An autosampler is an instrument which is used in a variety of different laboratory applications, especially gas-liquid chromatography, where it is used (as the name implies) to automatically bring in a sample into the inlets of the equipment being employed in a given test. While it is possible to manually insert samples with many instruments, this is no longer the normal practice, since autosamplers offer a more efficient and reproducible method.
Autosamplers might be classified by their capacity, such as autosamplers as opposed to auto-injectors; the latter instrument can be capable of running more than one sample at once. Robotic instruments offer another category of autosampler, with rotating/SCARA programs being among the most widely used.
In gas-liquid chromatography, the column inlet (or injector) provides for the introduction of samples into a continuous flow of carrier gasoline. Common inlet types are the split/splitless injectors, on-column inlets, PTV injections, the gas source inlet (also called a gas switching valve), purge and trap systems plus SPME (solid phase micro extraction) systems. In the split/splitless injector, the sample is introduced to a warmed chamber using a syringe.
With an on-column inlet, the sample is presented in its entirety without the use of temperature. PTV injectors introduce the small sample through a heated liner at a managed rate. In the gas source inlet method, the sample is placed into the gas stream from collection bottles, a method which allows samples to become introduced without interrupting the company gas flow.
Purge and snare autosampler systems involve bubbling an inert gas through aqueous examples, purging insoluble volatile compounds from your matrix. These volatile compounds are usually then trapped in an absorbent line which is then heated – the volatiles are directed into the carrier stream. Solid phase micro extraction (SPME)is a more economical alternative to purge and trap systems which provides higher ease of use and a lower cost.
The type of automated sampling system used depends largely on the specific application; in fuel chromatography alone, there are two various kinds of columns used – with the different types of autosampler being more appropriate for one or maybe the other. There are packed columns (usually made of glass or stainless steel and containing an inert, solid plus highly granular material which is coated with a liquid or solid fixed phase).
The other type are capillary columns; these columns feature a very small internal diameter, with the inside of the line being coated with the phase. Some other capillary columns are made with a semi-solid construction and parallel micropores; this style allows for great flexibility, so a long column can be wound into a tight coil which takes up much less room.
While it is gas plus liquid chromatography which often first spring to mind when discussing different types of autosampler, you can find samplers used in many different applications in the life sciences to geological research, the pharmaceutical industry, water high quality testing and nearly every other app in the materials and life sciences as well as quality control testing of most types. These instruments allow laboratories to handle higher sample throughputs whilst increasing reproducibility and efficiency.