Reuse of filter plates for elution of dried blood spot samples in neonatal assays.

Millipore MultiScreenTM filter plates are used for elution of dried blood spot samples in neonatal screening assays. A significant concern with the use of these plates is their cost. In this study we have evaluated the practice of reusing the filter plates in the Bio-Rad PKU and total galactose neonatal assays. All wells of the test plates used in the recovery study above were washed for a fifth time and then filled with DBS using the zero standard. An unused plate filled with zero standard DBS was used as a control. DBS were eluted and tested according to assay protocols. Results of the fifth run with zero standard on the used plates were compared to zero standard eluted on the unused plate. MATERIALS AND METHODS RESULTS Cleaning procedure Physical damage All dried blood spots (DBS) were removed from the wells by shaking or tapping the plate over an appropriate biohazard trash bin. The plates were rinsed under running tap water, ensuring the plates were filled and emptied 3 times. The plates were soaked for four hours by immersing in distilled or deionized water, ensuring that all wells were filled with water. Excess water was shaken out, blotted on paper towel, and dried in a 37 C incubator overnight.