Accurate quantitation of glutathione in cell lysates through surface-assisted laser desorption/ionization mass spectrometry using gold nanoparticles

We developed a method for the determination of three aminothiols-cysteine (Cys), glutathione (GSH), and homocysteine (HCys)-using surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) The analytes were first captured using the unmodified 14-nm Au NPs; N-2-mercaptopropionylglycine (MPG) modified Au NPs served as internal standard was sequentially added and then the sample was analyzed using SALDI-MS. This approach provided good quantitative linearity of the three analytes (R2= ca. 0.99), with good reproducibility (relative standard deviations:<10%), in the analyses of GSH in the lysates of human red blood cells and MCF-7 cancer breast cells in the presence and absence of the anti-inflammatory drug sulfasalazine. The internal standard SALDI-MS approach provides simplicity, accuracy, and precision to the determination of GSH in cells under drug invasion, to open an avenue for SALDI-MS to be used for the precise quantitative determination of a variety of analytes.