Work performed with Nacuity Pharmaceuticals
Features Derivatization, Multi-Analyte/Multistate
(Free and Total) Analysis and the
Validation of Endogenous Compounds
AIT Bioscience and Nacuity Pharmaceuticals recently shared their research on the bioanalysis of free and total N-acetylcysteine (NAC, an endogenous compound) and N-acetyl cysteine amide (NACA) in the Journal of Chromatography B. This publication, Quantitation of free and total N-acetylcysteine amide and its metabolite N-acetylcysteine in human plasma using derivatization and electrospray LC-MS/MS, was authored by Brad King, Jennifer Vance and Ronald Shoup from AIT Bioscience along with G. Michael Wall from Nacuity Pharmaceuticals.
The featured method provides quantitation of both the free and total forms of NAC and NACA from a single 25 uL plasma sample. The derivatization also serves as the stabilization procedure to protect free thiols upon blood collection. The use of HILIC phase chromatography provides excellent resolution between the NAC and NACA derivatives. Endogenous NAC is present almost entirely in the oxidized form and shows no interference in the quantitation of free NAC. In the total assay, endogenous NAC is present at levels ranging from 20-60% of LLOQ and is not factored into the reported quantitation.
The methodology presented in this research has supported clinical trials and demonstrated its robustness with greater than 95% and greater than 99% incurred sample reanalysis agreement for NAC and NACA, respectively.