The analysis of dried blood spots (DBS) for the determination of drug concentrations in whole blood is well known.^1,2 However, minimal work has been done to apply this technique for fluids other than whole blood. Traditional analyses on other fluids, such as synovial fluid, tears, or cerebral spinal fluid (CSF) have been cumbersome due to the limitation on sample volume. DBS techniques have provided an alternative collection and extraction method to traditional forms of analysis of low volume assays due to the much smaller volume requirement. Because collected samples are stored at ambient temperatures, this technique can be applied when studies are conducted in areas that do not have access to the low temperature freezers required to store traditional matrices.

Here we report on a simple DBS preparation method coupled with HPLC/MS/MS to provide an accurate and precise assay for the determination of Indomethacin from human urine, human saliva, human CSF, human tears, and mini-pig synovial fluid.