Development and validation of an LC/MS/MS procedure for the quantification of endogenous myo-inositol concentrations in rat brain tissue homogenates.

myo-Inositol is being investigated as a biomarker to monitor disease states involving the central nervous system. We have developed and validated a quantitative method to study endogenous myo-inositol metabolism in rat brain tissue. Tissue samples were homogenized, and their myo-inositol content was determined using spiked calibration curves and mass spectrometry. The assay was validated on an LC/MS/MS platform, and specificity was evaluated using accurate mass measurements. A novel chiral LC/MS/MS method was also developed to resolve myo-inositol from other endogenous inositol epimers and confirm the selectivity of the quantitative procedure. The validated method is selective, convenient, precise (<15% RSD), accurate (<15% RE), and sensitive over a linear range of 0.100-100 microg/mL. This method could potentially be used as an instrument for monitoring pathological conditions related to psychotherapeutics, as well as a tool for screening curative pharmaceuticals for efficacy.