( Gargi Choudhary Tania A. Sa...)Sensitivity and Quantitation using a Finnigan LCQ Deca XP Plus Ion Trap Mass Spectrometer

Gargi Choudhary, Tania A. Sasaki, and Julian J. Phillips, Thermo Electron Corporation, San Jose, CA

Chromatography and Mass Spectrometry Application Report

Introduction
Ion trap mass spectrometry is widely recognized for solving analytical problems requiring high sensitivity MSⁿ such as for structural elucidation and identification of unknowns in complex matrices. Furthermore, its full-scan sensitivity is responsible for its utility in screening analysis. Although the popularity of ion trap mass spectrometry is concentrated mostly on qualitative analyses, these mass spectrometers perform well for quantitative analyses as well.

Goal
In this report we have used a full-scan MS/MS quantitative assay of antipsychotic drug alprazolam and its analog temazepam spiked in protein precipitated bovine plasma to evaluate the quantitative abilities of a Finnigan LCQ Deca XP Plus ion trap mass spectrometer.

Experimental

Compounds
Analytes: Temazepam and alprazolam Internal Standard (ISTD): alprazolam-d5

Sample preparation
The proteins from a plasma matrix were precipitated by the addition of an equal volume of 80:20 acetonitrile: methanol containing 1% acetic acid. The plasma sample was then centrifuged for 5 minutes and supernatant decanted. The supernatant was spiked with appropriate levels of analytes and the internal standard.

Sample solutions
Standard samples: 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 40, 100, 200, 400, 1000 pg/μL
Internal Standard (ISTD): 10 pg/μL

HPLC
HPLC system: Surveyor MS pump with Surveyor autosampler
Column: 20 2.1 mm i.d. packed with 5 μm AQUASIL
C18 stationary phase (Thermo Ele
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