Showing papers in "American Journal of Analytical Chemistry in 2017"

Traceability of Active Compounds of Essential Oils in Antimicrobial Food Packaging Using a Chemometric Method by ATR-FTIR

Abstract: A simple and rapid Fourier Transform infrared (FTIR) spectroscopy method was developed to determine the main essential oil components (carvacrol, thymol and p-cymene) in the antimicrobial LDPE films incorporated with oregano (Origanum vulgare) and thyme (Thymus vulgaris) essential oils. The ATR-FTIR spectrum of pure active components (carvacrol, thymol and p-cymene) was characterized, and the ranges between 1125 cm-1 - 1095 cm-1, 1170 cm-1 - 1140 cm-1 and 1050 cm-1 - 1017 cm-1 were respectively used for quantitative estimation. Partial least square (PLS) analysis was used for quantitative analysis. FTIR spectroscopy with chemometrics, using the PLS-1st derivative spectra, could predict the content of active compounds accurate to an r2 greater than 0.99 and a standard error of prediction (SEP) less than 0.7. The developed method was successfully applied to predict the concentration of active compounds: carvacrol, thymol and p-cymene in oregano and thyme essential oils with results compared to those of the GC-MS method. The described non-destructive method can be applied in the industry instead of extraction, distillation and blend processes of the mentioned essential oils and can be extended to detect the content of carvacrol, thymol and p-cymene in active packaging and other commercial products.

Evaluation of Standards and Interfering Compounds in the Determination of Phenolics by Folin-Ciocalteu Assay Method for Effective Bioprocessing of Biomass

Abstract: Folin Ciocalteu (F-C) assay is the most widely used and convenient method to determine the total phenolics content in foods, herbs, and other plant extracts. Different phenolics standards such as gallic acid, ferulic acid, chlorogenic acid, catechol, and vanillic acid have been used for calibration curves in this assay method. Comparison of these standards, in single or combination of two or more, for more accurate determination of phenolics has not been reported so far. This study tested five single phenolics and seven combinations of mixed phenolic standards to evaluate the optimal standards for F-C method. The different standards were tested to calculate the phenolic content in three known test solutions. We also evaluated interference effect of various compounds in phenolics estimation by F-C method that is usually present in the lignocellulosic biomass-derived sugar solution, and in food products along with phenolics. Finally, the optimal standards with five phenolics were used for the determination of phenolics in alkali pretreated biomass extract. The results indicated that gallic acid was the best standard among the single phenolic compounds and five phenolic compounds solution was the best standard among the mixed phenolic solutions. The presence of glucose, HMF, furfural, and vitamin-B12 did not interfere in phenolic determination; whereas ascorbic acid, tyrosine, formic acid, and acetic acid strongly interfered the results. The results also showed that biomass pelleting process did not affect the generation of phenolics in alkali pretreatment extract.

Photodegradation of Binary Azo Dyes Using Core-Shell Fe3O4/SiO2/TiO2 Nanospheres

Abstract: Photodegradation has emerged as an environmentally friendly method of decomposing harmful dyes in wastewater. In this study, core-shell Fe3O4/SiO2/ TiO2 nanospheres with magnetic cores were obtained from synthesised magnetic Fe3O4 nanoparticles through the precipitation method, the surface of the magnetic Fe3O4 nanoparticles was coated with a silica (SiO2) layer by hydrolysis of tetramethoxysilane (TMOS) as a silica source, and finally, Fe3O4/SiO2 nanospheres were coated with titanium (TiO2) layer using tetrabutyltitanate (TBT) as a precursor through the sol-gel process. The morphology and structure of the prepared materials were characterised by X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), X-ray energy dispersive spectrometry (EDAX), Fourier transform infrared spectroscopy (FT-IR), and atomic force microscopy (AFM). The photocatalytic activities of the prepared core-shell nanospheres were studied using binary azo dyes, namely methyl orange (anionic dye, MO) and methylene blue (cationic dye, MB) in aqueous solution under UV light irradiation (365 nm), and UV-Vis spectrophotometer was utilised to monitor the amount of each dye in the mixture. It was found that 90.2% and 100% of binary MO and MB were removed for 5 h, respectively. The results revealed that the efficiency of the photocatalytic degradation of the core-shell nanospheres was not degreased after five runs that can be used as recyclable photocatalysts. The results show that the performance of the prepared core-shell nanospheres was better than that of commercial TiO2 nanoparticles. Moreover, the magnetic separation properties of the core-shell Fe3O4/SiO2/TiO2 nanospheres can enable the prepared materials to have wider application prospects.

Influence of Mn Doping on the Sensing Properties of SnO 2 Nanobelt to Ethanol

Abstract: Mn doped SnO2 nanobelts (Mn:SnO2 NBs) and pure SnO2 nanobelts (SnO2 NBs) were synthesized by thermal evaporation technique at 1355°C with Ar carrier gas (25 sccm, 150 Torr). The SEM, EDS, XRD, TEM, HRTEM, SAED, XPS, UV-Vis techniques were used to characterize the attained samples. The band gap of Mn doped SnO2 NBs by UV-Vis was measured to be 3.43 eV at room temperature, lower than that of the pure counterpart with ~3.66 eV. Mn:SnO2 NB and pure SnO2 NB sensors were developed. It is found that Mn:SnO2 NB device exhibits a higher sensitivity with 62.12% to 100 ppm of ethanol at 210°C, which is the highest sensitivity among the three tested VOC gases (ethanol, ethanediol, and acetone). The theoretical detection limit for ethanol of the sensor is 1.1 ppm. The higher response is related to the selective catalysis of the doped Mn ions.

Salting-Out Assisted Liquid-Liquid Extraction Combined with HPLC for Quantitative Extraction of Trace Multiclass Pesticide Residues from Environmental Waters

Abstract: In this study, salting-out assisted liquid-liquid extraction combined with high performance liquid chromatography diode array detector (SALLE-HPLC-DAD) method was developed and validated for simultaneous analysis of carbaryl, atrazine, propazine, chlorothalonil, dimethametryn and terbutryn in environmental water samples. Parameters affecting the extraction efficiency such as type and volume of extraction solvent, sample volume, salt type and amount, centrifugation speed and time, and sample pH were optimized. Under the optimum extraction conditions the method was linear over the range of 10 - 100 μg/L (carbaryl), 8 - 100 μg/L (atarzine), 7 - 100 μg/L (propazine) and 9 - 100 μg/L (chlorothalonil, terbutryn and dimethametryn) with correlation coefficients (R2) between 0.99 and 0.999. Limits of detection and quantification ranged from 2.0 to 2.8 μg/L and 6.7 to 9.5 μg/L, respectively. The extraction recoveries obtained for ground, lake and river waters were in a range of 75.5% to 106.6%, with the intra-day and inter-day relative standard deviation lower than 3.4% for all the target analytes. All of the target analytes were not detected in these samples. Therefore, the proposed SALLE-HPLC-DAD method is simple, rapid, cheap and environmentally friendly for the determination of the aforementioned herbicides, insecticide and fungicide residues in environmental water samples.

FTIR-ATR and FT-Raman Spectroscopy for Biochemical Changes in Oral Tissue

Abstract: Nowadays, biomedicine development is caused by the necessity of fast premalignant and malignant diagnosis. In the case of cancer, it is important to identify degree of tumor’s malice. We investigated the differences of Fourier Transform Infrared-Attenuated Total Reflection (FTIR-ATR) and FT-Raman spectroscopy between leukoplakia, oral cancer and normal tissues. Human tissue contains many compounds with known absorption spectra in the range of Near Infrared (NIR) spectroscopy. These compounds have a fingerprint region, which permits their characterization. FTIR spectroscopy is a promising diagnostic tool. There is ability to detect skin, cervix, prostate, breast, esophagus, stomach, bladder and oral cancers [1]. Imaging using FTIR microscope allows analysis of biochemical compounds in microregions of biological materials. FTIR microspectroscopy is the perfect technique for tissues and individual cells analysis [1]. It delivers information about biochemistry of cell or tissue samples and has been applied in many areas of medical research [2]. IR absorption spectra of abnormal tissues and normal tissues are compared by lipid (2800 - 3000 cm–1), protein (1500 - 1700 cm–1), and nucleic acids (1000 - 1250 cm–1) regions [2]. One of the mucous membrane lesions of the mouth is leukoplakia. This change has a “fingerprint region” in the range of 900 - 1800 cm–1 [3]. Raman spectroscopy has high potential of medical diagnosis. This method is a molecular specific technique that can be used to develop a fundamental biochemical understanding of tissue physiology and pathology. Both methods are dedicated to screening of preneoplastic and neoplastic tissues and have a potential to reduce morbidity of leucoplakia and oral cancers. Obtained data suggested that these infrared techniques are applicable to biomedical and clinical diagnostics.

Isolation and Characterization of Photodegradation Impurity in Budesonide Drug Product Using LC-MS and NMR Spectroscopy

Abstract: Budesonide is a corticosteroid used for the treatment of asthma via various matrices and inhalation mechanisms. An unknown peak of Budesonide aqueous formulation has been investigated during stability study wherein the impurity level observed around 0.1% well below the threshold 0.5%. The approach to identify anonymous species was adopted as first to generate the impurity in sample, isolate, enrich and was subjected to LC-MS/MS and NMR for spectral studies. Based on the spectral data the anonymous species were identified as a “Lumibudesonide’’ ((5aR,5bS,5cS,6S,7aS,7bS,10aR,11aS,11bS)-6-hydroxy-7b-(2-hydroxyacetyl)-5b,7a-dimethyl-9-propyl 1,5a,5b,5c,6,7,7a,7b,10a,11,11a,11b dodecahydrocyclopenta[2'',3'']cyclopropa [1'',2'':3', 4']benzo [1',2':4,5]indeno [1,2-d][1,3]dioxol-5(2H)-one), which is observed in photolysis of Budesonide.

Development and Validation of Stability Indicating Rapid RP-LC Method for Determination of Process and Degradation Related Impurities of Apremilast, an Anti-Inflammatory Drug

Abstract: A new, specific, rapid and stability indicating reversed phase liquid chro-matographic (RP-LC) method for the determination of process related and degradation related impurities of Apremilast has been developed and validated. The degradation study performed in acid, base, oxidative, photolytic, and thermal stressed conditions. Eight process related impurities (Imp-1 to Imp-8) in test sample of Apremilast have been detected by developed RP-LC method. The good chromatographic resolution between the peaks of process related impurities, degradation impurities and Apremilast has been achieved on a Synergi Max-RP 80 A (150 × 4.6 mm ID), 4 μ column. The process and degradation related impurities were characterized by mass spectrometry, 1H NMR and FT-IR spectral data. The method was validated as per ICH guideline and found to be specific, rapid, and stability indicating. The proposed RP-PLC method was successfully applied to the analysis of drug substance samples of Apremilast.

Analysis of Various Quality Attributes of Sunflower and Soybean Plants by Near Infrared Reflectance Spectroscopy: Development and Validation Calibration Models

Abstract: Soybean and sunflower are summer annuals that can be grown as an alternative to corn and may be particularly useful in organic production systems for forage in addition to their traditional use as protein and/or oil yielding crops. Rapid and low cost methods of analyzing plant forage quality would be helpful for nutrition management of livestock. We developed and validated calibration models using Near-infrared Reflectance Spectroscopic (NIRS) analysis for 27 different forage quality parameters of organically grown sunflower and soybean leaves or reproductive parts. Crops were managed under conventional tillage or no-till with a cover crop of wheat before soybean and rye-crimson clover before sunflower. From a population of 120 samples from both crops, covering multiple sampling dates within the treatments, calibration models were developed utilizing spectral information covering both visible and NIR region of 61 - 85 randomly chosen samples using modified partial least-squares (MPLS) regression with internal cross validation. Within MPLS protocol, we compared nine different math treatments on the quality of the calibration models. The math treatment “2,4,4,1” yielded the best quality models for all but starch and simple sugars (r2 = 0.699 - 0.999; where the 1st digit is the number of the derivative with 0 for raw spectra, 1 for first derivative, and 2 for second derivative, the 2nd digit is the gap over which the derivative is calculated, the 3rd digit is the number of data points in a running average or smoothing, and the 4th digit is the second smoothing). Prediction of an independent validation set of 28-35 samples with these models yielded excellent agreement between the NIRS predicted values and the reference values except for starch (r2 = 0.8260 - 0.9990). The results showed that the same model was able to adequately quantify a particular forage quality of both crops managed under different tillage treatments and at different stages of growth. Thus, these models can be reliably applied in the routine analysis of soybean and sunflower forage quality for the purposes of livestock nutrient management decisions.

Study on the Difference between Volatile Constituents of the Different Parts from Elsholtzia ciliata by SHS-GC-MS

Abstract: In this study, the comparison of Elsholtzia ciliata volatile compounds from the stem (with leaf) and flower was acquired. The volatile compounds of these two parts from Elsholtzia ciliata aerial parts were respectively analyzed by a rapid and convenient static headspace injection technique coupled with gas chromatography-mass spectrometry and the relative contents of each constituent between the two different parts were determined by peak area normalization. 61 compounds were identified in the stem (with leaf) and flower, among which 39 components simultaneously exist. 47 and 53 compounds were separated and identified in the volatile compounds from the different parts of Elsholtzia ciliata, respectively. There were differences among some volatile constituents of the two parts, but the main constituents were all Elsholtzia ketone, caryophyllene, 3-octanol and Dehydroelsholtzia ketone. The most abundant components in the stem (with leaf) included Elsholtzia ketone (84.20%), caryophyllene (4.3%) and 3-octanol (3.11%), while Elsholtzia ketone (88.03%), caryophyllene (3.33%) and 3-octanol (1.53%) were the main components in the flower. 8 single constituents were identified in the stem (with leaf) volatiles including 3-heptanone and linalool, while 14 constituents only including 2-methylbutanoic acid and Perillene have been found in the flower volatiles. Elsholtzia ketone was the main compound, and its concentration was significantly higher than other substances (>80% of the total oils in Elsholtzia ciliata). The study provided an important scientific base for the further utilization of Elsholtzia ciliata resources and may be helpful for systematically understanding the constituents of volatile compounds of Elsholtzia ciliata.

Potentiometric Study of Dissociation Constants of Dihydroxybenzoic Acids at Reduced Ionic Strengths and Temperatures

Abstract: The dissociation behavior of two dihydroxybenzoic acid isomers, 2,3-DHBA and 3,4-DHBA, at 281 K and 293 K was determined by potentiometric titrations in 0.01 M NaCl and 0.03 M NaCl. Results showed that the dissociation enthalpy for the carboxylic group in DHBA is close to zero, resulting in dissociation constants that do not vary appreciably with temperature, whereas the dissociation constants for the first hydroxyl group vary significantly with temperature. Increasing ionic strength was found to result in increased values for the second dissociation constant, whereas the effect on the first dissociation constant was less clear.

Investigation of the Low Molecular Weight Thiol Composition in a Metastatic Prostate Cancer Cell Line (LNCaP) by LC-UV-MS and NMR after Labelling with the Ellman Reagent

Abstract: The low molecular weight thiols present in the deproteinized extract of a prostate cancer cell line (LNCaP-FGC) were analysed after derivatization with the Ellman reagent (ESSE). The mixed disulphides formed (RSSE) were fractionated, characterized and quantified by liquid chromatography on a C-18 column using UV detection. This revealed the presence, in femtomoles per cell, of glutathione (8.30 ± 0.73), cysteine (2.71 ± 0.04) and cysteinylglycine (0.83 ± 0.10), accounting for the bulk of the thiol present. Further analysis of the cell extracts using a novel and sensitive mass spectrometry technique allowed the detection of low level of an additional derivative which was identified as cysteinylglycerate using NMRspectroscopy.

Rheological Properties of Six Plant-Based Seed Gums

Abstract: The rheological properties of six mucilage solutions (Guar Gum, Locust Bean Gum, Tamarind Gum, Flaxseed Gum, Artemisia Sphaerocephala Krasch Gum and Cassia Gum) have been examined. It was found that all six gums could be classified into three different types according to the changes of viscosity with increasing shear rate. Steady shear viscous properties in a range of shear rate from 0.1 to 100 s-1 were investigated in the provision of mucilage concentration, pH, temperature and salts. A non-Newtonian shear-thinning behavior was observed. The data of viscosity-shear successfully correlated Power law model. Apparent viscosity was apparently dependent on mucilage concentration increasing significantly as mass fraction went up. A marked dependence of viscosity on temperature was also observed; as temperature increased, the viscosity decreased sharply. The value n of flaxseed gum is minimum, which means it behaves the greatest shear-thinning properties. Both Guar gum and Tamarind gum possessed better acid-proof and alkali-proof advantages. The flow activation energy of ASKG is 4.3 kcal which is higher than other gums so that the influence of temperature on characteristics of viscosity is stronger. The mechanical spectra in the linear viscoelasticity region were studied in the temperature range from 20°C to 90°C, at a frequency range from 0.1 to 10 Hz. It was observed that Both elastic modulus G' and viscous modulus G" behaviors were found to be dependent on temperature and frequency. What have been investigated in this work could provide guidance for practical application in the field of food industry.

Detection and Separation of Inorganic Cations in Natural, Potable, and Wastewater Samples Using Capillary Zone Electrophoresis with Indirect UV Detection.

Abstract: Capillary zone electrophoresis (CZE) is a sensitive and rapid technique for determining traces of inorganic cations in water samples. CZE with indirect UV-diode array detection (CZE-DAD) was utilized to identify several inorganic cations in natural, potable, and wastewater samples. A pH 4.35 background electrolyte system was employed and consisted of 15 mM imidazole, 8 mM malonic acid, 2 mM 18-crown-6 ether as complexing agents, 10% v/v methanol as an organic modifier with indirect absorbance reference at 214 nm. The CZE method involved electromigration injection at 5 kV for 5 s, a separation voltage of 20 kV at 25℃, and a detection wavelength of 280 nm. Six main cations (ammonium , potassium K+, calcium Ca2+, sodium Na+, magnesium Mg2+, and lead Pb2+) were tested, and all but lead, were detected in the water samples at concentrations between 0.03 and 755 ppm with a detection limit ranging between 0.023 and 0.084 ppm. The successful evaluation of the proposed methodology allowed us to reliably detect and separate six metal ions in different water samples without any pretreatment. All water samples were collected from Northern New York towns and the Raquette River water system, the third longest river in New York State and the largest watershed of the central and western Adirondacks.

Influence of Nitro Group Substitutes to the Stability and Energetic Properties of N-(2,4,6-trinitrophenyl)-1 H - 1,2,4-triazol-3-amine

Abstract: In the paper, we aim to show N-(2,4,6-trinitrophenyl)-1H-1,2,4-triazol-3-amine (HM-I) as explosive material that satisfies requirements of sensitivity and hydrolytically stability. The influence of nitro group substitutions on the thermal and chemical stability as well as the explosive performance of HM-I is also investigated. We found that nitro group substitution to the triazole ring of HM-I can significantly improve the properties of this new material. Only -NH2 substitution position (but not their number) in the core molecule is appropriate to increase the stability and improve explosive performances of HM-I.

Trace Determination of Duloxetine HCl in Formulation and Spiked Human Serum at a Carbon Paste Electrode

Abstract: The electrochemical behavior of duloxetine HCl (DXT.HCl) at a carbon paste electrode (CPE) was achieved by cyclic voltammetry and a mechanism of its oxidation was reported and illustrated. A sensitive linear sweep and square-wave adsorptive anodic stripping voltammetry methods were described for trace determination of DXT.HCl. Introduction: DXT.HCl, N-methyl-3-(nap-thalen-1- yloxy)-3-(thiophene-2-yl) propan-1-amine hydrochloride is a selective serotonin-norepinephrine reuptake inhibitor (SNRI) originally developed as an antidepressant and is currently recommended for maintenance treatment of major depressive disorder. Methods: Electrochemical behavior was studied using cyclic voltammetric method, and the analytical application was studied using linear sweep and square wave voltammetric methods. Solution pH has been measured by pH meter. Results: The process on the surface of carbon paste electrode was found to be irreversible and diffusion-controlled. The number of proton and electron transferred were calculated. Possible reaction mechanism taking place on the surface of electrode was proposed. Calibration plot constructed using square wave voltammetric technique was used for quantitative analysis in pharmaceutical and human serum samples. Limit of detection (LOD) and limit of quantification (LOQ) were calculated. Conclusions: In the present work, we described the electrochemical behavior of DXT.HCl drug. Two precise linear sweep and square wave adsorptive anodic stripping voltammetry methods have been described for its trace quantitation in pharmaceutical formulation and human serum. The method shows the development of a sensor for selective and sensitive determination of DXT.HCl.

Validation and Comparison of Two Calibration Methods for the Measurement of Stable Iodine in the Urinary Matrix by ICP-MS: Standard Addition vs. External Calibration

Abstract: Background: In the context of a nuclear reactor accident, thyroid is the main target organ of radioactive iodines. To avoid as much as possible thyroid disorders or even cancer development, it is recommended to administer a single dose of potassium iodide to people at risk of exposure. Nevertheless, the Fukushima Dai-ichi disaster has pointed out many questions about the conditions of stable iodine prophylaxis implementation highlighting the need for reflection further revision of the actual “iodine doctrine”. Therefore, providing useful data is required notably through the implementation of animal experiments to strengthen current knowledge and to edit new recommendations. Methods: Urinary iodine constitutes a very good indicator to investigate the function of thyroid, its interpretation demands reliable analyses. Prior to perform animal experiments, two calibration methods were designed by our lab and compared together (standard addition and external calibration) to assess the urinary concentration of stable iodine in urine by ICP-MS. They were validated based on several key parameters especially linearity, accuracy and limits of detection (LOD) and quantification (LOQ). Results: The results were nicely satisfying. Indeed, both calibration methods have indicated very good coefficients of correlations, accuracies with low expanded relative uncertainties were obtained. The estimated LOD in the sample for standard addition method and external calibration were fully acceptable, 0.39 μg·L-1 and 0.35 μg·L-1, respectively. All performance criteria have been thus fulfilled successfully. The established methods were proven to be accurate, robust and sensitive. Once validated, both calibration methods were applied to rat urine samples and the results of z-score and Wilcoxon W test concluded that there were no statistically significant differences between both methods.

Assessment of Phytochemicals, Proximate and Elemental Composition of Pterocarpus soyauxii (Oha) Leaves

Abstract: The proximate, elemental and phytochemical compositions of the leaves of Pterocarpus soyauxii (Oha) were studied. The results obtained for the proximate composition showed the following: moisture content (17.2%), ash content (5.7%), crude fibre (17.2%), crude protein (29.5%), crude fat (4.15%) and carbohydrates (25.95%). The results of the mineral (elemental) analysis in mg/L showed the following to be present in the leaves: Ca (4.04), Cu (0.20), Zn (1.39), Mg (41.0), K (0.31), Mn (0.17), Na (32.0) and Fe (0.60) with Pb and Cr absent. The leaves also contained vitamin A (0.2044 mg/g) and vitamin C (0.4470 mg/g). The phytochemical analysis of different solvent extracts showed the presence of alkaloids, saponins, glycosides and tannins. Flavonoids, phenols and steroids were absent. These findings showed that the leaves of Pterocarpus soyauxii are good sources of beneficial micronutrients, mineral elements and secondary metabolites which are required for healthy growth, justifying the use of the leaves for the popular “Oha” soup of the Igbos of South East Nigeria.

GC/FT-IR Analysis of Novel 4,6,9-Triene and 2,4,6,9-Tetraene Occurring in a Female Pheromone Gland of Arctia plantaginis (Erebidae: Arctiinae)

Abstract: Fifteen subspecies of the wood tiger moth, Arctia plantaginis (Lepidoptera: Erebidae: Arctiinae), have been recorded in the Northern Hemisphere. An analysis of crude pheromone extracts by GC equipped with an electroantennographic (EAG) detector showed four EAG-active components (Comps. I–IV) that were commonly involved in the pheromone glands of two subspecies inhabiting Japan and Finland. Comp. I is a major component (>75%) and the others are minor components (3% - 15%). Their mass spectra, measured by GC/MS, revealed the chemical structures of C21 unsaturated hydrocarbons as follows: 3,6,9-triene for Comp. I, 4,6,9-triene for Comp. II, 1,3,6,9-tetraene for Comp. III, and 2,4,6,9-tetraene for Comp. IV. Comps. I and III are known Type II pheromone compounds, and their retention times coincide with those of the authentic standards with all Z configurations. As a next step, the extract was analyzed by GC/FT-IR to determine the configuration of Comps. II and IV. Their IR spectra showed two characteristic C-H bending absorptions around 990 and 945 cm-1 due to the conjugated dienyl moieties; thus, Z and E configurations were assigned to the double bonds at the 2- and 4-positions, respectively. Their Z double bonds at the 6- and 9-positions are indicated by no absorptions around 970 cm-1, due to the isolated double bonds with E configurations. Finally, the structures of Comps. II and IV were confirmed by synthesis using a double Wittig reaction. The synthetic (4E,6Z,9Z)-4,6,9-triene and (2Z,4E,6Z,9Z)-2,4,6,9-tetraene showed strong EAG activity, and their chemical data coincided well with those of the natural Comps. II and IV, indicating the correctness of the structure determination by GC/FT-IR analysis and its usefulness for Type II pheromone compounds.

The Thermal Decomposition of Ammonium Meta-Vanadate under Restricted Flow Conditions

Abstract: The products obtained during the thermal decomposition of ammonium meta-vanadate depend on the configuration of the container, the mass of the sample, the heating rate and the composition of the carrier gas. The decomposition in an uncapped container produced (NH4)2V4O11, NH4V3O8, and V2O5 as the apparent stable products while the products in a capped container were NH4V3O8, and V2Ox where x was between 4 and 5. These differences are attributed to the different amounts of the evolved gases in the cell. EGA-FTIR clearly established that the reduced final product in the capped cell resulted from a reaction between NH3 and the V2O5 formed during the decomposition. A pre-equilibrium kinetics model where the rate of the reverse reaction depends on the partial pressure of the gaseous products in the cell could explain the different reaction intermediates. This model provides a possible explanation for the different apparent activation energies that have been reported for the thermal decomposition of other compounds where a reversible step could occur in the decomposition mechanism.

Preliminary Phytochemical Content and Antidiabetic Potential Investigations of Panda oleosa (Pierre) Used in Kisangani Areas

Abstract: Panda oleosa Pierre (POP), a tropical plant tree, has been used in traditional medicine in Kisangani city and around to treat various diseases including diabetes and HIV/AIDs. This study aims to evaluate the chemical composition of POP extracts while setting up chromatographic fingerprints for their quality control, and the anti-hyperglycemic potential of trunk bark aqueous extracts of POP. Common chemical reactions were used for identification of main secondary metabolic groups. Thin layer chromatography was used to set up several chromatographic fingerprints of water and alcoholic extracts while evaluating chemical composition. Oral glucose tolerance test served to induce hyperglycemia in a rabbit model. The extracts were given as 25 mg/kg, 50 mg/kg, and 100 mg/kg body weight, 30 minutes before loading animals with glucose 4 g/kg. Blood samples were collected at various times: just before extracts (T-30), before (T0) and after glucose load (T30, T60, T120, and T180). Blood glucose levels were measured with One Touch Glucometer. The identification tests revealed the presence of saponins (3.58%), tannins (5%); alkaloids, quinones, flavonoids, and terpenes sterols could not be formerly detected by the reagents used. Interesting chromatographic spots were observed whose behaviors are of catechic tannin proanthocyanes. The extract significantly reduced glucose levels in dose dependent manner as compared to control and glibenclamide reference groups. The average of mean percentage of reduction in glucose level at T120 with the extract 100 mg/kg was close to that of glibenclamide 0.25 mg/kg (49% and 40.2%). These findings back the traditional use of the plant to treat diabetic patients and constitute a foundation for an extensive study to find a new antidiabetic phythomedicine.

Purification of Nanoparticles by Liquid Chromatography for Biomedical and Engineering Applications

Abstract: Nanoparticles are extensively used for various applications in science, engineering and medicine. Synthesis of nanoparticles with high purity is essential to utilize the same in different fields of science and technology. In the present study, liquid chromatography is utilized to purify the nanoparticles. Predominantly, gold nanoparticles were synthesized from gold auric cholide and preserved in phosphate or citrate buffer. A method to purify gold nanoparticles is essential because of the possible interference from gold auric chloride and other impurities in buffer. Herein, a method has been developed using high performance liquid chromatography to purify gold nanoparticles with 100 nm in size from gold auric chloride and residues. UV-Vis spectroscopy was also done to ascertain the purity of the nanoparticles.

Assessment of Minor and Trace Elements in Aquatic Macrophytes, Soils and Bottom Sediments Collected along Different Water Objects in the Black Sea Coastal Zone by Using Neutron Activation Analysis

Abstract: The levels and compartmentalization of Na, Mg, Al, Cl, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, As, Se, Br, Rb, Sr, Mo, Sb, I, Cs, Ba, La, Ce, Sm, Eu, Tb, Hf, Ta, Au, Th, and U in Phragmites australis (Cav.) Trin. ex Steud., Carex conescens L. and Cladophora sericea (Hudson) Kutzing from the Caucasian coast of the Black Sea-Anapa recreational region was investigated by Neutron Activation Analysis. The study touches upon subject of the sediment-to-plant and root-to-leaf elemental transfer as well as of the influence of anthropogenic pollution on wetland ecosystems in zone of resort. The content of the majority of considered elements was found higher in the belowground organs of P. australis than in the aboveground tissues while a reverse regularity was evidenced for C. conescens. The levels of elements decrease from bottom sediments to aquatic plants with the notable exception of the halogens Cl, Br and I that presented 5 to 100 fold higher content in plants than in sediments. The increased levels of As, Mo, and Sb in some soil and sediment samples most probably indicate the anthropogenic pollution. It recommends them for a continuous monitoring of the same area.

An Energy Analysis on Gasification of Sewage Sludge by a Direct Injection in Supercritical Water

Abstract: Supercritical Water Gasification is an efficient technology in converting wet biomass into H2 and CH4 in comparison to other conventional thermochemical processes. Coke deposition, however, remains as a major challenge in this technology. Coke formation is the result of polymerization reactions that take place at sub-critical conditions. Directly injecting the relatively unheated wet biomass feed into supercritical water increases the heating rate and reduces the residence time of the feed in the sub-critical condition. This leads to a minimized coke formation in the process. However, a non-isothermal mixing takes place during this direct injection that is less energy-efficient. In addition, the biomass feedstream experiences less pre-heating that means less heat recovery from the product gas. These two aspects might reduce the overall process performance. Parametric studies of key operating parameters, such as operating temperature, dry matter content, bypass water ratio and heat exchanger effectiveness, are carried out to investigate the influence of direct injection to the thermal efficiency of the system. Subsequently, optimization using pinch analysis is conducted to the system with direct injection. Finally, an operating window for optimum performance of the optimized direct injection gasification system is proposed.

A New Insight in the Physical and Photoelectrochemical Properties of Molybdenum Disulfide Alpha-Hematite Nanocomposite Films

Abstract: The alpha (α)-hematite (Fe2O3) as photoanode has been used for photoelectrochemical applications due to low bandgap, low cost, high chemical stability, nontoxicity, and abundance in nature. The doping with various transition metals, formation of nanostructured and nanocomposite of α-Fe2O3 have been attempted to enrich the carrier mobility, surface kinetics and carrier diffusion properties. The manuscript is an attempt to improve the photoelectrochemical properties of α-Fe2O3 by formation of nanocomposite with dichalcogenide (molybdenum disulfide (MoS2) nanomaterials. The nanocomposite of MoS2-α-Fe2O3 have been synthesized by varying the amount of MoS2 in sol-gel synthesis process. The nanocomposite MoS2-α-Fe2O3 materials were characterized using UV-visible, FTIR, SEM, X-ray diffraction, Raman and particle analyzer. The photoelectrochemical properties were investigated using cyclic voltammetry and chronoamperometry studies. The optical and structural properties of MoS2-α-Fe2O3 nanocomposite have been found to be dependent on MoS2 doping. The band gap has shifted whereas; the structure is more prominent as flower-like morphology, which is a result of doping of MoS2. The photocurrent is more pronounced with and without light exposition to MoS2-α-Fe2O3 based electrode in photoelectrochemical cell. We have understood the photoelectrochemical water splitting using nanocomposite α-Fe2O3-MoS2 through schematic representation based on experimental results. The enhanced photoelectrochemical properties of nanocomposite α-Fe2O3-MoS2 films have been observed as compared to pristine α-Fe2O3 and transition metal doped α-Fe2O3 nanostructured films.

The Use of Eucalyptus Activated Biocarbon for Water Treatment-Adsorption Processes

Abstract: A biocarbon after activation process showed the removal percentage of 92% of methylene blue in solution, the equilibrium parameter—RL value was in the interval from 0 to 1, with 46% of surface coverage degree. The Freundlich constant (n) was higher than 1 as an indication of the physical adsorption process. The Radlich-Peterson calculations obtained the higher R2 value which g constant near 1, a high similarity with Langmuir model. Temkin constant B1 was a positive indication of endothermic process. All calculations provided favorable results for the use of activated biocarbon for dye removing and possible for other organic substances.

Co-Combustion Characteristics and Kinetics of Cotton Stalk and Polypropylene Blends

Abstract: The combustion kinetics of biomass-cotton stalk (CS), polymer-polypro-pylene (PP) and blend of polymer/biomass-polypropylene/cotton stalk blends were examined through thermo gravimetric analysis in this study. The experiments were performed under non-isothermal conditions in the 298 - 873 K temperature interval. The heating rate of this research realized under the air atmosphere was designated as 5 K·min-1. The particle size effect on the combustion behavior of cotton stalk was also studied. A decrease in the maximum rate of decomposition and an increase in the temperature of maximum decomposition with increasing particle size were obtained. Three different models based on the Arrhenius method were used to analyze differential thermo gravimetric data. Blending ratio effects of biomass-cotton stalk and polymer-polypropylene on the combustion kinetics were further explored. Additionally, factors and kinetic parameters were also discussed. Activation energies obtained through the Arrhenius method (n = 1) were much lower than that of polypropylene for all blends. As a result of the research, as the weight percentage of polypropylene in the mixture rises, an increase in activation energy values was observed. The minimum value of the activation energy was calculated with PP/CS with 2/3 blending ratio as 35.8 kJ·mol-1.

Treatment of the High Concentration Nonylphenol Ethoxylates (NPEOs) Wastewater by Fenton Oxidation Process

Abstract: The Fenton oxidation process was applied in the treatment of an actual high concentration nonylphenol Ethoxylates (NPEOs) wastewater. The effects of H2O2 dosage, molar ratio of H2O2/Fe2+ (Fe2+ dosage), pH value and reaction time on the degradation of NPEOs were investigated. The orthogonal experiment indicated that the order of degree of influence on the COD removal was molar ratio of H2O2/Fe2+, reaction time, dosage of H2O2, and initial pH. The single-factor tests were carried out to determine the optimal conditions, and the results were H2O2 dosage of 76.32 mmol/L, molar ratio of H2O2/Fe2+ of 3, pH value of 5 and reaction time of 2 h. Under the optimum operation conditions, the COD removal efficiency was 85.6% and the effluent could be mixed with other wastewater into the large-scale biological treatment system.

Derivative Spectrophotometric and Isocratic High Performance Liquid Chromatographic Methods for Simultaneous Determination of Repaglinide and Metformin Hydrochloride in Pharmaceutical Preparations

Abstract: In this study, a derivative spectrophotometric method and one HPLC method were developed and validated for analysis of anti-diabetic drugs, repaglinide (RPG) and metformine hydrochloride (MTF) in tablets. The spectrophotometric methods were based on zero-crossing first-derivative and fourth-derivative spectrophotometric method for simultaneous analysis of RPG (308 nm) and MTF (267 nm), respectively. Linear relationship between the absorbance at λmax and the drug concentration was found to be in the ranges of 5.0 - 50.0 μg·mL-1 for both RPG and MTF. The quantification limits for RPG and MTF were found to be 0.568 and 1.156 μg·mL-1, respectively. The detection limits were 0.170 and 0.347 μg·mL-1 for RPG and MTF, respectively. The second method is a rapid stability-indicating isocratic HPLC method developed for the determination of RPG and MTF. A linear response was observed within the concentration range of 5.0 - 50.0 μg·mL-1 for both RPG and MTF. The quantification limits for RPG and MTF were found to be 1.821 and 1.653 μg·mL-1, respectively. The detection limits were 0.601 and 0.545 μg·mL-1 for RPG and MTF, respectively. The proposed methods were successfully applied to the tablet analysis with good accuracy and precision.

Comparison between Glass and Stainless-Steel Vessels in Differential Scanning Calorimetry Estimation

Abstract: Differential scanning calorimetry (DSC) provides easy screening for thermal hazard evaluation. Here, we investigate the difference between using glass and stainless-steel vessels on the DSC measurement of exothermic decomposition energy (QDSC) for 41 chemical substances (containing nitro, halogen, peroxide, and sulfur groups, and hydrazine bonds). Two borosilicate glass vessels (capillary and ampule) and one stainless-steel vessel were used. All QDSC values obtained were investigated with reference to the permissible fluctuation range specified by the ASTM (American Society for Testing and Materials) international Both glass vessels produced very similar QDSC values, despite different sample scales. The QDSC values obtained with the glass vessels were generally roughly within the variation tolerance range of the stainless-steel vessel. Notable exceptions were halogen- or sulfur-containing compounds; these exhibited smaller QDSC values with glass vessels in almost all cases. We will investigate whether certain structures in compounds react with stainless steel. The vessel material choice is crucial in evaluating the true reactivity of a substance.