Abstract: A liquid sampling valve for a gas chromatographic analyzer (GCA) has a sampling stem. The stem is substantially cylindrical and has on its surface a sample collecting groove. The stem is movable from a first position in which the groove is in communication with the liquid to be analyzed for collection of same, to a second position in which the liquid collected in the groove is deposited in the GCA for analysis. The stem is also movable to a third position in which the groove is in communication with a cleaning solution capable of cleaning residues, which are left by said liquid to be analyzed, in the groove.

Abstract: An apparatus to measure the concentration of a constituent of a solution containing dissolved gas includes a conduit connectable to a source of the solution. Flow controllers are provided on the conduit, selectively to permit the flow of the solution in the conduit. Pressure regulators are also provided on the conduit to control the pressure of the solution in the conduit, and maintain the pressure in the conduit means at a level sufficiently high to prevent gassification of dissolved gas in the solution, thereby to prevent foaming in the conduit. A gas chromatographic analyser (GCA) is in communication with the conduit via a sampling valve, to permit the flow of discrete samples of solution into the GCA for analysis. The interior of the GCA is maintainable at the same pressure as in the conduit.