Phenol-selective mass spectrometric analysis of jet fuel.

Bromobenzyl compounds react selectively with phenols via the Williamson ether synthesis. An imidazolium charge-tagged bromobenzyl compound can be used to reveal phenol impurities in jet fuel by analysis via electrospray ionization mass spectrometry. The complex matrix as revealed by Cold EI GC/MS analysis is reduced to a few simple sets of compounds in the charge-tagged ESI mass spectrum, primarily substituted phenols and thiols. Examination of jet fuels treated by different refinery methods reveals the efficacy of these approaches in removing these contaminants.

Reactive metallocene cations as sensitive indicators of gas-phase oxygen and water.

Analysis of highly reactive compounds at very low concentration in solution using electrospray ionization mass spectrometry requires the use of exhaustively purified solvents. It has generally been assumed that desolvation gas purity needs to be similarly high, and so most chemists working in this space have relied upon high purity gas. However, the increasing competitiveness of nitrogen generators, which provide gas purity levels that vary inversely with flow rate, prompted an investigation of the effect of gas-phase oxygen on the speciation of ions. The most reactive species studied, the reduced titanium complex [Cp2Ti(NCMe)2]+[ZnCl3]- and the olefin polymerization pre-catalyst [Cp2Zr(µ-Me)2AlMe2]+[B(C6F5)4]-, only exhibited detectable oxidation when they were rendered coordinatively unsaturated through in-source fragmentation. Computational chemistry allowed us to find the most plausible pathways for the observed chemistry in the absence of observed intermediates. The results provide insight into the gas-phase oxidation or hydrolysis of these reactive species.

Development and Field Validation of Lidocaine-Loaded Castration Bands for Bovine Pain Mitigation.

Castration is among the most common management procedures performed in the dairy and beef cattle industries and is mainly performed by surgery or elastic banding. Despite the various benefits of castration, all methods produce pain and distress. Castration by banding is simple, inexpensive, produces fewer complications, and can be performed in a high-throughput manner. Because lidocaine, a local anesthetic, can be delivered to trauma sites topically, we have formulated lidocaine-loaded castration bands (LLBs) to deliver local pain relief to calves during banded castration. The initial lidocaine content of three band types developed was between 80 and 200 mg per band. The transfer kinetics of lidocaine into tissue was determined in vitro, indicating a rapid release for the first 30 min, followed by a slow release lasting at least 48 h. Furthermore, the lidocaine delivery and pain mitigation effects of these LLBs were compared to standard lidocaine injections in vivo. Field studies indicated that LLBs performed at least as well as lidocaine injections for short-term lidocaine delivery into tissues and pain mitigation. Moreover, LLBs significantly outperformed lidocaine injections for long-term delivery and pain mitigation. The concentrations of lidocaine in the LLB-treated tissue samples were generally in the range of 0.5-3.5 mg of lidocaine per gram of tissue and were overall highest after 6 h. Lidocaine-loaded elastration bands deliver therapeutic quantities of lidocaine into scrotal tissues over a period of at least seven days in cattle. This approach would provide long-term pain mitigation to the animals and, by avoiding surgery or the administration of injections, would also decrease the time and handling costs for the producer.

Quadrupole excitation of ions in linear quadrupole ion traps with added octopole fields.

Modeling and experimental studies of quadrupole excitation of ions in linear quadrupole traps with added octopole fields are described. An approximate solution to the equations of motion of ions trapped in a quadrupole with added octopole and dodecapole fields, with quadrupole excitation and damping is given. The solutions give the steady-state or stationary amplitudes of oscillation with different excitation frequencies. Trajectory calculations of the oscillation amplitudes are also presented. The calculations show that there can be large changes in the amplitude of ion oscillation with small changes in excitation frequency, on both the low and high-frequency sides of a resonance. Results of experiments with quadrupole excitation of reserpine ions in linear quadrupole traps with 2.0%, 2.6%, and 4.0% added octopole fields are given. It is found that as the excitation frequency is changed, two resonances are generally observed, which are attributed to the motion in the x and y directions. The two resonances can have quite different intensities. Sudden jumps or sharp sided resonances are not observed, although in some cases asymmetric resonances are seen. The calculated frequency differences between the two resonances are in approximate agreement with the experiments.

Electron ionization mass spectrometric analysis of air- and moisture-sensitive organometallic compounds.

Electron ionization (EI) is a reliable mass spectrometric method for the analysis of the vast majority of thermally stable and volatile compounds. In direct EI-MS, the sample is placed into the probe and introduced to the source. For air- and moisture-sensitive organometallic complexes, the sample introduction step is critical. A small quantity must be briefly exposed to the atmosphere, during which time decomposition can occur. Here we present a simple tool that allows convenient analysis of air- and moisture-sensitive organometallic species by direct probe methods: a small purge-able glove chamber affixed to the front end of the mass spectrometer. Using the upgraded mass spectrometer, we successfully characterized a series of air- and moisture-sensitive organometallic complexes, ranging from mildly to very air-sensitive.