Acuity uplc

Paclitaxel concentration in the brain and plasma of mice (n = 4) was determined by LC-MS using a Waters Micromass Quattro Premier coupled to a Waters Acuity UPLC. Gradient chromatography was achieved with an acetonitrile-water/0.05% formic acid mobile phase and a Supelco Ascentic Express RP C18 (50 x 2.1 mm, 2.7 µm) column. Each whole brain was homogenized in aqueous buffer (3-fold mass/volume ratio), and the resulting homogenates were then protein-precipitated with acetonitrile (3-fold volume/volume ratio). Plasma samples were protein-precipitated with acetonitrile (2-fold volume/volume ratio). Quantitation was performed relative to spiked calibration standards prepared in blank mouse plasma (paclitaxel range: 1–10,000 ng/ml) and brain homogenate (paclitaxel range: 5-10,000 ng/g tissue).

Serum 25(OH)D concentrations were determined by the HPLC-MS/MS method on a Waters Acuity UPLC (Triple Quadrupole) TQD^® System using a Pentafluorophenyl (PFP) column following supported liquid extraction (SLE). Laboratory intra- and inter-assay coefficients of variation (CV) were 5.6% and 7.8%, respectively. Calcium, albumin, and PTH concentrations were measured using Abbott Architect kits. Serum calcium was measured by using an endpoint spectrophotometric reaction based on the o-cresolphthalein complexone methodology, and serum albumin was measured by using an endpoint spectrophotometric reaction based on the bromocresol green solution dye binding methodology. Serum calcium concentrations were adjusted for albumin concentrations. Plasma intact PTH was measured by in vitro chemiluminescent microparticle immunoassay (CMIA). The manufacturer’s quoted inter-assay CV for calcium was <3%, for albumin <3.8%, and for PTH 4%.