In clinical tests, there are a number of inspection items in which a biological sample is used as a test sample. Among them, in immunoassays, it is known that interfering substances exist, which influence on the immunological reactions of the target substances. The influence is one which influences on the accuracy of the measured values, and there are some reports thereon.
The most common method for confirming and reducing the influence by these interfering substances is the method in which the test sample is preliminarily diluted so as to decrease the concentrations of the interfering substances. However, with this method, since the concentration of the target substance is also decreased together with the concentrations of the interfering substances, it is difficult to employ this method when a substance having a low concentration in the sample is to be measured. Further, since the dilution operation is added, the time required for the measurement is prolonged, so that the quickness is reduced. On the other hand, if the interfering substance is known, a compound having a function to inhibit or suppress the interfering activity is added or a pretreatment such as warming is performed. However, these methods are effective only for known specific substances. It is thought that unknown substances may adversely affect the measurement depending on the measurement items.
Japanese Laid-open Patent Application (Kokai) No. 9-304384 discloses to use a conjugated diene polymer having sulfonic groups or salts thereof for avoiding false positive results. However, for promoting the accuracy of measurements, avoiding the interfering substances which may exist in all biological samples is needed rather than the substance causing false positive results contained in special samples.    Patent Literature 1: Japanese Laid-open Patent Application (Kokai) No. 9-304384