Sample dilution method and immunoassay method

A sample dilution method, comprising steps of:

• moving a ferrying unit bearing a first reactor already containing a sample from an initial position to a first workstation;
• dispensing a diluent into the first reactor located at the first workstation;
• uniformly mixing the sample and the diluent in the first reactor so as to form a diluted sample;
• moving the ferrying unit bearing the first reactor containing the diluted sample to a second position, and dispensing the diluted sample in the first reactor located at the second position into at least two empty second reactors;
• moving the ferrying unit bearing the second reactors containing the diluted sample to the first workstation, and dispensing a reagent into the second reactors located at the first workstation;
• and
• uniformly mixing the diluted sample and the reagent in the second reactors,
• wherein a buffer unit is provided, the first reactor is placed on the buffer unit, and after dispensing the sample into the first reactor on the buffer unit, the first reactor containing the sample is transferred from the buffer unit to the ferrying unit at the initial position, the ferrying unit is configured to make linear reciprocation between the initial position, the first workstation position and the second position, and
• wherein the empty second reactors are placed on the buffer unit, and after the diluted sample is dispensed into the second reactors, the second reactors containing the diluted sample are transferred from the buffer unit to the ferrying unit at the initial position.