in accordance with fig1 there is shown chromatographic column 10 which contains any suitable packing or partitioning material carrier fluid is introduced through line 12 which communicates with a first inlet port 14 of a sample valve 16 the carrier fluid can be either a gas or a liquid depending upon the particular packing material and the desired separation a sample fluid to be analyzed is introduced through line 18 which communicates with inlet port 20 of valve 16 line 22 leads from sample port 24 to the inlet of column 10 line 26 extends from the outlet of column 10 to the first inlet of a detector 28 a portion of the carrier fluid is directed through line 30 to a second inlet of detector 28 as is well known in the art detector 28 can be any suitable instrument which is capable of providing an output signal that is representative of differences in composition of the two fluids passed thereto sample valve 16 is employed to introduce predetermined volumes of samples selectively to the inlet of column 10 this is accomplished by means of a sample loop 32 which extends between ports 34 and 36 the volume of sample loop 32 is selected in accordance with the desired volume of sample to be introduced into the valve when the valve is in the position illustrated the ports are connected in the direction shown by the solid lines carrier fluid thus flows from conduit 12 to conduit 22 sample material flows from conduit 18 through sample loop 32 and is vented through conduit 38 which communicates with port 40 when the sample valve is actuated the ports are connected in the direction shown.