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, glutathione (GSH), and homocysteine--using surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS). The analytes were first captured using the unmodified 14-nm gold nanoparticles; N-2-mercaptopropionylglycine-modified gold nanoparticles serving as internal standard were sequentially added, and then the sample was analyzed using SALDI-MS. This approach provided good quantitative linearity of the three analytes (R(2) = approximately 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. From the clinical editor: This paper reports the development of a surface assisted laser desorption/ionization mass spectrometry method to precisely determine aminothiols-cysteine (Cys), glutathione (GSH), and homocysteine (HCys).