Predetector reservoir for chromatographic analysis instrument

An analytical instrument for the determination of at least the elemental carbon, hydrogen and nitrogen in a sample, comprising:

• means defining a combustion chamber having means for sample introduction, means for oxygen gas introduction, means for introduction of an inert carrier gas at a flow rate R and means for heating the sample to a temperature effective for essentially complete combustion of the sample to produce a mixed combustion product;
• gas chromatographic means for separating the mixed combustion product into a water phase, a sulfur dioxide phase, a carbon dioxide phase and a nitrogen phase;
• detector means for detecting a respective representative property of the water, the sulfur dioxide, the carbon dioxide and the nitrogen;
• and
• conduit means for fluid flow between the outlet end of a selected gas chromatographic means and the inlet end of a selected detector means, the conduit means directly connecting the gas chromatography column with the detector, said conduit means having an effective volume, at the rate of carrier gas flow, at least sufficient to contain the phase having the greatest volume which is being detected by the selected detector means.

A method for chemical analysis of a sample in an instrument comprising a gas chromatography column having an inlet end and an outlet end and a detector having an inlet end and an outlet end, comprising the steps of:

• (a) introducing at least a portion of the sample in the form of a mixture of gases into the inlet end of the gas chromatography column and passing the mixture of gases through the column in a carrier gas having a flow rate R so as to separate at least one component of interest from the mixture of gases;
• (b) passing the component of interest into a conduit directly extending from the outlet end of the gas chromatography column to the inlet end of the detector said conduit having an effective volume, at the rate of carrier gas flow, at least sufficient to contain the constituent to be detected plus the volume of associated carrier gas;
• (c) passing the component of interest through the conduit in the carrier gas having the flow rate R;
• (d) passing the component of interest to the inlet end of the detector after the essentially complete elution of the component of interest from the gas chromatography column;
• and
• (e) detecting a property of the component of interest.