Patent ID: 9423386
Filing Date: 2016-08-23
CPC Classification: G01N

Claim Text:
1. A method for detecting a chemical species in an aqueous ionic sample by a detector system, the method comprising: providing, in a vessel, an acidic sample containing an ionic chemical species to be measured wherein a substrate of the species to be formed is ionizable by radiant energy provided by a photoionization detector in the detector system and wherein the vessel has a headspace above the acidic sample; adding a preselected reducing agent to the aqueous sample and forming an ionizable chemical gas species in the aqueous sample whereby the ionizable chemical gas species evolves out of the aqueous sample and into the headspace forming a gas sample; conducting the gas sample containing the ionizable chemical gas species from the headspace of the vessel out of the vessel and through a precolumn wherein the precolumn retains water and other organics of the gas sample in the precolumn while passing the gas sample containing the ionizable chemical gas species through the precolumn; and conducting the gas sample containing the ionizable chemical gas species from the precolumn into one of (1) a photoionization detector or a gas chromatograph having a photoionization detector if the headspace is purged with nitrogen gas prior to performing the adding step, or, (2) an oxygen-retaining column before conducting the gas sample into a photoionization detector or a gas chromatograph having a photoionization detector if the headspace contains oxygen before the adding step is performed, wherein the method is performed without using a liquid nitrogen cold trap.