A sequential enzymatic microreactor system for ethanol detection of gasohol mixtures

A sequential enzymatic double microreactor system with dilution line was developed for quantifying ethanol from gasohol mixtures, using a colorimetric detection method, as a new proposal to the single micro reactor system used in previous work. Alcohol oxidase (AOD) and horseradish peroxidase (HRP) immobilized on glass beads, one in each microreactor, were used with phenol and 4-aminophenazone and the red-colored product was detected with a spectrophotometer at 555 nm. Good results were obtained with the immobilization technique used for both AOD and HRP enzymes, with best retention efficiencies of 95.3 ± 2.3% and 63.2 ± 7.0%, respectively. The two microreactors were used to analyze extracted ethanol from gasohol blends in the range 1–30 % v/v (10.0–238.9 g ethanol/L), with and without an on-line dilution sampling line. A calibration curve was obtained in the range 0.0034–0.087 g ethanol/L working with the on-line dilution integrated to the biosensor—FIA system proposed. The diluted sample concentrations were also determined by gas chromatography (GC) and high-pressure liquid chromatography (HPLC) methods and the results compared with the proposed sequential system measurements. The effect of the number of analysis performed with the same system was also investigated.     

Über Metallkomplexe heterocyclisch substituierter Formazane und Azomethine

Zusammenfassung Es wurden zwei neue Formazane, und zwar 1-Phenyl-5-(2-carboxyphenyl)-3-(3-methyl-2-chinoxalyl)-formazan und 1-Phenyl-5-(2-carboxyphenyl)-3-(3-methyl-2-chinolyl)-formazan synthetisiert. Diese Verbindungen bilden mit Uranyl-, Kobalt-und Nickelionen gut definierte Komplexe. Bei ihren Uran- und Kobaltkomplexen wurde ein Metall/Formazan-Verhältnis von 12, bei den Nickelkomplexen dagegen 11 festgestellt. Außerdem wurden Kobalt- und Nickelkomplexe des 3-Methylchinoxalin-2-aldehyd-o-hydroxy-anils mit einem Metall/Formazan-Verhältnis von 12 dargestellt.

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Metal complexes of heterocyclic substituted formazans and azomethines

Two new formazans, 1-phenyl-5-(2-carboxyphenyl)-3-(3-methyl-2-quinoxalyl)-formazan and 1-phenyl-5-(2-carboxyphenyl)-3-(3-methyl-2-quinolyl)-formazan have been synthesized. These compounds form well defined complexes with uranyl, cobalt and nickel ions. The ratio of metal/formazan in uranium and cobalt complexes is 12, in nickel complexes 11. Besides, cobalt and nickel complexes of 3-methyl-quinoxaline-aldehyde-o-hydroxy-anil were synthesized with a metal/azomethine ratio of 12.

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Teil der DissertationB. Ocakcioglu, Univ. Istanbul 1969.     

A quantum mechanical approach to electrochemical behavior of spirochromics

Fully optimized semiempirical quantum‐chemical calculations of photochromic spiropyrans are presented. The vertical ionization potentials are calculated and their variation with substitutions are correlated to experimental oxidation potentials. The effects of the substitutions are studied and the partial charges on indoline and pyran components generated by HOMO are found to be responsible for the variations. The deactivating groups on the indoline ring system and deactivating groups on the pyran system increase the ionization potential and, consecutively, the oxidation potential. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 75: 111–117, 1999     

Ring opening process of some spirochromenes by photoproduced HCl in poly(N-vinyl carbazole)

The coloration reaction of some spirochromenes (SP) has been investigated in the case of a free radical photosensitive system composed of a poly(N-vinylcarbazole) matrix (PVCz) in dichloromethane containing carbon tetrachloride as an activator at average ratios of 5:1:0.1 for PVCz, CCl₄ and SP, respectively. In this system, photoproduced HCl leads to the formation of the colored forms of SP. Acidification and irradiation of the variety of spirochromene solutions in the presence and absence of PVCz were also investigated and compared with the effect of photoproduced HCl on the reversibility of the ring opening process. The opened forms of the compounds were characterized by UV–visible spectra, pH and conductivity measurements. The effect of solvent and the substituent of SP were investigated. Decoloration reactions of the opened forms of SP at 50°C were followed using UV–visible spectroscopy, pH and conductivity measurements. © 1997 John Wiley & Sons, Ltd.     

Integrated Biosensor Systems for Ethanol Analysis

Different integrated systems with a bi-enzymatic biosensor, working with two different methods for ethanol detection—flow injection analysis (FIA) or sequential injection analysis (SIA)—were developed and applied for ethanol extracted from gasohol mixtures, as well as for samples of alcoholic beverages and fermentation medium. A detection range of 0.05–1.5 g ethanol/l, with a correlation coefficient of 0.9909, has been reached when using FIA system, working with only one microreactor packed with immobilized alcohol oxidase and injecting free horseradish peroxidase. When using both enzymes, immobilized separately in two microreactors, the detection ranges obtained varied from 0.001 to 0.066 g ethanol/l, without on-line dilution to 0.010–0.047 g ethanol/l when a 1:7,000 dilution ratio was employed, reaching correlation coefficients of 0.9897 and 0.9992, respectively. For the integrated biosensor SIA system with the stop–flow technique, the linear range was 0.005–0.04 g/l, with a correlation coefficient of 0.9922.     

Interaction of metal ions with polypyrrole on polyacrylic acid matrix

The oxidative matrix polymerization of pyrrole (Py) by Fe(III), Cu(II), Ni(II), Co(II), and Zn(II) in the presence of polyacrylic acid (PAA) was studied and water‐soluble products along with insoluble products were obtained. The metal (Me) content of the insoluble part was determined by using atomic absorption spectroscopy (AAS). The effects of the oxidation potential of Me ions and ligands on the aggregation of polypyrrole (PPy) on the matrix polymer were measured by ultraviolet (UV)‐visible spectra. These findings also were checked by cyclic voltammetry (CV) measurements on PAA–Cu and PAA–PPy–Cu interactions. The conductometric titration results of PAA–PPy–Me ternary solutions were explained in the light of the interaction of Me ions with Py to polymerize on the PAA matrix resulting in some free carboxyl groups with a possibility of having Me–polymer complexes and a ternary complex (PAA–Me–PPy). The insoluble products were characterized by Fourier transform infrared (FTIR), elemental analysis, scanning electron microscopy (SEM), and four point probe conductivity measurements. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1115–1123, 1999     

Oxidative polymerization of pyrrole in polymer matrix

The oxidative matrix polymerization of pyrrole (Py) by Ce(IV) in the presence of Polyacrylic acid (PAA) has been studied to obtain water-soluble and insoluble products. The role of the PAA, Pyrrole, and Ce(IV) concentration, order of component addition, the structure of polymer matrix (PAA, Hydroxy Ethyl Cellulose (HES), Poly-N-vinylpyrrolidone (PVP)], and model unit of PAA (propionic acid), on the polymerization system were investigated. Interaction of PAA with insoluble polypyrrole (PPy) and the interpolymer complex formation were investigated along with the aggregation of PPy onto the matrix polymer followed by spectral shifts. FTIR results of insoluble products obtained from the PAA–Py–Ce(IV) system and solubility of the system is explained in light of the mechanism of the polymerization of pyrrole on the polymer matrix. © 1995 John Wiley & Sons, Inc.     

Synthesis and Crystal Structure of Dimethyl-7-oxabicyclo[2.2.1]hept-5-ene exo,exo-2,3-dicarboxylate

Dimethyl-7-oxabicyclo[2.2.1]hept-5-ene exo,exo-2,3-dicarboxylate (1) was prepared by Fisher esterification of 7-oxabicyclo[2.2.1]-hept-5-ene exo-2,3-dicarboxylic anhydride (2) in methanol. The colorless plates obtained were characterized by FT-IR, ¹H- and ¹³C-NMR, TGA-DSC, and single crystal X-ray diffraction. The material crystallizes in space group P2₁/c, with a = 9.2375(14) Å, b = 12.8757(18) Å, c = 9.4608(15) Å, β = 115.327(3)°, V = 1017.1(3) Å³, and Z = 4. Chains of hydrogen-bonded molecules along the c-axis interact in the b direction to form layers parallel to the bc plane.