Coupling protocol for thin layer chromatography/matrix-assisted laser desorption ionization

Summary This paper reports the investigation and optimization of the thin layer chromatography/matrix-assisted laser desorption/ionization (TLC-MALDI) coupling protocol. The fundamental coupling parameters which influence sensitivity and lateral analyte spreading are extraction solvent selection, extraction time, and pressure. Selection of the solvent is dependent upon its extraction efficiency, which has been correlated with extraction solventR _f value. Maximum extraction efficiency occurs after two minutes for the analyte/solvent system studied. High extraction efficiency solvents cause significant lateral spreading of analyte; up to a three-fold increase in initial analyte spot size. Analyte recovery was found to be limited by the silica gel inter-partice porosity and the solvent extraction efficiency. For maintaining chromatographic resolution and maximizing signal intensity, extraction solvents withR _f values between 0.4 to 0.6 are optimal. The upper analyte recovery limit, using extraction solvents within thisR _f range, is estimated at 22%. Dedicated to Professor Werner Haerdi on the occasion of his 70^th birthday.