Drug screening using microextraction in a packed syringe (MEPS)/mass spectrometry utilizing monolithic-, polymer-, and silica-based sorbents

Micro extraction in packed syringe (MEPS) has been evaluated for drug and metabolites screening online with mass spectrometric detection. In this study, silica based (C-8), polymer based (ENV+), and a methacrylate based organic monolith were used as sorbents for MEPS. Monolithic material has shown to be an effective chromatographic support for the separation of several classes of compounds. In this study, the focus is subdivided into three parts: 1) Using MEPS for drugs and metabolites screening, 2) Preparation of a monolithic material in situ in a syringe, and 3) Comparison of the monolith, ENV+ , and C-8 as sorbent material. The synthesis of the monolithic material was by radical polymerization of glycidyl methacrylate (GMA), ethylene glycol dimethacrylate (EGDMA), and butyl methacrylate (BMA) in porogenic solvent 1-dodecanol and cyclohexanol. An 8 mu L of the synthesized material was drawn into a 250 mu L syringe and thermally polymerized at 57 degrees C for 24 h. Individual syringes containing the monolithic material, ENV + (polystyrene) and C-8, were prepared and used for screening ropivacaine, lidocaine in plasma, and lidocaine metabolites (glycylxylidide, monoethylglycylxylidide, and 3-OH-lidocaine) in urine samples. Our results showed that all three sorbents could be used for effective and fast screening for analytes in complex matrices, such as plasma and urine. However, for this study, the ENV+ material performed better than C-8 , followed by the monolithic sorbent.