Quantitative analysis of antiretroviral drugs in lysates of peripheral blood mononuclear cells using MALDI-triple quadrupole mass spectrometry.

We report here on the use of a prototype matrix-assisted laser desorption/ionization (MALDI)-triple quadrupole mass spectrometer for quantitative analysis of six antiretroviral drugs in lysates of peripheral blood mononuclear cells (PBMC). Of the five investigated MALDI matrixes, 2,5-dihydroxybenzoic acid (DHB) and the novel 7-hydroxy-4-(trifluoromethyl)coumarin (HFMC) showed the broadest application ranges for the antiretroviral drugs. For DHB, the mean relative errors ranged from 8.3 (ritonavir) to 4.3% (saquinavir). The mean precisions (CV) ranged from 17.3 (nevirapine) to 10.8% (saquinavir). The obtained lower limits of quantitation (LLOQ) readily allow clinical applications using just 1 million PBMC from HIV-infected patients under therapy. The new matrix HFMC was used for quantitative analysis of the HIV protease inhibitor indinavir using a stainless steel target plate as well as a target plate with a novel, strongly hydrophobic fluoropolymer coating. Using the coated target plate, the mean relative error improved from 10.1 to 4.6%, the mean precision from 33.9 to 9.9% CV, and the LLOQ from 16 to 1 fmol. In addition, the measurement time for one spot went down from 6 to only 2.5 s.