Analysis of the HOOO torsional potential

Torsional levels of cis and trans HOOO and DOOO, observed previously via infrared action spectroscopy [E. L. Derro, T. D. Sechler, C. Murray, and M. I. Lester, J. Chem. Phys. 128, 244313 (2008)], have been used in conjunction with ab initio theory to obtain a torsional potential energy surface for the hydrotrioxy radical. High level electronic structure calculations based on the equation-of-motion coupled-cluster method for ionized states (EOMIP-CCSD) are utilized to produce a torsional potential. Eigenvalues of the potential are computed by diagonalizing the torsional hamiltonian in a free-rotor basis. Uniform scaling of the theoretical potential by a factor of 1.35 yields vibrational frequencies in good agreement with the experiment, and allows prediction of the barrier height to isomerization of ～340 cm(-1) and relative stability of trans-HOOO with respect to cis-HOOO of ～70 cm(-1). Examination of the optimized nuclear coordinates with respect to the torsional angle, suggests that the central O-O bond length is strongly coupled to the torsion and is important in determining the relative stabilities of the two conformers. The scaled potential is then used to determine the torsional contribution to the partition function for atmospheric modeling of HOOO.     

Speciation and detection of organotins from PVC pipe by micro‐liquid chromatography–electrospray–ion trap mass spectrometry

This paper describes the application of a micro‐liquid chromatography–electrospray–ion trap mass spectrometry (µ‐LC–ES–ITMS) method for separation and detection of organotin compounds leached from potable‐water polyvinyl chloride (PVC) pipe. Dibutyltin (DBT) is added as a heat stabilizer to PVC. DBT was determined in 1 l water samples that had remained static in PVC pipes over several days (totaling 96 h). Other organotin compounds in the leachate were screened for, by using µ‐LC–ES–ITMS. An initial level of approximately 1 µgl^?1 of DBT resulted within 24 h, with a subsequent drop and then a rise in DBT levels over the next 96 h to 0.8 µgl^?1. Published in 2001 by John Wiley & Sons, Ltd.     

Determination of organotins in water by micro liquid chromatography–electrospray/ion trap mass spectrometry

Due to the varying toxicity the species of organotins in their widespread applications, it is important for analytical methods to address their speciation. Traditional methods call for the hydrolysis and subsequent derivatization of the organotins before analysis. These methods can be time‐consuming, derivatization can be incomplete and high levels of background interference produce difficulties in identification and quantification. The use is described of a non‐derivatization and non‐hydrolysis micro‐liquid chromatography–electrospray/ion trap mass spectrometry for separation and detection of the organotins. Copyright © 1999 John Wiley & Sons, Ltd.