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Automated laboratory chromatography injectors are part of the autosamplers of gas chromatography or high-pressure liquid chromatography units. Sample delivery systems are designed to interface with gas-liquid chromatography systems or high-pressure liquid chromatography systems to introduce gas, liquid or solid phase micro extraction samples into the sample loop (mobile phase) of the system in the smallest volume possible so that the sample enters the stationary phase column as a homogeneous, low-volume plug. Automated injectors are designed to inject consistently sized samples at a fast rate with high reproducibility of results so that many samples (several to hundreds) can be analyzed in a short amount of time. They usually have automated injectors consisting of an automated arm with a microsyringe at the bottom that is positioned above a tray holding the sample vials. The microsyringe may be interchangeable to handle different sized samples. The microsyringe is lowered by the automatically controlled arm through a septum covering the top of the sample vial, and after withdrawing a sample, it is raised and positioned to inject the sample into the chromatography injector port. Microprocessor-controlled automatic injectors can sequentially inject several samples for batch processing, automatically flushing the sample loop between each sample to minimize carryover. Some automated chromatography injectors are designed to deliver samples into the chromatography system at a controlled volume, injection speed, temperature, pressure, and lag time between samples. Automated injectors are used when consistent sample size and rapid introduction of samples are needed for a large number of samples; they offer minimum error in reproducibility of results when compared with manual injectors.
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