Methanol-ethanol Mixtures Research Articles

Simultaneous enzymatic determination of methanol and ethanol by flow injection analysis

A differential-kinetic enzymatic method for the resolution of methanol-ethanol mixtures based on the use of a reactor containing alcohol oxidase immobilized on controlled-pore glass is proposed. The method also involves the aldehyde/ p-rosaniline/sulfite-coupled reaction and a twofold halting of the flow (in the enzymatic reactor to favor the oxidation reaction and in the detector flow cell to perform kinetic measurements) per sample assayed. The determination range is between 10 and 60 and 10 and 300 μg/ml for methanol and ethanol, respectively. Equations of the calibration curves for the mixtures have been derived where the concentration of each analyte is a function of the absorbance monitored at different stop times in the detector.

Measurement and correlation of vapor-liquid equilibria of ethanol-water-calcium chloride and methanol-ethanol-calcium chloride systems at 25.DEG.C.

The vapor-liquid equilibrium relations of ethanol-water-calcium chloride and methanol-ethanol-calcium chloride systems have been measured by use of a flow-type apparatus at 25°C. The partial pressure data are reported at salt concentrations of 0, 5, 10, and 15% in mass.The present vapor-liquid equilibrium data were correlated by an empirical model recently proposed by Hala. It is found that the salting-out and salting-in effects on ethanol-water and methanol-ethanol mixtures by calcium chloride can be illustrated by adjusting the empirical parameter contained in the electrostatic contribution term.

Properties of P-form DNA as revealed by circular dichroism.

AbstractInvestigations of DNA using CD spectroscopy show that the P‐form is available in a wide variety of methanol–ethanol mixtures when the water content is low. Increasing the temperature or the ethanol content of a 95% methanol solution causes DNA to undergo a cooperative transition to the P‐form. However, this transition cannot be reversed on cooling, or on adding methanol. Thus P‐form DNA appears to be stable at high methanol concentrations, but it is usually not observed because the DNA is trapped by a kinetic barrier. P‐form DNA will instantaneously assume the native B‐form on addition of water, confirming earlier reports that P‐form DNA is not strand separated [E. Kay (1976) Biochemistry 15, 5241]. CD spectra extended to 190 nm show that there is no base–base interaction in the P‐form. However, the P‐form is extremely stable to heat denaturation in solvents which promote hydrogen bonding between the base pairs. A number of models that can account for the properties of P‐form DNA are discussed.

Study of Solid Support and Partition Liquid Interactions in Gas Chromatographic Separation of Ethanol-Methanol Mixtures.

Study of Solid Support and Partition Liquid Interactions in Gas Chromatographic Separation of Ethanol-Methanol Mixtures.