Improving the Cleanliness of DBS Extracts using the Ostro Pass-through 96-well Sample Preparation Plate and Single Step Method

INT RODUCT ION Dried blood spot (DBS) analysis has been rapidly gaining momentum in the pharmaceutical industry. Economic and ethical issues surrounding laboratory animal usage and cost associated with shipping and storing biological samples has made DBS analysis an attractive option. DBS analysis can generate high analyte recoveries. However, this technique does little to eliminate endogenous interferences. Interferences, in particular residual phospholipids (PLs), are a major source of concern in bioanalysis. PLs build up in LC-MS/MS systems and are one of the major causes of matrix effects. Amongst other problems, matrix effects alter mass spectrometry response in an unpredictable manner, decrease method robustness, and add to method variability. The OstroTM Pass-through 96-well Sample Preparation Plate can be used to eliminate greater than 99% of residual PLs. The Ostro Pass-through 96-well Plate further simplifies the DBS extraction process through the use of 96-well format plates which simultaneously extract analytes, reduce PLs and filter out the spot. DBS punches can be extracted in-well, diluted, and directly injected onto an LC-MS/MS system. This novel method significantly reduces sample preparation time and eliminates potential analyte losses due to extract transfer, dry down, and reconstitution. In this work, whole blood samples containing risperidone, its hydroxylated metabolite, 9-OH risperidone, and the internal standard, clozapine (Figure 1) were extracted in both the traditional manner and in-well using the Ostro Pass-through 96-well Plate.