Protein precipitation for the analysis of a drug cocktail in plasma by LC-ESI-MS.
Three protein precipitation (PP) procedures with acetonitrile (ACN), perchloric acid (PA) and trichloroacetic acid (TCA) were investigated for the analysis of a drug cocktail from human plasma samples containing three pharmaceutical compounds and their primary metabolites. For this purpose, a capillary liquid chromatography-electrospray ionisation-mass spectrometry (LC-ESI-MS) method was developed for the simultaneous analysis of the six tested compounds in less than 6 min. Matrix effect was tested for each PP procedure by means of a post-column infusion system. The three PP techniques were found effective in removing proteins from human plasma and were fully compatible with capillary LC-ESI-MS analysis. However, with acid precipitations, low analyte recovery and a high variability, probably due to analyte coprecipitation, were obtained. Finally, ACN was found to be the most effective PP technique with a recovery higher than 80% and CV inferior to 6%.
Souverain
S
S
Laboratory of Analytical Pharmaceutical Chemistry, School of Pharmacy, University of Geneva, 20 bvd d'Yvoy, 1211 Geneva 4, Switzerland.
Rudaz
S
S
Veuthey
J-L
JL
D001798:Blood Proteins / Q000032:analysis* / Q000378:metabolism; D011232:Chemical Precipitation; D002853:Chromatography, Liquid / Q000379:methods; D006801:Humans; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
D001798:Blood Proteins