Sample preparation system

The utility model provides a sample preparation system. The sample preparation system comprises a plurality of parallel extraction channels, a gas supply unit for supplying gas to each of the sample cells, the gas supply unit comprising: a first supply line; the plurality of parallel second supply pipelines are separated from the first supply pipeline, each second supply pipeline can be in fluid communication with a corresponding extraction channel, and the second supply pipelines are located between the first supply pipeline and the extraction channels when viewed in the flowing direction of the gas; a first flow control device disposed on the first supply line to control the total flow of the gas supplied to the plurality of extraction channels; and a plurality of second flow limiting devices, each second flow limiting device can be arranged on a corresponding one of the second supply pipelines and comprises a resistance providing structure, and the resistance providing structure is configured to enable the