extract aliquots from these sealed vials the autosampler is modified to use a stainless steel 12 inch 18 gauge luer hub needle kontes h90018 0012 these modifications include an additional set screw for the probe and an acrylic plate with precisely machined holes that hold the sample vials in place when the probe exits the sample vial in order to maintain a consistent flow of sample through the sample loop the sealed vials have to be vented this venting is done by machining an aluminum block with two holes corresponding to the outer diameter of the 18 gauge needle and a stainless steel 22 gauge vent needle the vent needle assembly is attached just below the autosampler probe with a set screw on the 18 gauge needle the 22 gauge needle is fastened with another set screw all connections within the manifold are made with zero dead volume flange fittings with 1 4 28 thread connectors tefzel tees and luer lock connections for the autoanalysis tubing as seen from fig5 the peak heights of the samples and standards are corrected for reagent blank fluorescence by averaging the peak heights of two reagent injections into diw which has no dom the samples.