No abstract

No abstract

This study has established the feasibility of measuring perilymph lidocaine levels after iontophoresis for local tympanic anesthesia in the rabbit model. A subsequent study may now be performed to produce a valid, dose-response curve correlating perilymph lidocaine levels and cochlear responses. In this manner the effects of and safety of lidocaine iontophoresis for tympanic anesthesia can be determined with certainty. After intravenous sedation, eight rabbits underwent iontophoresis followed by diagnostic vestibulotomies. Perilymph samples were taken and analyzed for lidocaine levels. Significant amounts of perilymph lidocaine were found in both the intact and perforated tympanic membrane groups. In the perforated tympanic membrane group, the perilymph lidocaine level was eight times that of the intact tympanic membrane group. Future studies to determine the dose-response relationship of perilymph lidocaine to cochlear responses are now possible. Thus, the safety of lidocaine iontophoresis and the degree of inner ear toxicity of lidocaine can be established quantitatively.

No abstract

No abstract

No abstract

Ultraperformance liquid chromatography (UPLC) and ion mobility (IM) spectrometry were interfaced with mass spectrometry (MS) and tandem mass spectrometry (MS/MS) to characterize a complex nonionic surfactant mixture. The surfactant was composed of a glycerol core, functionalized with poly(ethylene oxide) units (PEO n ) that were partially esterified by caprylic and/or capric acid. Reversed-phase UPLC classified the blend based on polarity into four groups of eluates, corresponding to compounds with zero, one, two, or three fatty acid residues. Additional separation within each eluate group was achieved according to the length of the fatty acid chains. Coeluting molecules of similar polarity were dispersed in the gas phase by their collision cross section in the IM dimension. Performed in series, UPLC and IM allowed for the separation and detection of several isomeric and isobaric blend constituents, thereby enabling their isolation for conclusive MS/MS analysis to confirm or elucidate their primary structures and architectures (overall four-dimensional, 4D, characterization).

No abstract