A peg board hook, for insertion into a peg board, the peg board hook includes two tangs, each tang configured complementary, such that tangs from adjacent peg board hooks can be inserted into the same hole. The prefilter, positioned upstream of the system inlet, reduces the presence of non-specific binding species that enter the system, thereby extending the yield, capacity and lifetime of the system. The housing is preferably the size of a standard computer tower. These labels can be attached to any target molecule or particle, resulting in more highly nonlinear-optically active targets.