Sample injector for a liquid chromatograph

Abstract

A sample injector for a liquid chromatograph comprises a high pressure syringe unit, a sample intake unit having a needle which can be introduced into a sample container as well as into a seat, and a 6/2-way valve. The high pressure syringe unitis designed as a piston pump with a pump head and a piston which is driven by a motor via a drive mechanism. Pressurized liquid from a solvent delivery system (SDS) can enter the pump head through an inlet port and flow along the piston to an outlet port. When sample is to be injected into a chromatographic column, the 6/2-way vale is first switched to a position dotted whereby the pressurized solvent is shunted from the high pressure syringe unit to the column. The needle is then introduced into the container and the piston (5) is retracted to a position which draws in the desired volume of sample. Thereafter, the valve is switched back to its original position so that solvent delivered from the solvent delivery system passes through the high pressure syringe unit and can transport the sample to the column. Sincethe solvent flushes the entire syringe unit, it is ensured that no sample residues remain in the syringe unit which would otherwise impair the chromatographic measuring process.

Dependencies are inferred from the claim text.