A highly sensitive method was developed and validated to allow monkey plasma samples, potentially containing Bacillus anthracis (B.anthracis) spores, to be filtered and shipped from the testing site to the bioanalytical laboratory, MicroConstants, for analysis of Solithromycin (SOLI), a novel fluoroketolide antibiotic, and two of its metabolites. In the presence of plasma, the compounds were found to bind to the filtration devices typically used to remove B.anthracis spores. This was resolved by using acetonitrile to precipitate the samples prior to filtration. During development, SOLI was found to be unstable in acetonitrile when manipulated or stored in various container systems. A stabilizing solution was developed, allowing acetonitrile to be present while preventing non-specific binding to the filter and preserving SOLI and its two metabolites during sample processing, storage and shipment. B.anthracis free samples were then shipped to MicroConstants for further processing and quantitation. The entire process was validated between the sites to ensure safety from anthrax, as well as accurate and precise bioanalytical data.