Abstract--Samples of Na-saturated, Upton montmorillonite were prepared with different contents of water (H20 or D20) by: (1) adsorption of water from the vapor phase at a specific value of p/p*, the relative humidity, (2) adsorption of water from the vapor phase at p/p* = 1.0 followed by desorption of the water into the vapor phase at a specific p/p* < 1.0, and (3) adsorption of water from the liquid phase followed by desorption of the water into the vapor phase at a specific p/p* < 1.0. Water adsorbed initially from the vapor phase was called V-adsorbed water, and water adsorbed initially from the liquid phase was called L-adsorbed water. The water contents of these samples were determined by gravimetric analysis, the c-axis spacings by X-ray powder diffraction, the O-D stretching frequencies by IR spectroscopy, and the heats of immersion by differential microcalorimetry. No difference was found between V-adsorbed and L-adsorbed water; however, if the final water content was established by adsorption, the system was in a different state than if the final water content was established by desorption. In particular, hysteresis was observed in the following properties: the relative humidity of the adsorbed water, the O-D stretching frequency in this water, and the degree of order in the stacking of the clay layers. The only property that did not exhibit hysteresis was the heat of immersion. Apparently, hysteresis occurred because the orderliness of the system was not reversible, and, thus, any property that depended on orderliness was hysteretic.

A mass spectrometric method is presented for the identification of compounds that contain the aliphatic or aromatic N-oxide functional group. This method utilizes gas-phase ion/molecule reactions of tri(dimethylamino)borane (TDMAB), which rapidly derivatizes protonated aliphatic and aromatic tertiary N-oxides, amides, and some amines via loss of dimethylamine in a Fourier transform ion cyclotron resonance mass spectrometer. The mechanism involves proton transfer from the protonated analyte to the borane, followed by addition of the analyte to the boron center and elimination of dimethylamine. The derivatized analytes are readily identified on the basis of their m/z value which is 98 Th (thomson) greater than that of the protonated analyte, and the characteristic boron isotope patterns. SORI-CAD of the product ions (adduct-(CH3)2NH) yields different fragment ions for aliphatic tertiary N-oxides, aromatic tertiary N-oxides, amides, and pyridines. Therefore, these analytes can be identified based on their characteristic fragment ions. This method was tested by examining two drug samples, Olanzapine and Olanzapine-4' N-oxide.

The gas-phase reactions of ClMn(H2O)+ with a variety of volatile and nonvolatile, saturated and unsaturated hydrocarbons have been examined by using Fourier transform ion cyclotron resonance mass spectrometry (FT/ICR). The ClMn(H2O)+ ion reacts rapidly by exclusive H2O ligand displacement with all the hydrocarbons studied, including highly branched alkanes that usually fragment upon ionization. These observations are rationalized on the basis of the electronic structure of ClMn+. Collision-activated dissociation of the product ions provides structural information which promises to allow the distinction and structural characterization of isomeric hydrocarbons. These findings suggest that the ClMn(H2O)+ ion is a highly promising chemical ionization reagent for mass spectrometric characterization of hydrocarbons, including those that commonly exist in petroleum