Method A is FTIR using a KBr disc for CANA determination measuring alkyl halide C-F peak area centered on 1230/cm. Method B is spectrofluorimetry using Δ λ = 50 nm synchronous mode at a peak maximum of 291.8 nm for CANA determination using methanol as solvent. Method C is a stability-indicating MCRS method measuring the peak amplitude of CANA and MET at 306.2 and 246.6 nm, respectively, in their mixture with complete CANA oxidation degradation. The linear ranges were: FTIR spectroscopy, 1.50-24.70 μg/mg CANA; spectrofluorimetry, 100.00-600.00 ng/mL CANA; and MCRS, 1.00-25.00 μg/mL CANA and 1-30 μg/mL MET. All results were statistically compared with a reported method: no significant difference was observed. The proposed methods can be used efficiently for routine analysis in QC laboratories. A green FTIR method utilizes only one reagent, KBr. Spectrofluorimetry using a constant wavelength synchronous scan of CANA native fluorescence in nanogram concentrations overcomes conventional excitation/emission spectra drawbacks and proves that the solvent effect in the fluorescence intensity differs according to concentration used. Stability-indicating MCRS determines the studied drugs in bulk, pharmaceutical formulations, accelerated and long-term stability study samples.

Facile determination of ezetemibe and either atorvastatin or simvastatin by Fourier transform infrared spectroscopy

A facile method is proposed herein for simultaneous quantification of ezetemibe, atorvastatin and simvastatin in their commercial tablets. In this study FTIR procedure is described for the simultaneous quantitative determination of two commercial tablet dosage forms composed of (ezetemibe – atorvastatin) and (ezetemibe – simvastatin). For the developed FTIR spectroscopic method, potassium bromide (KBr) disc technique had been used. Specific absorption bands at 514, 1651 and 868 cm−1 were chosen for selective simultaneous analysis of ezetemibe, atorvastatin and simvastatin respectively. In this method, beer’s law was obeyed in the concentration ranges 0.06 –0.40 and 0.12 – 0.30 % w/w in KBr disc for the investigated drugs alone and at their synthetic binary mixtures respectively. Validation study was performed using USP XXV validation and International Conference on Harmonization (ICH) guidelines and resulted in good recoveries ranged from 87.24 to 104.24 % with relative standard deviations less than 8.00 % depicting accuracy, precision, robustness and ruggedness of the developed method. Excellent recoveries were obtained upon application of the developed method to their commercial binary tablets ranged from 92.00 to 100.54 % conforming the suitability of the proposed method for routine analysis at the quality control laboratories.

WITHDRAWN: Formulation & evaluation of β-glycyrrhetinic acid patches with natural bioenhancer

Abstract The main of the present investigation is to prepare and evaluate the patches of 18β-glycyrrhitic acid with synthetic polymers. For reservoir type patch drug and polymer selected were 18 β-glycyrrhetinic acid and carbopol 934. Infrared spectra were recorded using FTIR equipment by the potassium bromide disc method at wavelength range between 4000 and 400 cm−1. 23 factorial design was employed to study the effect of independent variables (gel base, penetration enhancer, rate controlling membrane) on dependent variable (% drug release). The patches were evaluated on the basis of percentage drug content, permeation, skin irritancy test and stability studies. White colour powder, tasteless, odourless. It is freely soluble in ethanol, chloroform. Melting point: 294°C. Infrared absorption spectroscopy (IR) of 18 β- glycyrrhetinic acid showed sharp band at 603, 1380, 1612, 1715 and 1760 cm−1 due to stretching vibration bands of aromatic ring, –CH3, C = C (Cyclic), C = O and –COOH respectively. API (18 β-glycyrrhetinic acid) exhibited peak at 293.9°C accordance with its melting point (292–297°C). CONCLUSION- Reservoir type F4 patch formulated using 5% menthol, 42% ethanol, 50 g carbopol934 gel base with 0.5% piperine as bioenhancer. The present study was one of the few attempts to incorporate phytconstituents in transdermal system and it needs to be further optimized and characterised. These types of herbal formulations possess tremendous potential for the treatment of some of the disease.

Degree of Conversion of Two Universal Adhesives Incorporated with Ascorbic Acid Coated Superparamagnetic Nanoparticles Assessed by FTIRDegree of conversion, universal adhesives, Superparamagnetic Fe3O4nanoparticles, FTIR analysis

Aims: To prepare and characterize a nano-ferro fluid of ascorbic acid coated superparamagnetic Fe3O4nanoparticles and incorporate them into two universal dental adhesives to test their effect on the immediate and 24-hours post-cure Degree of Conversion (DC) in comparison to their control non-incorporated adhesives. Study design: An invitro study.Methods and Material: A colloidal nano ferro fluid of ascorbic acid coated superparamagnetic nanoparticles was prepared and characterized by transmission electron microscopy and incorporated into two universal adhesives. Thirty-two adhesive samples in PotassiumBromide (KBr) discs were prepared for FTIR analysis, and distributed as following, i.e., GI: Eight adhesive samples of non-incorporated All Bond Universal (Control), GII: Eight adhesive samples of 2%-incorporated All Bond Universal, GIII: Eight adhesive samples of non-incorporated Prime&Bond Universal (Control), GIV: Eight adhesive samples of 2%-incorporated Prime&Bond Universal.Equal amount (25μL) of each adhesive was placed on KBr disc, the solvents was evaporated by a gentle steam of air, and then a second KBr disc was mounted over the first one and pressed softly to form a thin adhesive film. Finally, the KBr discs containing the adhesive were placed in the demountable cell holder and mounted into the sample chamber of the FTIR spectrometer. FTIR spectra was then recorded for each adhesive before, immediately after, and 24-hours post-curing to calculate the degree of conversion.Statistical analysis used: Statistical analysis was conducted using independent variable t-test by the IBM-SPSS software version 22.Results: The study results showed good DC values for the incorporated adhesives with no statistically significant differences in the degree of conversion values (i.e. Immediate and 24-hours post-cure) in comparison to control groups for both adhesives. The Prmie&Bond universal (Both control and incorporated) revealed significantly higher DC than All bond universal.Conclusions: Incorporation of ascorbic acid coated Fe3O4nanoparticles at 2% by mass into the universal adhesives resulted in good degreeof polymerization with no significant difference in comparison to their commercial controls.

Positive/Negative Phototropism: Controllable Molecular Actuators with Different Bending Behavior

Herein, a series of molecular actuators based on the crystals of (E)-2-(4-fluorostyryl)benzo[d]oxazole (BOAF4), (E)-2-(2,4-difluorostyryl)benzo[d]oxazole (BOAF24), (E)-2-(4-fluorostyryl)benzo[d]thi...

Synthesis and physical-chemical properties of functional derivatives of 3-benzyl-8-propylxanthinyl-7-acetic acid

Introduction. Synthetic research of new biologically active compounds occupies an important place in modern pharmaceutical science.Thus it is important to develop techniques for the biologically active substances functionalization. Esters and amides take special place among the variety of functional derivatives of organic acids,. These fragments are well-known pharmacophores and could be found in a wide range of drugs. Thus, the nootropic agent pyracetam is 2-oxo-1-pyrolidineacetamide, and is the selective antagonist of β-adrenoreceptores; atenolol is a derivative of benzeneacetamide. Substituted acetamide and ester fragments are also present in the structures of aprofen, spasmolitin, acetylidine and β-lactam cephalosporins and penicillins antibiotics. Aim of our research was the synthetic method development for functional derivatives of 3-benzyl-8-propylxanthinyl-7-acetic acid and the study of their physical-chemical properties. Materials and methods. Melting points were determined using capillary method on DMP (M). 1 Н NMR-spectra were recorded by Varian Mercury VX-200 device (company «Varian» – USA) solvent – (DMSO- d 6 ), internal standard – ТМS. Elemental analysis of obtained compounds was produced on device Elementar Vario L cube. Chemical shifts were reported in ppm (parts per million) values. Infrared (IR) spectra were measured on a Bruker Alpha instrument using a potassium bromide (KBr) disk, scanning from 400 to 4000 cm -1 . Results and discussion. We selected 3-benzyl-8-propylxanthinyl-7-acetic acid as initial compound for our study. For synthesis of hexyl, heptyl, octyl, nonyl, decyl and benzyl esters of 3-benzyl-8-propylxanthinyl-7-acetic acid we used alternative method, that included alkylation of sodium salts of acids with alkyl halogens. Reaction was made at DMF medium by reflux of reagents. Next stage of our research was the synthesis of amides of 3-beznyl-8-propylxanthinyl-7-acetic acid by the reaction of ethyl or propyl esters with butylamine, benzylamine, p-methylbenzylamine or p-fluorobenzylamine. It should be noted that we conducted reaction without solvent in the medium of amine and reagents were not reflux but heated at 80 о С. The structures of all obtained compounds were proved by the elemental analysis, IR- and 1 H NMR-spectroscopy. Conclusions . Obtained results of our work can be used for further search of biological active compounds among functional derivatives of xanthinyl-7-alkanyl acids

Comparison of the anti-duck hepatitis A virus activities of phosphorylated and sulfated Astragalus polysaccharides

Duck hepatitis A virus (DHAV) (Picornaviridae) causes an infectious disease in ducks which results in severe losses in duck industry. However, the proper antiviral supportive drugs for this disease have not been discovered. Polysaccharide is the main ingredient of Astragalus that has been demonstrated to directly and indirectly inhibit RNA of viruses replication. In this study, the antiviral activities of Astragalus polysaccharide (APS) and its derivatives against DHAV were evaluated and compared. APS was modified via the sodium trimetaphosphate and sodium tripolyphosphate (STMP-STPP) method and chlorosulfonic acid-pyridine method to obtain its phosphate (pAPS) and sulfate (sAPS), respectively. The infrared structures of APS, pAPS, and sAPS were analyzed with the potassium bromide disc method. Additionally, the antiviral activities were evaluated with the MTT ((4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide) method invitro and the artificial inoculation method invivo. The clinical therapy effects were evaluated by mortality rate, liver function-related biochemical indicators, and visual changes in pathological anatomy. The anti-DHAV proliferation effects of APS, pAPS, and sAPS on the viral multiplication process in cell and blood were observed with the reverse transcription-polymerase chain reaction method. The results revealed that pAPS inhibited DHAV proliferation more efficiently in the entire process of viral multiplication than APS and sAPS. Moreover, only pAPS significantly improved the survival rate to 33.5% and reduced the DHAV particle titer in the blood as well as liver lesions in clinical trials. The results indicated that pAPS exhibited greater anti-DHAV activity than APS and sAPS both invitro and invivo.

Infrared Absorption Characteristics of Culicoides sonorensis in Relation to Insect Age

Biting midges can transmit diseases that significantly impact livestock in many parts of the world. The age structure of an insect vector population determines its likelihood of transmitting pathogens because the older insects are more likely to be infected than younger ones. Understanding the insect age distribution allows for predictions of their behavior, habitat, vector competence and the vector-borne disease epidemiology. Most insect age grading techniques are laborious and slow, thus we investigated the novel application of midinfrared (MIR) spectroscopy to determine insect age. Female biting midges (Culicoides sonorensis) were anesthetized with chloroform at 1, 4, 7, 10, 13, and 16 days after eclosion. MIR Attenuated Total Reflectance (ATR) spectra of desiccated insects were collected using a Fourier Transform Infrared spectrometer. Transmission spectra of 1, 7, and 13 day old midges were also taken via potassium bromide (KBr) disks prepared with homogenized desiccated insects in each age group. ATR and transmission spectra had identical bands and provide chemical information about the whole insect. The ratio of absorbance of ATR spectra at 1634/1540 cm -1 showed a systematic change with increasing insect age. A similar trend was also observed in the transmission spectra. These absorption bands may be due to the absorbance of chitins and proteins. Therefore, the observed changes in absorption ratios may reflect qualitative or quantitative changes in insect cuticle and/or body proteins in relation to chronological age. When using absorbance data, insects were classified as young (<= 7 days) with 89.2% accuracy, and old with 63.5% accuracy. These results suggest that infrared spectroscopy may be used to develop a rapid method for age grading of midges.

A Comparison of the Performance of Samplers for Respirable Dust in Workplaces and Laboratory Analysis for Respirable Quartz

The divergent sampling techniques for respirable dust and the analyses for crystalline silica are an important area of interest and discussion among industrial occupational hygienists in Europe. The variety of equipment for air sampling, methods and instrumentation can cause differences between results for the analysis of respirable crystalline silica (RCS). In this study, a Workplace Atmosphere Multi-sampler (WAM), developed by Adhesia, was used to compare respirable dust samplers in the workplace. This rotating device enables the comparison of 12 samplers in a workplace in each run. Seven laboratories participated in the comparison, using six different respirable dust samplers [British Cast Iron Research Association (BCIRA) to the Higgins Dewell (HD) design, Dorr Oliver, Casella SIMPEDS, SKC HD with a polycarbonate filter and polyvinylchloride filter, and the CIP10-R). Each laboratory analysed samples supplied by the samplers and reported the total respirable dust concentration and the RCS concentration. The techniques used were X-ray diffraction direct-on-filter, X-ray diffraction with deposition, infrared direct-on-filter, and infrared with potassium bromide (KBr) discs. The experiments were carried out in four different industries (enamel, sand extraction, foundry and brickworks). Generally, the SKC conductive black plastic sampler is oversampled (y = 1.52x + 0.008) and the CIP10 is undersampled (y = 0.74x + 0.068) when compared with the median air concentration. A pair-wise comparison of the different industries using t-tests indicated significant differences (P < 0.05) between the SKC conductive plastic samplers and the other samplers. The same series of statistical calculations were performed for the results obtained for RCS (quartz) and showed significant differences for the CIP10 techniques and the SKC conductive plastic cyclone analyses when using a polyvinylchloride filter.

Degree of Conversion and Antibacterial Activity of Total-Etch Versus Self-Etch Adhesive Systems

Abstract Objectives: This research was conducted to compare the degree of conversion and antibacterial activity of the total-etch (etch-and-rinse) versus self-etch adhesive systems. Materials and methods: Degree of conversion was done using Fourier Transformation Infrared Spectroscopy. Uncured and cured specimens were prepared from each adhesive system and tested using potassium bromide disks. The antibacterial activity of the adhesives was evaluated using agar disc-diffusion test against the following bacteria: Staphylococcus aureus, Streptococcus mutans and Lactobacillus salivarius obtained from soft carious dentin. Paper disks were coated with the tested adhesives and placed in the suitable growth media for each microorganism. The diameters of inhibition zones were measured at three different points. Sizes of inhibition zones were calculated by subtracting the diameter of the specimen from the average of the three measurements of the halo. Results: G-Bond showed higher degree of conversion than that of Stae and Adper Prompt L-Pop adhesives. Adper Prompt L-Pop exhibited the highest antibacterial activity against S. mutans and S. aureus, while Stae exhibited the lowest antibacterial activity against S. mutans and S. aureus. All adhesives failed to demonstrate antibacterial activity against L. salivarius. Conclusions: The tested adhesives showed degree of conversion with various percentages. All adhesives showed antibacterial action against S. aureus and S. mutans. On the other hand, they were failed to inhibit the growth of L. salivarius.

Structural Differences of Proteins between Solution State and Solid State Probed by Attenuated Total Reflection Fourier Transform Infrared Spectroscopy

A Fourier transform infrared (FT-IR) spectroscopic method combined with an attenuated total reflection (ATR) sampling technique has been developed to analyze protein secondary structure in both solid and solution states. The method has been applied to analyze the protein structural differences between solution state and solid state. For alpha-helix dominant proteins, beta-sheet structures increase significantly in the solid state, with significant decrease in alpha-helical structures. For beta-sheet dominant proteins, beta-sheet structures increase only moderately in the solid state. When proteins are re-dissolved in solution, their structures are re-natured to their native structures, as suggested by the fact that their structures in solution state are similar to those determined by X-ray crystallography or other spectroscopic methods in solution state. The ATR sampling technique avoids the high pressure and chemicals that are needed for the conventional potassium bromide (KBr) disc method for solid samples in FT-IR spectroscopy. Our approach from this study demonstrated that ATR sampling is more appropriate for analysis of protein structures in the solid state.

Reflection contributions to the dispersion artefact in FTIR spectra of single biological cells

Fourier transform infrared spectra of a single cell in transflection geometry are seen to vary significantly with position on the cell, showing a distorted derivative-like lineshape in the region of the optically dense nucleus. A similar behaviour is observable in a model system of the protein albumin doped in a potassium bromide disk. It is demonstrated that the spectrum at any point is a weighted sum of the sample reflection and transmission and that the dominance of the reflection spectrum in optically dense regions can account for some of the spectral distortions previously attributed to dispersion artefacts. Rather than being an artefact, the reflection contribution is ever present in transflection spectra and it is further demonstrated that the reflection characteristics can be used for cellular mapping.

Photodegradation of acrylic resins used in the conservation of stone

The photodegradative behaviour of a series of films of acrylic resins, under controlled conditions (RH=50% and T=25°C) has been studied. Films of acrylic resins were applied both on a dolomitic white marble support and on potassium bromide disks. The chemical evolution of the system has been followed by means of FT–IR spectra, HPLC–SEC, colour and water absorption measurements. The main degradation pathway under ultraviolet irradiation is chain scission. The observed rates of photodegradation of the different resins may be related to the type of the ester group and to the presence of the α-methyl group in the main chain.

Rapid Searching Method of Tablet Sample by Micro FT-IR

A rapid searching method of active components in a tablet sample such as benzodiazepines and 3, 4-methylenedioxyamphetamines by micro FT-IR was investigated. The drug was eluted with quite a small volume of dichloromethane and/or benzene from a small piece of tablet sample (generally several hundred μg) to a potassium bromide disk. A portion of the eluate on the disk where the concentration of the drug would be high was measured by micro FT-IR. The obtained spectrum was compared with 480 searchable library data to identify the drug. When the drug contents of a tablet was more than 0.5%, this method was applicable for the tablet sample. Satisfactory results were obtained within about 10min.

Second-derivative FTIR spectra of native celluloses from Valonia and tunicin

The greater resolution afforded by the second-derivative mode has enabled differences previously observed in bands near 3240, 750, and 710 cm −1 in the FTIR spectra of Valonia and tunicin celluloses to be confirmed, and revealed new differences near 2900 and 650 cm −1. These bands are assigned largely to vibrations of groups involved in the system of hydrogen bonds. The remaining bands in the spectra correspond well, which indicates strong similarities in the structures at the conformational level. Differences between the spectra obtained for films and potassium bromide discs are attributed largely to the different orientations of the samples.

Study of the diazoimine/triazole equilibria for substituted thiazoles and thiadiazoles

AbstractSeveral diazomethyl and diazoester substituted thiazoles and thiadiazoles were prepared and their ring/chain equilibria studied by nmr spectroscopy. The diazomethyl derivatives 17a,b,d and 19a exist predominantly or exclusively in the triazole form. Ring‐opening is promoted by introducing an ester group at the diazo function (17c,e, 19b, 21) or by changing thiazoles for thiadiazoles in the following order: thiazole &lt; 1,3,4‐thiadiazole &lt; 1,2,4‐thiadiazole. The diazoimine/triazole equilibria are also shifted towards the diazo form by raising the temperature and by using less polar solvents in the order: dimethyl sulfoxide &lt; acetonitrile &lt; chloroform &lt; benzene. The ir spectra (potassium bromide discs) of the compounds indicate that they all, except 21, exist in the crystalline state in the triazole form.

Analysis of aliphatic and phenolic carboxylic acids by capillary supercritical fluid chromatography-Fourier-transform infrared microspectrometry

A mobile phase elimination interface and a microscope accessory are used to combine capillary supercritical fluid chromatography with Fourier-transform infrared spectrometry for analyzing carboxylic acids. Separations of a mixture of oligomers prepared by a self-condensation polymerization of 12-hydroxystearic acid and of a mixture of 16 phenolic carboxylic acids are achieved by using a well-deactivated fused-silica capillary column coated with an oligoethyleneoxide substituted methylpolysiloxane (glyme) stationary phase and carbon dioxide as the mobile phase. Components requiring identification are deposited, with elimination of the carbon dioxide, onto potassium bromide discs as compact spots, from the end of a heated restrictor, which is attached at the end of the column. Unique spectroscopic information is obtaned by positioning the spots in the microscope and measuring their infrared spectra. Phenolic acids are unambiguously identified and the degree of polymerization of oligomers in the 12-hydroxysteric acid reaction mixture is indicated from the ratio of ester carbonyl to acid carbonyl absorptions.

Characterization and identification of substances isolated from dialyzer extracts.

The organic phase of dialyzer dried extracts obtained from Cuprophan hollow fiber and polyacrylonitrile AN 69 parallel-plate dialyzers, all sterilized by ethylene oxide, were submitted to light and polarized light microscopy, infrared (IR) spectrophotometry, and gas chromatography coupled with mass spectrometry. Colorless polygonal (approximately 5 X 20 micron) and needle-like (approximately 3 X 50 micron) crystals were found in great quantity on microscopy examination. IR spectrophotometry of the crystals embedded in potassium bromide disc showed specific spectra in the 1400-800 cm-1 wave number range and typical peaks on wave number assigned for hydroxy or amine (3420 cm-1), aromatic hydrogen (3060 cm-1), methyl, methylenic, or methenyl (2960-2860 cm-1), and carbonyl (1715 cm-1) groups can be demonstrated. Seven peaks were detected on gas chromatography of the organic solution containing crystals. Fatty acids and undefined compounds could originate from the dialyzer. Phtalates may leach from blood tubing, used in the rinsing procedure, and BHT is a stabilizer of ethyl ether used as solvent. These compounds could also originate from the dialyzer since phtalates are widely used as a plasticizer and BHT an antioxidant for various polymers.

Supercritical fluid extraction / capillary supercritical fluid chromatography / Fourier transform infrared microspectrometry of polycyclic aromatic compounds in a coal tar pitch

AbstractThe combination of supercritical fluid extraction, high resolution capillary supercritical fluid chromatography, and Fourier transform infrared microspectrometry is described for the separation and identification of polycyclic aromatic hydrocarbons in a coal tar pitch. The variable solvating power of the supercritical fluid was utilized to selectively fractionate the sample. The fluid extract was decompressed through a frit restrictor into the sample cavity of a cooled microvalve injector, where the analytes were deposited and concentrated for subsequent chromatographic analysis. Several of the analytes separated in the chromatograph were collected on a potassium bromide disc at a solvent elimination inter‐face for subsequent infrared analysis involving the use of an infra‐red microscope accessory. The spectra obtained show the power of this detection technique for distinguishing between isomers.