Potassium Bromide Pellet Research Articles

Classification of asbestos and their nonasbestiform analogues using FTIR and multivariate data analysis

This study presents a possible application of Fourier transform infrared (FTIR) spectrometry and multivariate data analysis, principal component analysis (PCA), and partial least squares-discriminant analysis (PLS-DA) for classifying asbestos and their nonasbestiform analogues. The objectives of the study are: 1) to classify six regulated asbestos types and 2) to classify between asbestos types and their nonasbestiform analogues. The respirable fraction of six regulated asbestos types and their nonasbestiform analogues were prepared in potassium bromide pellets and collected on polyvinyl chloride membrane filters for FTIR measurement. Both PCA and PLS-DA classified asbestos types and their nonasbestiform analogues on the score plots showed a very distinct clustering of samples between the serpentine (chrysotile) and amphibole groups. The PLS-DA model provided ∼95% correct prediction with a single asbestos type in the sample, although it did not provide all correct predictions for all the challenge samples due to their inherent complexity and the limited sample number. Further studies are necessary for a better prediction level in real samples and standardization of sampling and analysis procedures.

Using potassium bromide pellets and optical spectroscopy to assess the photodimerization of two trans-(trifluoromethyl)-cinnamic acid compounds

Solid state photoreactions are an attractive route to produce special isomers due to the crystal packing of the starting molecules. We use powder samples pressed into potassium bromide pellets to investigate photoreactions with optical spectroscopy.

Seminal infrared-based chemometric analysis of oxygen-bearing structural groups in vitrain samples from ten successive coal seams (Sydney Coalfield, Canada)

Reported are seminal results of a systematic application of infrared spectrometry to a succession of coal seams in a Carboniferous basin from Sydney Coalfield, Nova Scotia, Canada. Fifty-four lithotypic vitrain samples from ten successive coal seams were analyzed by solid-state (potassium-bromide pellet method) Fourier transform infrared spectroscopy and evaluated using principal-component analysis to explore chemical fingerprints of vitrain structural-group contents and distributions. At this level of sampling, the 3D principal-component analysis and ANOVA tests identified chemical structural-group changes related to relatively low contents of aliphatic and oxygen-bearing compounds. These probably confirm, for data represented by “younger” seams, the moderate thermal histories (0.75–0.90 Ro %) from which minimal diagenetic alterations are inferred in the preservation of fossils in the roof rocks of the coal seams. It is concluded that, throughout the lithostratigraphic column, the continual vertical changes in vitrain structural-group composition are related to some changes in the species diversity of the associated macroflora that filled niches in the peat-producing lower flood plains.

EXTRACTION, QUANTIFICATION, AND FTIR CHARACTERIZATION OF BARK TANNINS OF FOUR FOREST SPECIES GROWN IN NORTHEAST BRAZIL

ABSTRACT Condensed tannins are chemical compounds derived from the secondary metabolism of plants. They are of particular interest due to their broad range of technological uses and applications. The objective of this study was to extract, quantify, and characterize by Fourier-transform infrared spectroscopy (FTIR) the bark tannins of four forest species grown in Northeast Brazil: Acacia mangium, Azadirachta indica, Mimosa tenuiflora, and Mimosa caesalpiniifolia. Bark samples were collected from 5 trees of each species grown in a five-year-old forest stand. Samples were collected, grounded, and submitted to extraction with hot water, then measured to determine total solids content (TSC), Stiasny number (SN), and condensed tannins content (CTC). FTIR spectra were acquired from tannin samples fixed in potassium bromide pellets. Among the four species, M. tenuiflora presented the highest CTC, equal to 23.4%, and the purest crude hot-water extract with SN of 91.27%. Based on FTIR characterization, tannins from M. caesalpiniifolia, A. indica, and A. mangium barks were classified as proanthocyanidins and those from M. tenuiflora bark as prodelphinidins.

Fourier-Transform Infrared (FTIR) spectroscopy analysis of seven wisconsin biosolids

Our research explores the use of Fourier-transform infrared (FTIR) spectroscopy to better understand the phosphorus (P) characteristics of biosolids and how these characteristics can affect agricultural production. Our question was whether FTIR spectra can differentiate between the organic and inorganic species of phosphorus in biosolids by showing shifts in the peaks that indicate species of phosphorus. We obtained biosolids from five Wisconsin wastewater treatment plants (Madison, Delafield, East Troy, Mukwonago, and Fort Atkinson). From the Madison location, we obtained several samples from different parts of the treatment process — cake, final liquid (labeled as Metrogro), and composted biosolids. We compared the FTIR spectra from these samples to P standards, aiming to identify the dominant P species in each biosolid. We employed several FTIR methods: attenuated total reflectance (ATR), sodium chloride (NaCl) salt plates with mineral oil, and pressed potassium bromide (KBr) pellets. We found that the FTIR method that best shows P species differences in the biosolids was the pressed KBr pellet method. Additionally, the P standards indicated two critical wavelength regions in which the inorganic species’ FTIR peaks are shifted to a higher wavenumber than those of the organic species. This work indicated that we can use KBr pellet FTIR as a simple and rapid method to start characterizing P species in biosolids. These research findings could provide farmers useful information about P availability to crops and risk of P loss in runoff when applying biosolids to their fields.

Effect of Different Resin Thickness on Some Physical Properties of Sonic Fill Versus Bulk Fill Resin Composite

Purpose: This study evaluated the effect of resin thickness from both {Sonic Fill resin composite (SF)& Tetric N Ceram Bulk Fill resin composite (TNB)} on polymerization shrinkage strains, depth of cure and degree of conversion. Material and Methods: A total of 70 specimens were prepared and Polymerization shrinkage strains were measured by strain gauge foil connected to the computer software program which gave the results. Depth of cure (DOC) was measured by Vickers microhardness tester applying a 50g load through a Vickers indenter with a dwell time of 10s and expressed as mean of hardness ratio. Degree of conversion (DC%) was measured using Fourier transform infrared spectroscopy by potassium bromide pellet technique. All recorded data were presented, tabulated and statistically analyzed. Results: the strains resulted from both materials increased with increasing the thickness of the specimens from 2mm to 4mm but decreased at 6mm. There was a statistically significant increase in depth of cure and degree of conversion in SF than in TNB at all specimen thickness. Conclusions: Bulk fill resin composite in thickness more than 4mm affect the physical properties; degree of conversion, depth of cure and polymerization shrinkage.

Rapid determination of styrene-butadiene-styrene (SBS) content in modified asphalt based on Fourier transform infrared (FTIR) spectrometer and linear regression analysis

A rapid method predicting SBS content in SBS modified asphalt was proposed. Portable Fourier transform infrared (FTIR) spectrometer was used to obtain infrared spectra of original asphalt, SBS modifier, and SBS modified asphalt. Two test methods and two software programs were applied for processing data in infrared spectra. Absorption peak at the wavenumber of 966 cm−1 was selected as the characteristic peak of the SBS modified asphalt, and absorption peaks at 1377 cm−1 and 813 cm−1 were used as characteristic peaks of original asphalt. Linear regression was conducted to establish the relationship between SBS content and characteristic peaks parameters. Finally, a prediction method was developed and its accuracy, repeatability, and applicability were verified. Results show that potassium bromide pellet method is better for FTIR testing. Characteristic peak height (or area) ratio of SBS and original asphalt linearly changed with SBS content. Peak area ratio has better correlation with SBS content.

Spectral selectivity of multiple nanoparticles doped thin films.

Microscopic thin film doped with different species of nanoparticles displays a unique wavelength selectivity in the context of micro/nanoscale radiative heat transfer. We propose a methodology to shift, broaden, and suppress the thermal radiative selectivity in the desired wavelength ranges. Measured transmittance spectra of potassium bromide pellet doped with a single species of nanoparticles are compared with the theoretical prediction using refractive indices that are extracted by refitting transmittance spectra curve according to the Lorentz-Drude model. For a media doped with more than two species of nanoparticles, a successive effective dielectric function using the refitted complex refractive indices and Maxwell Garnett theory is used to evaluate the thermal radiative selectivity of the composites. It has been confirmed theoretically and experimentally that the wavelength selectivity in the transmittance spectra can be influenced by choosing proper species of materials and varying volume fractions of multiple nanoparticles. This work has shed light on the design and fabrication of novel composites doped with multiple particles for applications such as thermophotovoltaics, radiative cooling, and biosensing.

Synthesis, Characterization and Anthelmentic Activity of Indole Derivatives

Indole is a planar molecule with a conjugated system of 10 p electrons. It exists in resonance form with resonance energy of 47-49 K cal/mole. It is a very weak base with Pka value 3.63. In structure a, b, and d the benzenoid 6-p system is preserved. The chemical structures of the synthesized compounds were established on the basis of physical, chemical, analytical data. The purification of the compounds was carried by purification methods like recrystallization. Physical constant like melting point, boiling point etc, of the new compounds were determined. All the intermediates and final synthesized products were inspected visually for physical appearance. It was physically characterized on the basis of organoleptic properties like color, odor and taste. This determination was obtained using a digital capillary melting point apparatus (Cambell Electronics, Bombay, India) by capillary fusion method. All the synthesized materials were further identified and confirmed by Thin Layer Chromatographic (TLC). UV/Visible spectra enables us o study the absorption pattern of the molecule and determination of lmax which is useful for the quantitative estimation of the compound. The IR spectrum of all the synthesized materials was recorded, which showed stretching and bending vibration levels of molecules in potassium bromide pellet by FTIR Spectrophotometer. The synthesized compounds were screened for Anthelmintic activity by using Mathew et al method and Indian adult earthworms (Pheretima Posthuma). All substituted quinoxaline compounds have been screened for their anthelmentic activity. From the screening results it was observed that the presence of electron withdrawing group made the substituted quinoxaline compounds to exhibit moderate to significant anthelmentic activity in comparison to standard drug albendazole. Compound QX1 and QX5 exhibited promising anthelmentic activity. However other two compounds (QX2 & QX4) of the series also exhibited moderate to weak activity against the Pheritma phosthuma. Keywords: Pheritma phosthuma, Indole, Anthelmentic activity.

Development and Evaluation of Amoxicillin Loaded Carbopol 934P Mucoadhesive Microcapsules for Sustained Drug Release for H. pylori Treatment

Amoxicillin (α-amino-p-hydroxybenzyl-penicillin) is a semi-synthetic, orally absorbed and widely prescribed β-lactam antibiotic. It is now widely used for eradication of gastric Helicobacter pylori infection combined with a second antibiotic and an acid‐suppressing agent despite its short elimination half-life of one hour. The purpose of this study was to develop and evaluate amoxicillin loaded carbopol 934P mucoadhesive microcapsules for sustained drug release at the gastric mucosa to prolong the residence time of dosage form in the stomach and to achieve controlled drug release for more effective H. pylori eradication. Amoxicillin mucoadhesive microcapsules were formulated by ion gelation technique using 32 factorial designs. A 32 full factorial design was used to derive the statistical equation, ANOVA analysis, contour plots and 3D response surface plots. FT- IR (4000 cm-1- 450 cm-1) analysis of amoxicillin and with polymers was performed by using potassium bromide pellet method. Different polymer ratios of carbopol 934P and sodium alginate were used to formulate by nine formulations (F1 to F9) amoxicillin mucoadhesive microcapsules. The prepared formulations were characterized by determining their percentage of yield, particle size, percentage of entrapment efficiency, swelling index, percentage of mucoadhesion and percentage of drug release. Amoxicillin and used polymers are found to be compatible with no interaction reported by FTIR analysis. The optimized formulation (F9) exhibited a high drug entrapment efficiency of 96.04±0.03%, particle size of 847.2518±0.06 μm, yield of 98.86±0.01%, swelling index of 120.09±0.06%, and mucoadhesion of 67.00±0.02 after 8 h. A successful sustained drug release was achieved for more than 14 h. In-vitro dissolution test for optimized formulation (F9) demonstrated a slower release behavior in 0.1N hydrochloric acid followed by linear release profile in pH 7.4 phosphate buffer. The drug-to-polymer-to-polymer ratio had a more significant effect on the dependent variables. The release kinetic study of optimized formulation (F9) displayed a good fitting with zero order behavior and Korsmeyer-Peppas model has confirmed a non-Fickian release. The developed mucoadhesive amoxicillin microcapsules were observed to have adhered strongly with gastric mucosa with approximately 14 h of prolonged stay expecting improved bioavailability and reduced dosing frequency and subsequently improving patient’s compliance. The concentration of carbopol 934P and sodium alginate had highly significant effects on depended variables. The present study concludes that amoxicillin mucoadhesive microcapsules can be effectively used for the more effective treatment of H. pylori infection.

Fourier-Transform Infrared (FTIR) Spectroscopy Transmission Technique for Analysis of Characteristic Infrared Bands of Peptide Linkage using Dried Proteins

Protein activity is well dependent on its conformational structure and thus secondary structure prediction and determination of proteins are vital requirements. FTIR is rapidly coming up for protein structural studies, as an alternative to circular dichroism. However, FTIR spectra are primarily recorded using protein samples prepared in water, organic solvents, deuterium oxide, and membranes. FTIR spectra are thus dominated by the solvent spectrum and subtraction of the solvent spectrum introduces severe spectral distortions. In aqueous protein solutions, a strong water signal overlaps amide I bands (C=O stretching; 1700-1600 cm−1), thus masking most of the protein secondary structure information. Further, most of the purified proteins including protein drug formulations are more stable in the solid state than in the liquid state. Hence there is a need to explore the use of FTIR for various physical states of proteins. In the present study, we showed that protein secondary structure can be analyzed in a dried state; using potassium bromide (KBr) pellet method for dried known proteins (bovine serum albumin, proteinase K, fibrinogen etc). KBr pellet method gave excellent spectra for all the used dried proteins; shown by the appearance of characteristic infrared bands of peptide linkage (Amide A, B, I-VI) without much interference from water, buffers, stabilizing factors, co-factors etc. We also found that KBr pellet method can analyze a range of protein types; globular to fibrous. Thus KBr method is a great tool for prediction/determination of the secondary structure of unknown proteins and quality control of solid-state protein drug formulations.

FTIR Spectrophotometry as a Green Tool for Quantitative Analysis of Drugs: Practical Application to Amoxicillin

Amoxicillin is an antimicrobial agent that belongs to the penicillin compounds. Its bactericidal action causes a destruction of the cell wall of bacteria. It is widely used in clinical practice, and it belongs to the Brazilian National List of Essential Drugs (RENAME). In literature, there are some green analytical methods for the amoxicillin analysis; however, none of them is focused on its quantification in capsules. Therefore, the aim of this study was to validate an environmentally friendly analytical method for the analysis of this antimicrobial action in capsules, using spectrophotometry in the mid-infrared region. The analyses were performed in the spectral range of 1815–1736 cm−1, and the samples were analyzed as potassium bromide pellets. The method was validated according to the ICH guidelines and Brazilian legislation. Linearity, selectivity, precision, accuracy, and robustness were evaluated and showed adequate results for method validation, in a concentration range of 0.5–1.5 mg/pellet. Thus, it is concluded that the validated spectrophotometric method is able to quantify amoxicillin in capsules. In addition, it is a fast, economical, and environmentally friendly method, since it does not use organic solvents, and it can be used for quality control of routine analysis of this drug.

An extended excited-state intramolecular proton transfer (ESIPT) emitter for random lasing applications.

An original molecular fluorophore displaying single keto (K*) excited-state intramolecular proton transfer (ESIPT) emission is presented in this article. Substitution at the 3 and 5 positions of the phenol ring of a 2-(2'-hydroxyphenylbenzoxazole) (HBO) dye by triethylsilyl-ethynyl fragments leads to a drastic enhancement of fluorescence in the solution-state as compared to unsubstituted analogues. This intense fluorescence emission is also retained in a protic solvent like ethanol and in the solid-state as embedded in a potassium bromide pellet or as 1% doped in a poly(methyl methacrylate) (PMMA) film. The experimental optical properties were confirmed by ab initio calculations. Random lasing (RL) studies performed on this ESIPT emitter show the presence of stimulated emission occurring above the threshold level of pumping energy density (ρth ≈ 300 μJ cm-2) in the PMMA matrix. To the best of our knowledge, this study constitutes the first observation of RL based on ESIPT fluorescence.

The effect of incorporating different concentrations of chlorhexidine digluconate on the degree of conversion of an experimental adhesive resin.

BackgroundThe aim of this study was to evaluate the effect of chlorhexidine digluconate incorporation on the degree of conversion of an experimental adhesive resin.Material and MethodsThe experimental resin was prepared from 70 wt% bisphenol A glycerolate dimethacrylate, 30 wt% hydroxyethyl methacrylate, silanized SiO2 nanofillers, 0.5% of camphorquinone and ethyl 4-dimethylaminebenzoate (binary photo-initiator system). Five chlorhexidine digluconate concentrations (0, 0.5, 1, 2 and 4 wt%) were then incorporated into the experimental resin. Thirty Potassium Bromide pellets were prepared then divided into six groups (n=5/group), repre¬senting the tested adhesive resins (Single Bond 2, 0, 0.5, 1, 2 and 4 wt% chlohexidine-incorporated experimental adhesive resins), that were applied to the pellets without light-curing (uncured specimens). Another 30 pellets were prepared and treated with the previous materials then light-cured using LED light-curing device (cured specimens). Degree of conversion of the uncured and the cured specimens were evaluated using FTIR analysis.ResultsAdper Single Bond 2 showed the highest degree of conversion mean values followed by 0.5 wt% chlorhexidine concentration then 2 wt% followed by 4 wt% then 1 wt% concentrations, while 0 wt% concentration showed the lowest mean values.ConclusionsChlorhexidine digluconate had slight significant influence on the efficiency of polymerization of the experimental adhesive resin. Key words:Chlorhexidine digluconate, different concentrations, degree of conversion, experimental adhesive resin.

IR spectroscopy of organic co-crystals of 4-nitrophenol with 2-aminopyridine and 2,6-diaminopyridine

IR spectra of co-crystals based on 4-nitrophenol with derivatives of aminopyridines are studied within the range of 450–4500 cm–1. As samples, 2-aminopyridine–4-nitrophenol and 2,6-diaminopyridine–4-nitrophenol are chosen. The samples are prepared by two methods, i.e., by pressing of potassium bromide pellets and by coating of fluorite with a mixture of the sample with vaseline oil. Comparative analysis shows that the spectra of co-crystals differ from the spectra of mixtures of their components. It is found that some vibrations in the spectra correspond to vibrations of aminogroups probably involved in bonding between components in co-crystals, which confirms the formation of co-crystals.

Effect of polymerization protocol on the degree of conversion of photo- and dual-polymerized self-etch adhesives

This study investigated the effect of different polymerization protocols on the degree of conversion (DC%) of various photo-polymerized and dual-polymerized self-etch adhesive resins. Five different photo-polymerized (All-Bond Universal, Bisco; G-ænial Bond, GC; Futurabond M+ LC, VOCO; Single Bond Universal LC, 3M ESPE and Peak Universal Bond, Ultradent) and four dual-polymerized self-etch adhesives (Futurabond U, VOCO; Gradia Core SE, GC; Futurabond M+ DC, VOCO and Single Bond Universal DC, 3 M ESPE) were tested. All adhesives were applied on potassium bromide pellets (KBr) following the manufacturer’s instructions. The KBr pellets were divided into 10 experimental groups for the photo-polymerized adhesives and 12 experimental groups for the dual-polymerized adhesives according to the two levels of the study, Level 1: polymerization protocol and Level 2: adhesive system. For the photo-polymerized adhesives, the adhesives were polymerized either at 1 or 10 mm from the KBr pellets. For the photo-polymerized adhesives, the adhesives were photo-polymerized either at 1 or 10 mm distance or polymerized chemically. The DC% of the unpolymerized and polymerized adhesives was assessed using Fourier transform infrared spectroscopy. Data were analyzed using two-way ANOVA to evaluate the effect of polymerization protocol, adhesive system, and their interaction on the DC% of the self-etch adhesives. For the photo-polymerized and dual-polymerized adhesives, one-way ANOVA and Tukey HSD post hoc test was used to evaluate the effect of adhesive system within each polymerization protocol and the effect of polymerization protocol within each adhesive for the dual-polymerized adhesives (p = 0.05). Student t-test was used to compare the effect of polymerization distances within each photo-polymerized adhesive. For both photo- and dual-polymerized adhesives, the polymerization protocol and adhesive system had a significant effect on the DC (p = 0.000). The interaction between the two factors (polymerization protocol and adhesive system) revealed also a significant effect on the DC% of the different adhesives (p = 0.000). Polymerization distance of 1 mm showed significantly higher DC% compared to 10 mm distance. When the dual-polymerized adhesives were left to set chemically, they showed the lowest DC% among all polymerization protocols. DC varied depending on the chemical composition of the self-etch adhesives. The tip of the polymerization device should be positioned as close as possible to the surface to achieve higher DC% of the tested adhesives. Photo-polymerization of the dual-polymerized self-etch adhesives is a mandatory step to improve their DC.

Method of Infrared Spectra Registration of Activated Carbons in Potassium Bromide Pellets

Method of Infrared Spectra Registration of Activated Carbons in Potassium Bromide Pellets

A Method to Obtain the Absorption Coefficient Spectrum of Single Grain Coal in the Aliphatic C–H Stretching Region Using Infrared Transflection Microspectroscopy

A method was developed to obtain the absorption coefficient spectrum of a grain of coal (as small as 10(-7)) in the region of aliphatic and aromatic C-H stretching bands (2700-3200 cm(-1)) using infrared transflection microspectroscopy. In this method, the complex refractive index n - ik was determined using an optimization algorithm with the Kramers-Kronig transform so that the calculated transflection spectrum from the Fresnel equation corresponded to the measured one. The obtained absorption coefficients were compared with the bulk values determined from the potassium bromide (KBr) pellet measurement method.

Analysis of the Chemical Composition of Urinary Calculi using Fourier Transform Infrared Spectroscopy: A Preliminary Study

ABSTRACT Background The etiology of primary and recurrent stone formation in the urinary tract remains obscure in spite of intensive research. The formation of renal calculi is a multifactorial disorder resulting from the combined influence of epidemiological, biochemical and genetic risk factors which disturb the lithogenous salt profile in the body. Materials and methods In the present study, 52 stone samples have been analyzed for their stone composition by Fourier transform infrared spectroscopy (FTIR). The samples were made in a potassium bromide pellet and analyzed to identify the stone components. Results Stone formation was more prevalent in males and the incidence increased with age. Majority of stones were oxalate and mixed stones. The components of mixed stones were identified by spectrum analysis. Conclusion Specific dietary factors can affect the urinary composition and supersaturation, which in turn, can affect the process of crystallization and stone formation. The same chemical components may crystallize in different forms during stone formation. Hence, proper analysis has to identify not only the molecular species present in the calculus, but also the crystalline form. So, quantitative evaluation of all components of the calculi is necessary for effective prevention or reduction of stone recurrences. How to cite this article Bhattacharyya S, Sharma G, Mandal AK, Singh SK. Analysis of the Chemical Composition of Urinary Calculi using Fourier Transform Infrared Spectroscopy: A Preliminary Study. J Postgrad Med Edu Res 2014;48(3):128-131.

Crosslinked polysulfone obtained by Wittig-Horner reaction in biphase system

Phase transfer catalyzed reactions are often more easily and cheaply performed than conventional method and they are therefore of particular interest. A polysulfone functionalized with phosphonate (2-PSF) was prepared under phase transfer catalysis (PTC) conditions, and it was evaluated by spectrometric method (Fourier transform infrared spectroscopy, using potassium bromide (KBr) pellet). The phosphorus content of the modified polysulfone was determined, and it was used for the determination the fraction of repeating units functionalized with phosphonate groups. The modified polysulfone contains 1.40 mmol phosphonate/g polysulfone. Polysulfone functionalized with phosphonate groups and polysulfone functionalized with aldehyde groups (3-PSF) were used in Wittig-Horner reaction, to introduce double bonds on polymer and to obtain crosslinked polysulfone (4-PSF). The reactions were performed using PTC method, solid-liquid (potassium carbonate (K2CO3), tetrahydrofuran (THF), tetraethylammonium iodide (TEAI)) system. The structure of polysulfone functionalized with phosphonate groups and polysulfone functionalized with aldehyde group were confirmed by 1H-, 13C-, and 31P-nuclear magnetic resonance (NMR). The peak for phosphorus in PSF-phosphonate appears in 31P NMR spectrum as a singlet at 25.712 ppm. The thermal properties of aldehyde, phosphonate, and crosslinked polysulfone were studied by thermogravimetric analysis (TG) and differential thermogravimetric analysis (DTG). Scanning electron microscopy images for polysulfone functionalized with phosphonate and crosslinked polysulfone are in concordance with nitrogen (N2) adsorption-desorption isotherms.POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers