Container set and sample preparation method using same

A method for preparing a sample for analysis from a specimen, comprising the steps, in order, of:

• fixing a specific substance in the specimen to a solid surface;
• removing impurities that are not fixed to the solid surface by centrifugal filtration;
• releasing away a substance to be collected from the specific substance fixed to the solid surface to a liquid;
• and
• collecting the substance to be collected that is released away in the liquid, wherein
• the centrifugal filtration and release of the substance to be collected into the liquid are performed using the same filter unit,
• the filter unit includes:
• a housing having two ends in which a sample introducing opening that may be closable is made at one of the two ends and a liquid discharging opening is made at another end;
• and a filter fixed to the housing,
• the sample introducing opening is configured such that solids and liquids can be therethrough introduced into a sample holding space surrounded by the housing and the filter,
• the liquid discharging opening is configured such that a filtrate transmitted through the filter can be therethrough discharged,
• after the centrifugal filtration, the filter unit and a closing unit are joined to each other, so that the substance to be collected is released away into the liquid in a state that the liquid discharging opening is spatially closed,
• the housing of the filter unit has a first joining portion,
• the closing unit has a second joining portion that is configured to be joinable to the first joining portion,
• the first joining portion of the filter unit and the second joining portion of the closing unit are configured such that the two joining portions are joinable to each other to produce an airtight state to close the liquid discharging opening spatially by the closing unit, and
• the filter unit and the closing unit are further pushed to each other to shorten a distance between the filter and the closing unit while the state that the two joining portions are joined is maintained, so that a space between the closing unit and the filter is made into a positive pressure relative to a pressure in the sample holding space, and
• the substance to be collected is released away into the liquid in this positive pressure state.