The Microsaic 3500 MiD is a fully integrated MS system. It is the size of a standard desktop computer. The 3500 MiD is designed to readily integrate with existing HPLC equipment with no extra footprint. The 3500 MiD can be used for on-line reaction monitoring in a fume-hood. Monitoring batch reactions in real time provides data that can be acted upon to maximize yield and/or minimize impurities. The system is portable with modular plug and play components for better flexibility.