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