Abstract: Nitrofurantoin particulates comprising discrete particulates of nitrofurantoin wherein:(a) said particulates are larger than about 200 mesh size; and(b) the BET surface area of said particulates is at least about 0.2 M.sup.2 /g.Preferably, the surface of said particulates consists essentially of nitrofurantoin monohydrate. Also preferably, said particulates comprise at least about 5%, more preferably at least about 50% of nitrofurantoin monohydrate. Preferred compositions of this invention comprise these nitrofurantoin particulates in an aqueous suspension. The nitrofurantoin particulates of this invention are highly efficacious for the delivery of nitrofurantoin in oral dosage forms.

Abstract: The present invention involves a dual column chromatographic apparatus with column switching capability that is useful in any pressurized fluid chromatography system. The apparatus has at least a first and second chromatographic column, a detector, a fluid conveyance system having a multivalve arrangement, pressurizable fluid conduit assembly, and a controller.The columns are adapted for containing stationary phase or packing for separation of a multicomponent sample into one or more components. The multi-valve arrangement has a plurality of multi-port, multi-modal valves and can include an ingress-egress valve; a guard pre-column valve; detector isolation valve; a set of four, four-port, multi-modal valves; or a set of two four-port, multi-modal valves and one six-port, multi-modal valve or a first valve set and a second valve set. The two chromatographic columns, multi-valve arrangement, and detector are linked for pressurized fluid communication by the pressurized fluid conduit assembly.