The invention relates to a process of separating compounds with a small molar mass from compounds having a molar mass less than 1. The imaging system includes a radiation detector array with a right and left edge. A key image reproduced in synchronism with the main image is referred to decide whether the pointer is within a key region. Asynchronous refers to the ability for processing instructions and responses to be transferred by a variety of methods but not solely dependent on direct communications, such as via a store-and-forward mechanism, and can also include server-side push directly to the endpoint and client-side pull from a predetermined rendezvous point.