Factorial Design Optimization of Solid-Phase Microextraction for High-Performance Liquid Chromatography−Ultraviolet Spectrometry Analysis of Polycyclic Aromatic Hydrocarbons in Cigarette Filter Tar

A simple and rapid procedure for the determination of polycyclic aromatic hydrocarbons (PAHs) in cigarette filter tar using solid-phase microextraction (SPME) was developed. The analysis was carried out using high-performance liquid chromatography equipped with an ultraviolet detector. The effects of the SPME experimental parameters on the extraction recovery were studied simultaneously using a central composite design (CCD) after a 2^6?2 fractional factorial experimental design. The SPME variables of interest were the extraction temperature, the extraction time, and the stirring speed, as well as the pH and the concentrations of NaCl (%, w/v) and acetonitrile (ACN). The optimal SPME conditions were as follows: an extraction temperature of 65°C, an extraction time of 50 min, a stirring speed of 800 rpm, 0% NaCl (w/v), 10% ACN in the sample, and a source pH of 8.0. The extraction calibration plots were linear over the range of 0.25?20 ng mL^?1 (r² > 0.9912) and the limits of detection (LODs) for the 6 PAHs studied were from 0.17–5.02 ng cigarette^?1. The relative standard deviation (RSD) ranged from 7.1–13.5% for intra-day variation and from 8.5–18.4% for inter-day variation. The performance of the proposed method was evaluated for extraction and determination PAHs in real samples (various brands of cigarettes). The total amounts of all of the studied PAHs found in the filter tar of the three brands of cigarettes were 320.2, 17.9, and 66.7 ng cigarette^?1, respectively.     

Effect of processing methods and starter culture (Staphylococcus xylosus and Pediococcus pentosaceus) on proteolytic changes in Turkish sausages (sucuk) during ripening and storage

Proteolytic changes in Turkish sausages (sucuk) produced by two methods (heat processing and traditional) were determined during processing and storage for 90 days. The sausages were produced with or without starter culture in both methods. A mixture of Staphylococcus xylosus and Pediococcus pentosaceus was used as starter culture for their acidic and proteolytic characteristics.The major changes in proteolytic characteristics of sucuk took place during the fermentation stage, with an increase in non-protein nitrogen (NPN) and a decrease in protein solubility. Proteolytic activity was observed in both starter-inoculated and non-inoculated (control) sausages during processing. Moreover, a slight increase in proteolytic activity was detected during storage in both starter-inoculated and control traditional sausages, and also in heat-processed sausages due to some heat-resistant proteolytic enzymes. Protein solubility was significantly affected by processing time and heat treatment. Sarcoplasmic and myofibrillar proteins were also affected by starter addition, fermentation, drying and heat processing. During fermentation, starter-inoculated and control sausages showed intense proteolysis in both the traditional and heat processing methods. After heating, intensive degradation of both sarcoplasmic and myofibrillar proteins due to denaturation was observed in heat-processed samples.     

Testing of drug release from bioadhesive vaginal tablets

To establish an in vitro test method that can predict the drug release and dissolution behaviour of vaginal bioadhesive controlled release tablets, a system was developed and its appropriateness to the in situ conditions was examined. For this purpose, the dissolution rates of vaginal bioadhesive tablets were measured by three different methods. These were, USF dissolution tester apparatus two and a new vaginal dissolution tester (NVDT) which was developed by us with some modification of the vaginal tablet desentegration apparatus of BP 1988 and, testing in cow vaginas in situ. Four different bioadhesive tablet formulations were used being composed of the drug and the anionic polymer, polyacrylic acid (PAA) and the nonionic polymers, hydroxypropylmethyl cellulose (HPMC) and ethycellulose (EC). The release profiles of the in vitro and in situ methods were ivestigated and evaluated kinetically     

Biosorption of Acid Red 274 (AR 274) on Enteromorpha prolifera in a batch system

The biosorption of Acid Red 274 (AR 274) dye on Enteromorpha prolifera, a green algae grown on Mersin costs of the Mediterranean, Turkey, was studied as a function of initial pH, temperature, initial dye and biosorbent concentration. The experiments were conducted in a batch manner. The Langmuir and Freundlich isotherms were used for modelling the biosorption equilibrium. At optimum temperature 30 degrees C and initial pH 2.0-3.0, the Langmuir isotherm fits best to the experimental equilibrium data with a maximum monolayer coverage of 244 mg/g. The equilibrium AR 274 concentration of the exit stream of a single batch was also obtained by using the experimental equilibrium curve and operating line graphically. The pseudosecond-order kinetic model and Weber-Morris model were applied to the experimental data and it was found that both the surface adsorption as well as intraparticle diffusion contribute to the actual adsorption process. The biosorption process follows a pseudosecond-order kinetics and activation energy was determined as -4.85 kJ/mol. Thermodynamic studies showed that the biosorption of AR 274 on E. prolifera is exothermic and spontaneous in nature.     

Adsorption of o-, m- and p-nitrophenols onto organically modified bentonites

Experiments were conducted on the adsorption characteristics of o-, m- and p-nitrophenols by organically modified bentonites at different temperatures. Two organobentonites (HDTMA-B and PEG-B) were synthesized using hexadecyltrimethylammonium bromide (HDTMABr) and poly(ethylene glycol) butyl ether (PEG). Synthesized HDTMA-B and PEG-B were characterized by XRD, FTIR and DTA-TG analyses and their specific surface area, particle size and pore size distributions were determined. BET surface areas and basal spacings (d(001)) of the HDTMA-B and PEG-B were found to be 38.71 m(2)g(-1), 69.04 m(2)g(-1) and 21.96 ?, 15.17 ?, respectively. Increased adsorption with temperature indicates that the process is endothermic for o-nitrophenol. On the other hand m- and p-nitrophenols exhibited lower rates of adsorption at higher temperatures suggesting a regular exothermic process taking place. Results were analyzed according to the Langmuir, Freundlich and Dubinin-Redushkevich (D-R) isotherm equations using linearized correlation coefficient at different temperatures. R(L) separation factors for Langmuir and the n values for Freundlich isotherms showed that m- and p-nitrophenols are favorably adsorbed by HDTMA-B and, p-nitrophenol is favored by PEG-B. Adsorption of o-, m- and p-nitrophenols as single components or from their binary mixtures on HDTMA-B and, p-nitrophenol on PEG-B are all defined to be physical in nature.     

Effect of plant extracts on lipid oxidation during frozen storage of minced fish muscle

The aim of the study is to determine the effect of pomegranate seed extract (PSE) and grape seed extract (GSE) addition to chub mackerel minced muscle on lipid oxidation during frozen storage. Each extract was added to minced fish muscle at 2% concentration and then stored at ?18 °C for 3 months. The effect of plant dietary fibres to control lipid oxidation was compared with untreated samples (control). Formation of lipid hydroperoxides and thiobarbituric acid‐reactive substances (TBARS) was significantly inhibited by PSE and GSE addition when compared with control. Both extracts significantly retarded lipid oxidation according to the results of TBARS. A significant reduction of L* (lightness), a* (redness) and b* (yellowness) values was detected during frozen storage. GSE added samples had the highest redness and the lowest lightness and yellowness. However, samples with PSE showed the lowest redness and highest yellowness and h° (hue angle) values. The results from this study suggest GSE is a very effective inhibitor of primary and secondary oxidation products in minced fish muscle and have a potential as a natural antioxidant to control lipid oxidation during frozen storage of fatty fish.     

Application of Fuzzy Control in a Wireless Liquid Level Simulator

Wireless Personal Communications - Liquid level control has great proposition in terms of chemical processes. It is important to make the level measurement in the tanks filled with industrial...     

Application of O3/UV/H2O2 oxidation and process optimization for treatment of potato chips manufacturing wastewater

Effluents coming from potato chips manufacturing have high organic loads and require adequate treatment before discharge to environment. In this study, O₃/UV/H₂O₂ advanced oxidation process was applied to treat these wastewaters. With this aim, batch experiments were conducted in a reaction tank equipped with ozone injection and UV irradiation. Process variables were determined to be pH, ozone concentration, reaction time, H₂O₂ dosage and efficiency of the system was evaluated considering total organic carbon (TOC) removal. Central composite design technique was applied to examine the individual and synergetic effects of the experimental factors. A quadratic model was developed to maximize the TOC removal. Furthermore, operation costs were calculated for different experimental conditions and interactions between process variables and costs were analysed.     

Comparison of chitosan apatite composites synthesized by different methods

This article presents some results concerning chitosan apatite composites obtained by two different methods. First method is based on phosphorylation, calcification and soaking in different calcium phosphate growth media (1.5 × SBF (simulated body fluid), Ca‐PTris (calcium phosphorous tris) and the second method is based on mixing of calcium deficient apatite powder with a chitosan solution. This research is focused on studying and understanding the effect of using different methods on Ca:P ratio of composites. The Ca:P ratio of composites formed in 1.5 × SBF are closer to that of bone when compared with the Ca:P ratio of composites formed in Ca‐PTris solution and Ca:P ratio of composites formed by mixing of calcium deficient apatite powder with a chitosan solution. The Ca:P ratio of the composite (1.75) immersed in 1.5 × SBF for 35 day is similar to the theoretical value of hydroxyapatite (1.67) and equal to the theoretical value of human bone (1.75). POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Die Verwendung von Ablaugenlignin bei der Herstellung von Holzwerkstoffen

Lignins occurring in the spent liquors of pulp mills constitute large potentials as raw materials for wood adhesives. As a polyphenol, lignin contains reactive sites for condensation with formaldehyde or intramolecular reactions leading to cross-linked, insoluble resins. However, condensation reactions of this type need high temperatures or mineral acids. Another procedure consists of radical cross-linking by oxidative coupling. Up to now these procedures have not found technical application, due to corrosion and other problems. In contrast, up to 25% of conventionally used phenolic resin adhesives can presently be substituted by technical spent sulfite liquor.