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Prepare serial dilutions of stock level A into separate headspace vials. Cap several BLANK vials in advance before working with PFMD to ensure a tracer free backgroundthe blanks are free of PFT. Use a cemented needle syringe from SGE Corp. (not a plastic-tip pipettor) to add the specified levels (Table 2) of stock solution A to 20 mL crimp-top magnetic cap headspace vials by injecting through the septum. Use the high precision 1 µL analytical syringe to accurately measure small volumes. Move plunger VERY slowly while drawing and dispensing the solution. You might not be able to see a drop forming at the tip of the needle. Just stay in the vial for a few moments to ensure the entire injection has evaporated into the vial.
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